MANUAL OF BOTANY: 
 
 COMPRISING 
 
 VEGETABLE ANATOMY AND PHYSIOLOGY, 
 
 OK 
 
 THE STRUCTURE AND FUNCTIONS 
 OF PLANTS, 
 
 WITH REMARKS ON CLASSIFICATION. 
 
 BY 
 
 WILLIAM MACGLLLIVRAY, A.M, LL.D./ 
 
 r.,ATE PROFESSOR OF NATURAL HISTORY IN MARISCHAL COLLEGE, ABERDEEN; AUTHOK 
 OF MANUALS OF GEOLOGY, BRITISH BIRDS, &C., &C. 
 
 SECOND EDITION. 
 
 LONDON : 
 
 ADAM SCOTT, CHARTERHOUSE SQUARE. 
 1853.
 
 GLASGOW: 
 
 W. 0. BLACKIK AND CO , PRINTERS. 
 VILLA FIKLD.
 
 ADYEETISEMEiNT. 
 
 IT has appeared to the author of this Manual, that 
 although many excellent treatises on the Structure, 
 Functions, Distribution, and Classification of Plants, have 
 been published in this country, and have contributed to 
 extend among us the knowledge of those most interesting 
 subjects, none of them is precisely fitted for the purpose 
 of affording a concise and yet comprehensive view of the 
 vegetable kingdom, such as might be useful to persons 
 desirous of obtaining correct information at as little ex- 
 pense of time and labour as possible. The writings of 
 Dr. Withering, Sir James E. Smith, Sir William Jack- 
 son Hooker, Professor Henslow, Professor Lindley, Dr. 
 Greville, and other eminent botanists among ourselves, 
 and of the many illustrious cultivators of botanical science 
 in France, Germany, Switzerland, and North America, 
 afford abundant materials for a treatise of the kind re- 
 quired. A practical acquaintance with the subject derived 
 from continued observation, experience obtained by teach- 
 ing it for several years, and an enthusiastic devotion to 
 the study of natural history in general, together with a 
 taste for methodical arrangement, might enable one to 
 select the most important facts, and to present them in 
 a perspicuous point of view, so as to supply the student 
 with a useful Introduction to the study of Botany. The 
 present treatise contains a condensed account of the 
 
 2091 21 8
 
 IV ADVERTISEMENT. 
 
 Structure and Functions of Plants, or of Vegetable Ana- 
 tomy, Organography, and Physiology, together with the 
 modifications of form and texture presented by the organs, 
 and the terms by which they are distinguished. As the 
 last are of especial importance with reference to the 
 Classification and Description of Plants, subjects to be 
 treated of in another volume, they have been repeated 
 and explained in an Alphabetical Glossary at the end of 
 the treatise. The works which have afforded the author 
 the most important aid are those of Linnseus, De Candolle, 
 Mirbel, Dutrochet, Richard, Smith, Lindley, and Henslow. 
 To these are to be added the excellent Manual of M. 
 Delafosse, and Dr. Thomson's Organic Chemistry. The 
 Illustrations used, with the exception of the woodcuts, 
 are those of Smith's Introduction to Botany. The 
 arrangement adopted, which in some parts is similar to 
 that of Professor Henslow, the author can state, from 
 experience in teaching, to be well adapted for communi- 
 cating a knowledge of the subjects treated of. 
 
 The great success of the Manual of Geology, and the 
 favourable reports respecting it which have emanated 
 from many individuals, some of them of the highest rank 
 as geologists, induce the author of the present volume 
 to hope that it may prove equally acceptable, and not 
 less useful.
 
 INTRODUCTION. 
 
 I. BOTANY is the Science which treats of Plants. It 
 is not confined to the Arrangement and Description of 
 these bodies, but embraces all that relates to their Struc- 
 ture, Functions, and Distribution. The name of this 
 science is derived from a Greek word, /Soranj, signifying 
 grass or herbage. As natural bodies are disposed into 
 three great classes, Minerals, Vegetables, and Animals, 
 and as the study of the first of these is named Mine- 
 ralogy, while that of the last is named Zoology, both 
 Greek compounds signifying the Doctrine of Minerals 
 and the Doctrine of Animals, so the Doctrine or Study 
 of Plants ought to be named BOTANOLOGY, or PHYTO- 
 LOGY, these terms being composed of Xoyoe, logos, doc- 
 trine, or discourse, and f3orarrj, above explained, or (j>vroi>, 
 phyton, a plant or vegetable. 
 
 II. Natural bodies or objects may be primarily dis- 
 posed into two vast series. Some are formed by the 
 aggregation of elementary particles or molecules, deter- 
 mined by the general laws of physics, and, although often 
 symmetrical, are not composed of parts or organs adapted 
 for the performance of functions having reference to the 
 growth, propagation, or preservation of the individuals. 
 Such bodies are therefore named INORGANIC. Others 
 are composed of parts or organs, mutually subservient, 
 and are named ORGANIC BODIES. They are possessed of 
 life, whereas the former are destitute of that property. 
 They all originate from a minute body, gradually enlarge 
 by receiving into their interior particles from without, 
 reproduce bodies similar to themselves, gradually decrease
 
 VI INTRODUCTION. 
 
 in vigour, and at length die. These organized bodies are 
 separated into two classes, ANIMALS and PLANTS, the 
 systematic or connected study of all that relates to which 
 constitutes the sciences of Zoology and of Botany. 
 
 III. In examining animals or vegetables, with the view 
 of acquiring a correct knowledge of them, it is not suffi- 
 cient to take note of their external appearance, inspect 
 their organs in a superficial manner, watch the changes 
 which gradually take place in them, or observe their 
 motions and habits. These changes and actions result 
 from their internal structure, and, before we can under- 
 stand them aright, we must make ourselves acquainted 
 with that structure. Two sciences, or branches of 
 science, take cognizance of the mechanism and functions 
 of the organs of animals and plants. That which has 
 reference to the form, structure, and disposition of the 
 organs, is named ANATOMY ; while to PHYSIOLOGY belong 
 their functions, or the offices which they perform. We 
 have thus, in Zoology, the distinct, but connected branches 
 of ZOOLOGICAL ANATOMY or ZOOTOMY, and ANIMAL 
 PHYSIOLOGY ; and in Botany the corresponding depart- 
 ments of VEGETABLE ANATOMY or PHYTOTOMY, and VEGE- 
 TABLE PHYSIOLOGY. These sciences, when applied to 
 the entire series of animals, or to that of plants, with 
 the view of discovering their similitudes, discrepancies, 
 and relations, of disclosing the modifications of their 
 various organs, the laws which determine the mutual 
 relations of these organs, and the connection between the 
 form, habits, and external circumstances of the objects 
 examined, assume the names of COMPARATIVE ANATOMY 
 and PHYSIOLOGY. 
 
 IV. Now, in treating of Plants generally, we shall 
 have, in the first place, to examine their various organs, 
 both externally and internally, and then to discover their 
 functions. These objects being very numerous, and
 
 INTRODUCTION. Vll 
 
 highly diversified in form and colour, it is necessary to 
 arrange them into groups, to describe the species, and 
 assign them distinctive characters and names. Each of 
 these three great divisions of Botany, namely, VEGE- 
 TABLE ANATOMY or ORGANOGRAPHY, as it is also called, 
 VEGETABLE PHYSIOLOGY, and the CLASSIFICATION OF 
 PLANTS, is composed of several subordinate sections, 
 which it is not necessary here to specify, as the multi- 
 plicity of terms used in Botany is apt to bewilder the 
 beginner, who can only, by a slow and gradual progress, 
 render himself familiar with them. From what has been 
 stated in this paragraph, it will appear that by Botany 
 is here meant the Science which examines the structure 
 and form of plants, determines their functions, and 
 describes, distinguishes, names, and arranges them. 
 The distribution of plants over the globe, their uses in 
 the economy of nature, their application to purposes 
 especially subservient to the welfare of the human spe- 
 cies, and other circumstances usually enumerated in 
 definitions, may all be referred to the above, although in 
 teaching the elements of the science, it may be expedient 
 to treat of them separately. 
 
 V. The study of Botany recommends itself in various 
 ways. It may, to some extent, be engaged in by indi- 
 viduals of either sex, and of almost every profession. 
 While Zoology, by the destruction of life, the disgust at 
 first excited by dissection, the difficulty of procuring 
 objects, and the necessity of extended journeys and 
 inurement to fatigue, is, in some of its departments at 
 least, repulsive to females ; Botany, by the beauty of its 
 objects, the facility with which they may be procured, and 
 the agreeable images and associations which they call 
 up in the mind, seems peculiarly adapted for them. 
 Although a simple study, when pursued merely so far as 
 to learn the names of plants, it is capable of calling into
 
 Vlll INTRODUCTION. 
 
 action the higher faculties of the intellect. Indeed, 
 natural history in general, if we judge of the difficulty of 
 a subject by the want of success of those who strive to 
 master it, seems to be a far more intellectual pursuit than 
 is generally imagined. How many warriors, statesmen, 
 poets, and novelists, have distinguished themselves by 
 the successful exercise of their talents, compared with 
 the very small number of really eminent naturalists ? 
 Greece produced but one great naturalist, Rome none, 
 and modern Europe, for a hundred warriors, can scarcely 
 show half a dozen of philosophic zoologists or botanists. 
 Yet, strange as it may seem, every individual is in some 
 respect a naturalist, and plants and animals excite the 
 curiosity even of infants. Would that the study of 
 botany, in particular, were made a subject of elementary 
 instruction ; for then the young would find in it an 
 inducement to forego much of the vicious practices in 
 which, through mere idleness, they are prone to engage. 
 No pursuit can be more conducive to health, or, unless 
 indulged in to excess, to mental serenity. But although 
 a familiarity with nature may seem necessarily to render 
 religious sentiments habitual, experience shows us, that 
 piety and proficiency in natural history do not always go 
 together. Still, he who is truly pious will find in the 
 study of botany much to gratify his feelings ; and he who 
 is not, may meet with much to excite his admiration of 
 the skill and contrivance displayed in the structure and 
 distribution of plants.
 
 TABLE OF CONTENTS. 
 
 INTRODUCTION. 
 
 MO* 
 
 Definition of Botany. Its various Branches, . v 
 
 SECTION I. 
 
 STRUCTURE OF 1'LANTS. 
 
 CHAPTER I. General Idea of Plants. Distinction between Animals 
 and Vegetables. Their principal characters and analogies, 
 
 CHAPTER II. Elementary Parts or Organs of Plants. General ac- 
 count of the Organs of plants : their internal structure. Mem- 
 brane and Fibre, Cellular Tissue, Woody Tissue, Vascular Tissue, 
 Spiral Vessels, and Ducts, Vacuities in the Tissue, and Receptacles 
 of peculiar Juices, 
 
 CHAPTER III. General Integument of Plants, and parts connected 
 with it. Structure of the Epidermis, Stomata, Hairs, Prickles, 
 Scales, and Glands, 
 
 CHAPTER IV. Compound Organs of Plants. Elementary, Rudi- 
 mentary, and Perfected Organs. General idea of Classification as 
 founded on the structure of plants. Characters of Dicotyledons, 
 Monocotyledons, and Acotyledons, 18 
 
 CHAPTER V. Form and Structure of the Root. Its structure, posi- 
 tion, duration, and texture. Fibrous, Tapering, Tuberiferous, 
 Lobiferous, Bnlbiferous, and Granuliferous Roots. Varieties of 
 form and direction, 23 
 
 CHAPTER VI. Form and Structure of the Stem. Its nature and 
 modifications. The Cormus, Tuber, Creeping Stem, Rootstock 
 or Rhizoma, Herbaceous Stem, Trunk, Stipe, Culm, Runner, and 
 Sucker. Consistence, Division, Direction, Form, Clothing, Sur- 
 face, and Pubescence. Internal structure of the Stem in Dicotyle- 
 b
 
 X CONTENTS. 
 
 FAGS 
 
 donous Plants; Epidermis, Herbaceous Envelope, Bark, Liber, 
 Woody Layers, Pith, Medullary Sheath, and Medullary Rays. 
 Structure in Monocotyledonous Plants. Structure of the root 
 compared with that of the stem, 29 
 
 CHAPTE R VII. Buds. Their nature, composition, and arrangement. 
 Development of branches. Subterranean buds : Turio, and Bulbs. 
 Bulbils, 45 
 
 CHAPTER VIII. Form, Structure, and Relations of the Leaves. Ge- 
 neral idea of the Leaves : their disposition and direction. The 
 Petiole, its insertion and form. The Limb. Division and nerva- 
 tion of Leaves : Curvinerved, Angulinerved. Simple Leaves, their 
 figure, with reference to their outline, base, sides, tip, and margins. 
 Expansion and consistence. Compound Leaves : palmiuerved, 
 pinninerved. Decompound Leaves. Surface, colour, and duration. 
 Appendages of Leaves : Tendrils, Spines, Pitcher. Vernation, . 49 
 
 CHAPTER IX. Inflorescence or mode of Flowering. The Peduncle, 
 its position and Relations. The Bractea : its modifications. In- 
 volucre, Cupula, Spatha. Bractea in grasses. The Inflorescence : 
 Whorl, Spike, Raceme, Capitulum, Corymb, Catkin, Spadix, An- 
 thodium, Sertule, Umbel, Panicle, Thyrsus, Cyme, and Fascicle, . 66 
 
 CHAPTER X. Organs of Reproduction considered generally. The 
 Flower, its receptacle. Flower-buds; estivation. Parts of the 
 Flower : sepals, petals, stamens, pistils, 79 
 
 CHAPTER XI. The Calyx. Its nature and composition. Monose- 
 palous and Polysepalous Calyx. Pappus, 85 
 
 CHAPTER XII. The Corolla. Its nature and situation. Monope- 
 talous Corolla; regular and irregular. Polypetalous ; regular and 
 irregular. Position of the Petals, duration and colours, . . 89 
 
 CHAPTER XIII. The Stamens. Their nature, number, proportion, 
 position, and direction. Filament, Anther, and Connective. Di- 
 rection, form, dehiscence, and cohesion of anthers. The Pollen, 
 its structure, development, and dispersion. Insertion of the 
 Stamens, 96 
 
 CHAPTER XIV. The Pistil. Its parts. The Ovary, its form, rela- 
 tions, and divisions. The Ovules. The Style and Stigma, . 103 
 
 CHAPTER XV. The Receptacle, Disk, and Nectary, . . . 110 
 
 CHAPTER XVI. The Fruit. The Pericarp, its composition and de- 
 hiscence. Varieties of Fruit. Simple Fruits : Follicle, Legume, 
 Nucula, Drupe. Aggregated Fruits : Etaerio, Cynorrhodon. 
 Compound Fruits : Caryopsis, Achenium, Carcerule, Samara,
 
 CONTENTS. XI 
 
 PAOB 
 
 Siliqua, Capsule, Acorn, Gourd, Berry, Apple, Hesperidium. 
 Collective Fruits : Fig aud Cone , . 116 
 
 CHAPTER XVII. The Seed. The Testa and Kernel. The Radicle, 
 Plumule, and Cotyledons. Dicotyledonous and Monocotyledonous 
 embryo, 126 
 
 CHAPTER XVIII. Structure of Flowerless Plauts. General obser- 
 vations. Structure of Ferns, Equisetacese, Marsileaceae, Lyco- 
 podiacese, Mosses, Hepaticae, Lichens, Characese, Algae, Fungi. 
 Acrogenous and centrifugal modes of growth, . . . 132 
 
 SECTION II. 
 
 FUNCTIONS OF PLANTS. 
 
 CHAPTER XIX. Germination, growth, and maturation of Plants. 
 Condition and progress of germination in Dicotyledonous and 
 Monocotyledonous Plants. Growth of Acotyledons, and of Plants 
 in general, . 139 
 
 CHAPTER XX. Vegetable Life, properties of organs, and stimulants 
 to vegetation. Properties of vegetable tissue, irritability, sleep 
 of plants, movements caused by touch, spontaneous movements, 
 Endosmose, action of poisons, stimulants to vegetation, action of 
 light, electricity and heat, air, and water, 147 
 
 CHAPTER XXI. Function of Nutrition. Absorption, its causes and 
 stimulants. The lymph or sap ; its progression ; channels of sap, 
 and causes of ascent. Transpiration. Respiration. Colour of 
 Plants. Effects of Respiration on the atmosphere, . . . 156 
 
 CHAPTER XXII. Nutrition continued. Elaborated or descending 
 sap, its descent. Local movements. Vegetable Secretions : Gum, 
 sugar, fecula, lignin : Fixed oils, wax, volatile oils, camphor, resins, 
 balsams, caoutchouc, acids, alkalies. Adventitious substances in 
 Plants : Lime, silica, soda. Excretions. Taste and colour. As- 
 similation. Pruning, grafting. Theories of the growth of Dico- 
 tyledonous stems. 'Continuance of growth, .... 169 
 
 CHAPTER XXIII. Function of Reproduction. Propagation by sub- 
 division. Reproduction by seeds. Floration, its stimulants and 
 periodicity. Horary expansion of flowers. Functions of the pe- 
 rianth. Fecundation: sexes; formation, protection, dispersion, 
 and action of pollen. Maturation of fruit. Development of ovules. 
 Progress of the seed. Growth of the fruit ; its action on the air, 
 and chemical changes in its substance. Dissemination. Preser- 
 vation of seeds and fruits. Growth and reproduction of flowerless 
 plants, 187
 
 Xll CONTENTS. 
 
 PAGK 
 
 CHAPTER XXIV Direction of the organs of Plants. Effect of 
 gravitation and light, ' . . .210 
 
 CHAPTER XXV. Metamorphosis of Organs. Eegular or theoretical 
 Metamorphosis, as exhibited by the leaves, stipules, bracteae, calyx, 
 corolla, stamens, and carpels. Irregular Metamorphosis of roots, 
 tu bers, the stem, leaves, flowers, and fruit, . . . .215 
 
 CHAPTER XXVI. Geographical Distribution of Plants. Stations 
 and Habitations. Circumstances facilitating or preventing migra- 
 tion. Influence of soil, moisture, and heat, .... 221 
 
 CHAPTER XXVII. Species, Varieties, and Hybrids, . . . 228 
 
 CHAPTER XXVIII. Diseases, Duration, Decay, and Decomposition 
 of Plants. Longevity of trees. Fall of the leaf. Vegetable life 
 and death. Decomposition. Fermentation : vinous, acetous. 
 Putrefaction. Vegetable soil, 233 
 
 CHAPTER XXIX. Linnsean system, 243 
 
 CHAPTER XXX. Natural system, 259 
 
 GLOSSARY, containing the terms applied to the modifications of 
 internal structure, and those of the external parts, . . . 267 
 
 INDEX, 269 
 
 DESCRIPTION OF THE FRONTISPIECE, PLATE I. Fig. 1. Structure 
 of wood, after Mirbel : a, hexagonal cells ; b, c, d, tubes of woody 
 tissue ; d, d, larger tubes of porous or pitted tissue ; e, e, spiral 
 vessels. Fig. 2. Embryo of Pinus Cembra, and as seen in a section 
 of the seed, also separate, and magnified. Fig. 3. Seedling plant 
 of Araucaria, the Norfolk Island Pine, with its four cotyledons, 
 and leafy branches. Fig. 4. A garden Bean, Faba vulyaris, laid 
 open, to show its two cotyledons, the radicle,/, and the caulicle or 
 plumule, rj ; also a bean germinating, in which are seen the split 
 testa or covering of the seed, the axis, or radicle and caulicle, with 
 the gemmule of rudimentary leaves.
 
 SECTION I. 
 
 STRUCTURE OF PLANTS. 
 
 CHAPTER I. 
 GENERAL CHARACTERS OF PLANTS. 
 
 NATURE OF PLANTS CONSIDERED GENERALLY. DISTINCTION 
 BETWEEN PLANTS AND ANIMALS. APPARENT MOTILITT OF 
 PLANTS NOT DEPENDENT UPON SENSIBILITY. ANALOGIES 
 OF PLANTS AND ANIMALS. DIVISIONS. 
 
 1. General Idea of Plants. A Plant or Vegetable may 
 be defined an organized living body, destitute of sensi- 
 bility and voluntary motion. Such a definition, however, 
 although a better cannot be given, affords no precise idea 
 of the nature of a plant. Such is the diversity among 
 the vegetable productions of the globe, as to form, sta- 
 ture, texture, colour, and other qualities, that the defini- 
 tion applicable to all, excludes the more obvious properties 
 of any of them. An oak, at first sight, seems to bear*' 
 no resemblance to a mushroom ; a palm-tree and a lichen 
 are, in many respects, very dissimilar ; a blade of sea- 
 weed and a stalk of wheat have little in common. Yet 
 not only are these all plants, but every organized body 
 not belonging to the animal kingdom, whether it shoot 
 up to the height of a hundred feet, or more, or scarcely 
 raise itself a twelfth of an inch from the surface of the 
 earth or rock, whether its texture be hard, like that of 
 the oak, or soft as jelly, whether it be divided into 
 numberless branches, clothed with thousands of leaves,
 
 2 DISTINCTION BETWEEN PLANTS AND ANIMALS. 
 
 and adorned with many beautiful and fragrant flowers, 
 or in the total absence of such organs, present not even 
 a determinate form, is a vegetable, and must not be 
 overlooked in attempting to form a general definition. 
 There is not a single organ that presents itself in every 
 plant: one has no root, another no stem, a third no 
 leaves, a fourth no flowers. To increase our perplexity, 
 some plants seem so nearly allied to some animals, that 
 we can hardly say where the series of vegetables ends, 
 and that of animals commences. 
 
 2. Essential Distinction between Plants and Animals. 
 Animals being possessed of sensibility and the power 
 of motion, are enabled to search for and select the sub- 
 stances capable of affording them nourishment ; and hav- 
 ing introduced them into their alimentary cavity, convert 
 them into a substance containing the elements of their 
 various organs. Their food consists of all kinds of ani- 
 mal and vegetable substances, for the assimilation of 
 which the digestive organs are greatly modified in the 
 different species. But plants, being always fixed in a 
 particular spot, and thus incapacitated from searching for 
 food, are nourished by the substances which surround 
 them, and imbibe or absorb, by their external surface, 
 the atmospheric air, water, and matters dissolved in them. 
 Having thus little choice, their organs of nutrition pre- 
 sent little diversity. As the parts of the animal body 
 cannot preserve a fixed position, while those of the vege- 
 table undergo no perceptible displacement, the motion of 
 the nutritious fluids must, in the former, depend upon 
 internal impulses, while, in the latter, it is excited by 
 causes acting from without, and unconnected with the or- 
 ganization, such as heat, evaporation, and moisture. Al- 
 though animals and vegetables are formed of the same 
 chemical elements, namely, oxygen, hydrogen, carbon, 
 and nitrogen, the last of these substances prevails hi ani-
 
 ANALOGIES OF PLANTS AND ANIMALS. 3 
 
 mals, while carbon is the principal constituent of plants. 
 Lastly, the organs of sensation and motion being nerves 
 and muscles, vegetables are necessarily destitute of these 
 elementary organs. Consequently, they have no heart, 
 or central organ of circulation, no vessels resembling 
 arteries, veins, lacteals, or lymphatics. 
 
 3. Apparent Motility in some Plants. Although, in 
 most cases, it is very obvious that plants have no sensa- 
 tion or voluntary motion, yet there are some which seem 
 to form an exception. Thus, the branches and leaves 
 of all plants direct themselves toward the light. Cer- 
 tain plants, at the approach of night, or in gloomy wea- 
 ther, close their leaves and flowers ; and there are some, 
 as the Sensitive Plant, that shrink, as it were, on being 
 touched. An American marsh-plant, Venus's Fly-trap, 
 has its leaves terminated by an appendage of two lobes, 
 furnished with long spines on the edges, and in the centre 
 of this appendage a space which secretes a fluid attrac- 
 tive to flies. Should an insect alight on this space, the 
 lobes instantly close, and the animal, pressed against the 
 sharp points on the secreting disk, is soon put to death. 
 The plant named Sun-dew has its leaves bordered with 
 hairs, the tips of which are often seen covered with a 
 drop of clear clammy fluid, and which, on being irritated, 
 immediately fall down. If the lower part of the stamens 
 of the common Barberry be touched, they will spring 
 against the pistil or central organ of the flower. But 
 these phenomena differ from the voluntary motion of 
 animals, and are explained on mechanical principles. 
 
 4. Analogies of Plants and Animals. But although 
 plants differ in many respects from animals, they agree 
 in others. Thus both are produced from a germ or egg, 
 increased by the assimilation of foreign matter, attain 
 their full development, propagate their species, decline, 
 lose their vitality, and, being reduced to the condition of
 
 4 RECAPITULATION. 
 
 inorganic matter, become subject to the decomposing in- 
 fluence of the atmospheric agents, and are ultimately dis- 
 persed, so that their elementary particles are free to enter 
 into new combinations. Plants, as well as animals, re- 
 spire air, and have a continual motion of their fluids, 
 which are partly converted into solid matter, and partly 
 dispersed by passing through the pores of the superficial 
 parts. They are equally composed of solids and fluids ; 
 and the former are disposed in the forms of membranes, 
 cellules, and tubes. These analogies, however, are far 
 from being close, and the organs of plants are not, with- 
 out great latitude, comparable to those of animals. Op- 
 portunities of pointing out affinities will occur, when we 
 treat of the structure and functions of the different parts 
 of vegetables. 
 
 5. Divisions of the Subject. The study of Botany ad- 
 mits of a fourfold division: 1. Structural Botany com- 
 prises the laws of vegetable structure, or organography ; 
 this is internal or external, and it is independent of the 
 presence of a living principle. 2. Physiological Botany 
 relates to the living functions of plants, and their modifi- 
 cations in conditions of health and of disease. 3. De- 
 scriptive Botany embraces the description and nomencla- 
 ture of plants. 4. Systematic Botany is devoted to the 
 principles by which plants are associated with, or dis- 
 tinguished from, one another. 
 
 RECAPITULATION. 
 
 1. Define a Plant. Does a general definition afford a pre- 
 cise idea of the nature of plants ? Why does it not ? Are 
 some plants extremely unlike others ? Are there many 
 organs common to all plants ? 2. What difference is there 
 in the mode of nutrition of plants and animals ? Why should 
 the motion of the fluids depend on internal agents in animals, 
 and on external in plants ? What differences exist in respect
 
 ELEMENTARY PARTS OF PLANTS. 5 
 
 to chemical composition ? Have plants nerves and muscles ? 
 Are they destitute of a heart and vessels analogous to arteries 
 and veins? 3. Mention some examples of apparent motion 
 in plants. Upon what does it depend ? 4. What are some 
 of the analogies between plants and animals? 5. What 
 divisions of the subject are usually adopted ? 
 
 CHAPTER II. 
 ELEMENTABY PARTS OF PLANTS. 
 
 GENERAL ACCOUNT OF THE ORGANS OF PLANTS. THEIR IN- 
 TERNAL STRUCTURE. CELLULAR AND VASCULAR TISSUE, 
 WITH THEIR MODIFICATIONS. 
 
 6. Organs of Plants. The parts of which a plant is 
 composed are named its Organs. Thus, the root, the 
 stem, the leaves, the petals, are organs, that is, parts dis- 
 tinguishable from each other by position, form, structure, 
 and function. These organs are composed of Elementary 
 parts, differing from one another, but so minute as gene- 
 rally to be distinctly visible only with the aid of the mi- 
 croscope. These minute parts are named Elementary 
 Organs, Organic Tissue, or Vegetable Tissue. The organs 
 of plants, properly so called, or those visible externally, 
 and forming conspicuous and readily distinguishable parts 
 of plants, are physiologically divided into two kinds ; 
 namely, the nutritive or conservative organs, or those sub- 
 servient to the development and preservation of the in- 
 dividual ; and the reproductive organs, or those which 
 have reference to the continuation of the species. 
 
 7. Nutritive or Conservative Organs. The Root, the 
 Stem, the Branches, the Leaves, and some other parts, 
 are those by which the function of nutrition is performed.
 
 b INTERNAL STRUCTURE OF PLANTS. 
 
 It is by means of them that the plant imbibes air and 
 moisture, circulates its juices, subjects them to the action 
 of the air, converts them into solid matter, and throws 
 off the superfluous or useless parts. In very many plants, 
 these organs may be arranged into two series, the as- 
 cending, and the descending, although the distinction is not 
 of much use. The root and its parts, having a tendency 
 to shoot downwards into the earth, belong to the former ; 
 while the stem, which shoots upwards, the leaves, flowers, 
 and other parts, are referred to the latter. 
 
 8. Reproductive Organs. The various parts forming the 
 Flower and the Fruit, constitute the organs destined for 
 the continuation of the species. The flower includes 
 various parts an outer envelope, named the Calyx ; an 
 inner envelope, named the Corolla ; certain bodies named 
 the Stamens, and a central body named the Pistil. This 
 last, when fully developed, constitutes the Fruit, which 
 is divisible into several parts. These organs are at pre- 
 sent merely alluded to, introductorily to the subject, for 
 the examination of their structure must be preceded by 
 that of the elementary tissue of which they are composed. 
 
 9. Internal Structure. The minute particles of matter 
 of which plants are composed, are combined or united in 
 such a manner as to form two modifications of structure. 
 If we take any common plant, and cut its stem across, 
 we perceive that it is composed of a spongy or cellular 
 mass, denser in some parts, and presenting larger aper- 
 tures in others. If we cut the same stem longitudinally, 
 we find the cells assume a different appearance, being 
 elongated, and in some parts like fibres or tubes. Apply- 
 ing the microscope to the transverse section, (Fig. 1, a), 
 we find its cellules arranged like a network, in the midst 
 of which are the larger openings. In the longitudinal 
 section, (Fig. 1, b), the network is seen to be formed of 
 more or less elongated cells, while the large apertures
 
 CELLULAR TISSUE. 7 
 
 seen in the transverse section are found to belon* to 
 
 O 
 
 cylindrical tubes. Different plants present different ap- 
 
 (Fig. 1 ) 
 
 pearances, and in some there are none of those cylindrical 
 fibres or tubes. But the conclusion to which we come 
 is, that plants in general are composed of angular cells 
 and cylindrical tubes, arranged so as to be more or less 
 elongated in the direction of the axis of the stem or other 
 organs. If we examine the cells and tubes more minutely, 
 we find them to be formed of two kinds or modifications 
 of the elementary matter, namely, membrane and fibre. 
 
 10. Membrane and Fibre. The walls of the internal 
 minute cavities, whether short or elongated, are composed 
 of membrane, which is extremely thin, colourless, trans- 
 parent, and generally tears equally in every direction. 
 It is destitute of visible pores or perforations, although, 
 from the passage of liquids through it, we cannot but 
 suppose that apertures of some kind exist in it. Fibre, 
 as here considered, does not constitute the elongated cells 
 or fibres of plants, but is an extremely attenuated form 
 of the elementary substance, which is sometimes straight, 
 but usually spiral, or tortuous. Many observers allege 
 that it is hollow, while others consider it as solid. Of 
 these two elementary textures, Membrane and Fibre, all 
 the organs of plants are composed. The forms under 
 which they exhibit themselves are: Cellular Tissue and 
 Vascular Tissue. 
 
 11. Cellular Tissue. The general appearance of the 
 Cellular Tissue may be compared to that of froth obtained 
 by blowing bubbles in soap-water; but the cellules or
 
 8 CELLULAR TISSUE. 
 
 vesicles, of which it is composed, assume many forms. 
 The pith of plants is entirely composed of it, hut it also 
 enters largely into the structure of the other parts, and 
 in many is the only tissue. It is always transparent and 
 colourless, for, although it presents a vast diversity of 
 colours, and, in fact, is the seat of colour in all parts of 
 plants, this is owing to the colouring matter of various 
 kinds which it contains. This colouring matter is fre- 
 quently fluid, hut often composed of granules adhering to 
 the walls of the cells or immersed in liquid. The most 
 common appearance of the cellular tissue is that of a mul- 
 titude of spheroidal cellules, rendered more or less angu- 
 lar by being compressed. Frequently in the transverse 
 section of a plant, (Fig. 2, a), they present an irregularly 
 
 (Kg. 2.) 
 
 VV />=r^ X y/^Y Jv ^i^-> \\ >-// 1 
 
 hexagonal form, resembling that, of honeycomb. In the 
 longitudinal section, b, each cell exhibits, more or less 
 perfectly, the form presented by the vertical section of 
 the geometrical solid called the dodecahedron. Their 
 walls are destitute of visible pores, but generally allow a 
 transfusion of fluid from one cell to another. Although 
 always very small, the cellules vary exceedingly in dimen- 
 sions, the largest being iu diameter about the 20th part 
 of an inch, the smallest not more than the lOOOdth. They 
 often leave vacuities between them, which are named Inter- 
 cellular Passages. 
 
 12. Varieties of Cellular Tissue. Two kinds of Cellu- 
 lar Tissue may be distinguished ; the Common, and the 
 Ligneous, the latter being of a denser texture, and com- 
 posed of more elongated cells. Another division is into
 
 CELLULAR TISSUE. 
 
 Membranous and Fibrous. The Membranous Cellular 
 Tissue, or tbat in which the walls of the cellules are com- 
 posed solely of membrane, is the more common kind, and 
 may be considered as the basis of the vegetable struc- 
 ture, it being never wanting in plants, while many are 
 entirely composed of it. The cellules of this variety may 
 be globular, (Fig. 3, a) ; oblong, b ; cubical, c ; muri- 
 
 (Fig. 3.) 
 
 2T 
 
 form, or resembling the bricks in a wall, d ; prismatic, e ; 
 elongated, f\ fusiform or spindle-shaped and dotted, g \ 
 or irregular, h. The Fibrous Cellular Tissue is of two 
 kinds, being composed either of membrane and fibre com- 
 bined, or of fibre alone. Of both kinds there are several 
 modifications, but it will suffice here to mention a few of 
 those of the former. Sometimes an oblong cell has a 
 fibre spirally twisted round it, (Fig. 4, a) ; or the fibre 
 
 (Fig. 4.) 
 
 may anastomose irregularly, b ; or the cell may have a 
 reticulated appearance, produced as it were by two fibres 
 crossing each other, c ; or the fibres may be longitudinal 
 and parallel, d. 
 
 13. Woody Cellular Tissue. This is also named Woody 
 Fibre, it having at one time been supposed to consist of 
 fibres infinitely divisible. It is, however, merely a modifi- 
 cation of cellular tissue, in which the cells are much
 
 10 
 
 VASCULAR TISSUE. 
 
 elongated, generally pointed at both ends, and although 
 lying close together in bundles, having no direct com- 
 munication with each other. This kind of tissue is pos- 
 sessed of great tenacity, and is chiefly that employed in 
 the manufacture of thread and cords, the fibres of flax, 
 hemp, and phormium being composed of it. In the woody 
 parts of plants three varieties have been observed. In 
 one, (Fig. 5, a), the walls are even ; in another, b, they 
 
 (Fig. 5.) 
 
 present, adhering to them, scattered granules ; and in 
 the third, c, the walls have regular series of circular 
 glandules, having an opaque centre. This last kind is 
 peculiar to the trees named Coniferse, such as the Firs, 
 Pines, and Junipers. 
 
 1 4. Vascular Tissue. The vessels of plants have little 
 resemblance to the blood-vessels of animals, which are 
 branched and anastomose, or unite with each other. 
 Vegetable Vascular Tissue, on the contrary, is composed 
 of very elongated membranous tubes, tapering at each 
 end, and having a spiral fibre within them, or having 
 their walls marked with broken spiral lines, or dots ar- 
 ranged in a circular or spiral direction, (Fig. 6, a, b, c, d). 
 The vessels of plants, in fact, might be considered merely 
 as modifications of the common cellular tissue. They 
 are represented by some as having a communicating aper- 
 ture at their junction b, while others find no pore or per- 
 foration in them. Two principal kinds of vessels are dis-
 
 DUCTS. 
 
 11 
 
 tinguished, namely, Spiral Vessels, and Ducts, which, 
 however, show intermediate gradations. 
 
 ,~ 
 
 15. Spiral Vessels. A membranous tube, tapering to 
 a point at each end, and having within it a cylindrical 
 fibre spirally rolled, and capable of being untwisted, ia 
 the variety of elementary cellule to which the name of 
 spiral vessel is given, c, d. From a fancied resemblance 
 in form and function to the windpipe of an animal, it also 
 frequently obtains the name of Tradiea. Some have 
 considered this kind of vessel as formed of a fibre spirally 
 twisted, without any membrane, while others state that 
 it is composed of a fibre rolled round or within a cylin- 
 drical membrane. The fibre also has been variously 
 represented as cylindrical, flat, or tubular. A spiral 
 vessel may be formed of a single thread or fibre, c, or of 
 two or any number up to twenty, d. In the former case, 
 it is said to be simple, in the latter compound. These 
 vessels are extremely delicate, their diameter averaging the 
 lOOOdth of an inch. They are very seldom found in the 
 root, bark, or wood, but are frequently abundant in the 
 other parts. They are easily discovered on breaking 
 asunder the leaves and stalks of many plants, as of the 
 Strawberry, the Dogwood, <fcc., when they unroll, and 
 present themselves as delicate filaments like those of 
 spiders. 
 
 16. Ducts. All the varieties of vessels not furnished
 
 12 VACUITIES IN THE TISSUE. 
 
 with an elastic spiral filament are named Dads. The 
 fact of these vessels being merely elongated cellules is 
 manifested by the analogous ramification of the elemen- 
 tary fibre upon them, giving rise to various appearances ; 
 and the fact of their being only modifications of the spiral 
 vessels is shown by some vessels being true tracheae in 
 one part, and ducts in another, where the spiral fibre has 
 been broken. The following are the principal varieties. 
 When the membranous tube presents at irregular inter- 
 vals, or in close contact, rings, which seem to be frag- 
 ments of a ruptured spiral thread, e, it is named an 
 Annular Duct. When the spiral fibre is in some parts 
 continuous, in others branched and anastomosing, and 
 sometimes presents the appearance of bars, (Fig 6,f), the 
 vessel is named a Reticulated Duct. The Dotted Duct, g, 
 is that in which the fibre has been broken into small and 
 nearly equal fragments. Ducts are generally much 
 larger than true spiral vessels, many of them being dis- 
 tinctly visible to the naked eye, and some so large as to 
 admit a hair. 
 
 PI. I., Fig. 1, is a highly magnified representation of 
 the tissue of plants, in a longitudinal section: a a a, be- 
 ing cellular texture ; b, continuous woody fibre ; c, dotted 
 woody fibre ; d d d, ducts of various kinds ; e e, spiral 
 vessels. 
 
 Besides these elementary organs, properly so called, 
 there are various cavities resulting from their mode of 
 connection or separation, which require notice. 
 
 17. Vacuities in the Tissue. As already mentioned, 
 the cellules often leave between them vacuities, to which 
 the name of Intercellular Passages is given, and which 
 always contain a fluid. They vary in size, being large 
 in succulent plants. Besides these passages, there are 
 often in plants vacuities or Lacunce in the tissue, which 
 are bounded by its cellules, and although usually of irre-
 
 RECAPITULATION. 13 
 
 gular form, are sometimes very uniform. They have no 
 lining membrane, but do not communicate with the in- 
 tercellular passages ; they contain air, on which account 
 they are appropriately named Air-cells. 
 
 18. Receptacles of Peculiar Juices. Sometimes the 
 intercellular passages are unusually dilated by the fluids 
 which they contain ; or, by the pressure of the latter, 
 cavities are formed in the cellular tissue. Such cavi- 
 ties, filled with the peculiar juices of the plant, are by 
 some named Proper Vessels, Receptacles of the Juice, 
 Reservoirs of the proper or peculiar fluids, or Accidental 
 Reservoirs. Although destitute of lining membrane, 
 their walls are generally compact, being formed of con- 
 densed cellules. They vary in size and form ; and, al- 
 though often very regular, sometimes have no definite 
 figure or arrangement. 
 
 Remarks. Of these modifications of membrane and 
 fibre are formed all the parts of plants. The varied 
 combinations of the vascular and cellular tissues give rise 
 to an endless variety of structure and external form, and 
 produce an equal diversity in the properties of the juices 
 and secretions. Many plants are entirely composed of 
 cellules, but the greater number consist of both cellules 
 and vessels. These elementary parts form certain com- 
 pound organs, which will be described in the next chapter. 
 
 RECAPITULATION. 
 
 6. What is meant by the term Organ? Of what are 
 organs composed ? How are the organs divided ? 7. Give 
 an account of the Conservative Organs. 8. What are the 
 Reproductive Organs ? 9 How many kinds of Elementary 
 Structure are there ? What is observed in the transverse 
 and longitudinal sections of a common plant ? 10. What is 
 meant by Membrane ? In what respects is Fibre different ?
 
 14 GENERAL INTEGUMENT. 
 
 11. What does Cellular Tissue resemble? What are its 
 properties ? Describe its general appearance. Are its walls 
 pervious, or porous? 12. How many kinds of cellular tissue 
 are there ? Give an account of membranous cellular tissue. 
 Describe the fibrous variety. 13. Of what nature is woody 
 cellular tissue? How many varieties of it are usually 
 described ? How are they distinguished ? 11. Define 
 Vascular Tissue. What are its two principal kinds ? 15. 
 Give a general account of the Spiral Vessels. 16. In what 
 respects do ducts differ? Describe their three varieties. 
 
 17. What kinds of vacuities occur in the tissue of plants? 
 
 18. What is the nature of the receptacles of the peculiar 
 juices of plants? 
 
 CHAPTER III. 
 
 GENERAL INTEGUMENT OF PLANTS, AND PARTS 
 CONNECTED WITH IT. 
 
 19. Epidermis. The tissue, or intimate structure, 
 of all plants is composed of the elementary parts de- 
 scribed in the preceding chapter; hut there are parts 
 more or less complex, which may also be considered as 
 elementary. These are the Cuticle or general envelope 
 of plants, and the various organs immediately connected 
 with it. 
 
 The Epidermis or Cuticle is the delicate membrane 
 which invests almost all the organs of plants. It has 
 been so named on account of its analogy, as to position at 
 least, with the Cuticle or Scarf-skin of animals. Plants, 
 however, have not a true cutis or skin, and their cuticle 
 is in many respects different from that of animals. The 
 Epidermis presents the appearance of a transparent pel- 
 licle, but, when examined with the microscope, it is found
 
 STOMATA AND HAIRS. 15 
 
 to be composed of three distinct parts. The outermost 
 layer is an extremely delicate film, homogeneous in its 
 structure, and perforated by minute oblong pores. Under 
 it is a layer of flattened cellules, sometimes arranged in 
 two or three series. The other element of the cuticle 
 consists of the organs named stomata. 
 
 20. Stomata. A stoma is an aperture in the cu- 
 ticle, laterally bounded by two generally curved vesicles, 
 
 . 7.) 
 
 (Fig. 7, a, b). Some observers, however, deny the existence 
 of any opening in the stomata, which they consider as 
 cutaneous glands. But the general opinion is that they 
 are pores, which are capable of being closed by the en- 
 largement or elongation of the two cellules forming their 
 sides. They vary in form, being sometimes square, 
 sometimes oblong or circular. It is commonly supposed 
 that they are subservient to transpiration, and are con- 
 nected with the reticulated tubes lying in or under the 
 epidermis. In many tribes of flowerless plants, and in 
 the parts of aquatic plants that are under Avater, they are 
 not found. 
 
 21. Hairs. On the cuticle are observed various pro- 
 longations resembling hairs or bristles, which are com- 
 posed of cellules, generally elongated, and disposed in a 
 single series. Sometimes these hairs are composed each 
 of a single cellule, (Fig. 8, a) ; more frequently of several 
 cellules, b ; in which case they have the appearance of 
 a tube divided by transverse partitions. They may be 
 branched, c, or covered with small processes, which are 
 themselves also sometimes branched, d, or they may be
 
 16 
 
 PRICKLES. 
 
 divided in a stellular manner, e. Hairs are generally 
 acute, a, b, but often they end obtusely, or are enlarged 
 
 (Fig. 8.) 
 
 at the extremity, /, and secrete a viscid fluid. In this 
 case they are usually called glandular hairs. A tapering 
 pointed hair having a central canal, and situated on a 
 glandular prominence, is called a sting, g, as in the 
 Nettle ; such hairs are analogous to the poison-fangs of 
 serpents. Considered in a general sense, hairs constitute 
 what is called the Pubescence, of which various kinds are 
 described. Thus the surface of a plant is said to be 
 downy, when the hairs are short, delicate, and flexuous ; 
 viUoue, when long, straight, and soft ; pilose, when long, 
 scattered, and rather soft ; hirsute, when rather long and 
 stiff; tomentose, when longish, soft, entangled, and 
 pressed close to the surface ; silky, when long, very 
 slender, closely pressed, and glistening ; ciliated, when 
 arranged along the margin of an organ, like cilia or eye- 
 lashes ; bearded, when long and tufty ; bristly, when coni- 
 cal, short, and stiff; hispid, when conical, long, and 
 f'ff. Hairs are not found on true roots, nor on any part 
 the stem placed underground, nor on parts immersed 
 in water. They may occur on any other part of the sur- 
 face of a plant, however, as well as in its cavities. 
 
 22. Pricldes. These organs may be considered as 
 complex rigid hairs, (Fig. 9, a). They are of a conical 
 form, straight or curved, and are composed of cellular 
 tissue. Being attached only to the bark, they are easily
 
 SCALES AND GLAND3. 
 
 distinguished from spines, which are abortive branches, 
 or prolongations of the woody tissue. Prickles, Aculei, 
 
 (Fig. 9 ) 
 
 occur on all parts of plants, excepting the organs called 
 stamens, but are rarely found elsewhere than on the 
 stem. 
 
 23. Scales. Thin, flat, membranous, scurf-like pro- 
 cesses formed of cellular tissue, are named Scales, and 
 differ from hairs chiefly in being more compound, and not 
 of a cylindrical or tapering form, (Fig. 9, &). This kind 
 of scale is also named Lepis, and is to be distinguished 
 from another, which is a kind of rudimentary leaf, or 
 squama. Ramenta, (Fig. 9, c), are thin, brownish scales, 
 composed entirely of cellular tissue, and distinguished 
 from leaves by the absence of buds in their axillae. Of 
 this kind are the scales so abundant on the stalks, and 
 leaves of Ferns. 
 
 24. Glands. By the term Gland, or Glandida, is de- 
 signated a small, more or less dense, prominence in the 
 tissue immediately beneath the cuticle, which it causes 
 to project, (Fig. 9, d). Warts, or Verruca}, are roundish 
 glandules, filled with opaque matter, which, when nume- 
 rous, give the surface a kind of roughness designated Vy 
 the term scabrous. Glands may be sessile, or stalked. In 
 the former case, they present the appearance of round- 
 ish, conical, or cylindrical bodies ; in the latter, they are 
 roundish bodies, secreting some peculiar fluid, and ele- 
 vated upon a stalk.
 
 18 COMPOUND ORGANS OF PLANTS. 
 
 RECAPITULATION. 
 
 19. What is the nature of the Epidermis or Cuticle ? Of 
 how many parts is it composed ? 20, Describe the Stoma. 
 Is it of general occurrence ? 21. What is meant by a Hair ? 
 What are the principal varieties of hairs? What is the 
 Pubescence? Mention some of the kinds of surface produced 
 by varieties of pubescence. 22. What are Prickles ? 23. 
 Define Scales. What other organs have been so named? 
 24. What are Glands ? 
 
 CHAPTER IV. 
 COMPOUND ORGANS OF PLANTS. 
 
 GENERAL VIEW OF THE ARRANGEMENT OF PLANTS FOUNDED 
 UPON THEIR STRUCTURE. 
 
 25. Organs of Plants. The Elementary Organs, the 
 nature of which is disclosed by minute examination, with 
 the aid of the Microscope, combine in various manners 
 to form the parts of plants to which \ve give the name of 
 Compound Organs, or simply of Organs, and which have 
 already been mentioned as divisible into two kinds, Organs 
 of Nutrition, and Organs of Reproduction. These organs 
 do not all exist in every species of plant, nor in any spe- 
 cies do they shew themselves all at once, but are succes- 
 sively developed, and sometimes are transformed into 
 one another. To obtain a general idea of them, it will 
 therefore be expedient to follow the progress of growth 
 in a common plant, from the period at which the seed 
 begins to germinate, to that at which it produces a seed 
 like itself.
 
 RUDIMENTARY AND PERFECTED ORGANS. 19 
 
 26. Rudimentary Organs. In every seed is contained 
 within the general envelopes a small organized body, 
 which is named the Embryo, PI. I., Fig. 4, f, g. When 
 germination has commenced, this body swells, bursts the 
 envelopes, and shoots out into two parts, one of which 
 proceeds downwards into the ground, while the other 
 ascends into the air. The descending part, f, which is 
 named the Radicle, ultimately becomes the Root. The 
 ascending part, g, the Plumule or Caulide, is the rudi- 
 ment of the Stem, leaves, and flowers. The point of 
 junction of the plumule and radicle, is the Neck or Life- 
 knot, and from it proceed laterally one or more append- 
 ages, which are named Cotyledons or Seminal Leaves, 
 PI. II., Fig. 7, they being in fact parts which become 
 the first leaves of the plant. In this stage those parts 
 may be called rudimentary organs. 
 
 27. Perfected Organs. When the Root, PI. II., Fig. 7, 
 has attained its full growth, it usually presents a fleshy 
 body, variously branched, and furnished with Fibrils or 
 Radicles, having at their extremity a small spongy body, 
 by which nourishment is extracted from the soil. The 
 plumule, on becoming developed, shoots up into a Stem, 
 which subdivides into branches and twigs. The organs 
 connected with it are at first contained in Buds. The 
 Leaves are flattened expanded organs of a green colour, 
 which absorb nutritious fluids from the atmosphere, and 
 give out such as have become noxious or superfluous. After 
 them appear the Flowers, which are complex organs con- 
 taining the rudiments of new seeds in an inert state, and 
 the parts necessary for fecundating them. When the semi- 
 nal germs have been vivified, the flower withers, with the 
 exception of the part containing the seeds, which con- 
 tinues to grow, and constitutes the Fruit. Thus, the essen- 
 tial or fundamental organs of plants may be reduced to 
 five, of which three, the Root, the Stem, and the Leaves,
 
 20 
 
 CHARACTERS OF DICOTYLEDONS. 
 
 being subservient to the growth and preservation of the 
 individual, are named Organs of Nutrition ; while the 
 remaining two, the Flower and the Fruit, being subser- 
 vient to the continuation of the species, are the Organs 
 of Reproduction. These organs come now to be exa- 
 mined in succession ; but preparatorily to their inspec- 
 tion, it becomes expedient to enter into a short exposi- 
 tion of some circumstances, which must frequently be 
 alluded to in the course of our descriptions. 
 
 28. General Idea of Classification. All the individual 
 plants that correspond with each other in all their parts, 
 and have been derived from one common stock, constitute 
 species. Species agreeing closely together in their more 
 important features, form genera. The genera are vari- 
 ously grouped into tribes, families, and orders; but all 
 these groups ultimately arrange themselves into three 
 comprehensive groups, named Dicotyledons, Monocotyle- 
 dons, and Acotyledons. 
 
 29. Characters of Dicotyledons. The seeds of this 
 great class of plants are composed of two fleshy bodies, 
 named Cotyledons, (Fig. 10, 1), a a, and the Embryo, 
 
 b c, or essential rudiment of the future plant, already de- 
 scribed. It is the circumstance of there being two cotyle- 
 dons that gives the name to the group. The stem also 
 presents peculiarities, by which it may be easily distin- 
 guished, (Fig. 10, 2). When young, it has in the centre
 
 CHARACTERS OF MONOCOTYLEDONS. 21 
 
 a cylindrical mass of cellular tissue, named the Pith. This 
 is surrounded by a layer of vascular tissue, named the 
 Medullary Sheath. The external part or envelope is the 
 Epidermis. Between the medullary sheath and the epi- 
 dermis is formed a mass of vascular and cellular tissue, 
 which at length separates into two parts, the inner form- 
 ing a layer of Wood, the outer a layer of Bark. At the 
 end of the second year, between the wood and the bark is 
 found a new double layer of wood and bark. In the third 
 year, there are three layers of wood, and three layers of 
 bark ; and in this manner the stem increases in thick- 
 ness, year after year. In a transverse section of such a 
 stem there are seen the central pith, several concentric 
 rings of wood, an equal number of thinner and usually 
 confused layers of bark, together with bauds of cellular 
 tissue radiating from the pith to the hark, and named 
 Medullary Rays. The existence of two cotyledons in 
 the seed, of successive layers of wood and bark, and of 
 medullary rays, characterize this class of plants, which 
 are also named Exogenous, from the circumstance of 
 their stems enlarging by the apposition of new layers of 
 wood externally to those already formed. 
 
 30. Character of Monocotyledons. In this class, the 
 seed, (Fig. 10, 3), is chiefly composed of a mass of albu- 
 minous matter, a, inclosing the embryo, b, which, in ger- 
 minating, pushes upward, and ultimately perforates the 
 single conical cotyledon. In the stem, (Fig. 10, 4), there 
 is no distinction of parts into pith, wood, and bark, it 
 being a cylindrical mass of cellular tissue, in which are 
 dispersed bundles of vessels. The addition of new mat- 
 ter is made towards the centre, and the outer parts are 
 harder than the inner. In consequence of this peculia- 
 rity in the mode of growth of the stem, these plants are 
 also called Endogenous. 
 
 31. Characters of Acotyledons. The plants of which
 
 22 RECAPITULATION. 
 
 this great class is composed are destitute of seeds, pro- 
 perly so called, and consequently have no cotyledons ; 
 whence their name. From their not having spiral ves- 
 sels in their structure, they being formed either of cellu- 
 lar tissue alone, or of cellular tissue and ducts, they are 
 also named Cettulares. Their reproductive organs, which 
 are termed Sporules, are minute granular bodies, having 
 no distinct parts, but germinating by the increase of cel- 
 lular tissue. This class is divided into several orders ; 
 Ferns, Equisetaceac, Lycopodiaceee, Mosses, Hepaticse, 
 Lichens, Fungi, and Algae, 
 
 The Acotyledons being destitute of flowers, are also 
 named Flowerless or Cryptogamous Plants; while the 
 Monocotyledons and Dicotyledons, being furnished with 
 these organs, are named Phanerogamous or Phcenoga- 
 mous. Botany, in fact, is encumbered with superfluous 
 terms. 
 
 These preliminary explanations being made, we may 
 now proceed to examine the five principal organs, with 
 their modifications and appendages. 
 
 RECAPITULATION. 
 
 25. Of what are the Organs of plants composed? 26. 
 Mention the parts observed in a germinating Seed. 27. What 
 are the five principal organs of a perfect plant ? 28. Into 
 what three classes may all plants be arranged ? 29. Describe 
 the seed of a Dicotyledonous plant. What parts are ob- 
 served in its stem ? What appearance is presented by a 
 transverse section of it? 30. In what respects do the 
 Monocotyledons differ ? 31. What are the general cha- 
 racters of the Acotyledons ? What is meant by Exogenous 
 and Endogenous ; by Phanerogamous and Cryptogamous ?
 
 STRUCTURE OP THE ROOT. 23 
 
 CHAPTER V. 
 FORM AND STRUCTURE OF THE ROOT. 
 
 32. General Idea of tlie Root. The organs of nutri- 
 tion, or those subservient to the growth and preservation 
 of the individual, are the Root, the Stem, and the Leaves. 
 Those intended for the continuation of the species are 
 the Flower and the Fruit. Many authors divide a plant 
 into two parts, the Descending Body, and the Ascend- 
 ing Body, the former composed of the Root, the latter 
 of the other organs. The ROOT, PI. II., Fig. 7, may 
 he defined that part which terminates the plant be- 
 low, and penetrates into the soil. It thus fixes the 
 plant in a commodious situation, and extracts nutritious 
 matter from the earth for its support. It generally con- 
 sists of two parts, the Caudex or body, and the Radicles or 
 fibres. Its upper part, from which spring the stem and 
 the leaves, being frequently narrowed, is named the Neck. 
 The radicles are the only essential parts of the root, it 
 being by their usually spongy extremities that moisture 
 is absorbed. Many botanists have considered as roots 
 all those parts of a plant which are immersed in the 
 soil ; but, in so doing, they have sometimes confounded 
 the stem with the root. Thus, what they call a creep- 
 ing root, PI. II., Fig. 6, as in Mint, is merely a subter- 
 ranean part of the stem. Although the root is usually 
 fixed in the ground, there are plants which, floating on 
 the water, send out radicles which never reach the bot- 
 tom ; and in tropical countries there are flowering plants 
 which grow upon trees, into the bark of which their roots 
 are inserted. 
 
 33. Structure of the Root. A root of the ordinary 
 kind, in Dicotyledonous plants, consists of cellular and
 
 24 POSITION OF THE ROOT. 
 
 vascular tissue, but without spiral vessels, and, like the 
 stem, is divisible into a central part, in which, however, 
 are no pith or concentric circles, although there are 
 radiating plates of cellular tissue, named medullary 
 rays ; and a cortical part, analogous to the bark. This 
 arrangement may be seen in the Carrot, of which the 
 outer red portion is the bark. The cuticle, or epider- 
 mis, differs from that of the skin in having no stomata. 
 The lower part generally divides into branches, these 
 into subordinate divisions, terminated by small bodies, 
 composed of cellular tissue, without epidermis, and named 
 Spongioles. It is remarkable that the root never has a 
 green colour, unless after being for some time exposed to 
 the air. 
 
 34. Position of the Root. Although the root usually 
 terminates the plant below, the stem and branches may, 
 by the application of moisture, and by being kept in the 
 shade, be made to give off roots. As an example of this 
 may be adduced the celebrated Banyan tree of India, 
 the horizontal branches of which send down roots, which, 
 fixing themselves in the ground, are ultimately converted 
 into stems, and, continuing to enlarge, form gigantic 
 props. The rooting of the Mangrove is very peculiar : 
 it consists, not, as in ordinary trees, of subterranean, 
 but of aerial divisions of the stem, forming numerous 
 arches, and thus affording a large base by which the 
 tree secures a firm hold in the loose and swampy soil in 
 which it grows. Captain Basil Hall describes a forest of 
 Mangroves, which had so encroached, by their remark- 
 able mode of rooting, upon the sea, that pioneers in boats 
 were obliged to clear a way for the traveller to proceed. 
 
 35. Duration and Texture. Some plants continuing 
 only for a single year, or a single season, have annual 
 roots. Other plants require two years for their full de- 
 velopment, and thus have biennial roots. Perennial, or
 
 FIBROUS ROOT. 25 
 
 lasting roots, are those of woody plants, or of soft plants 
 which die down to the ground annually, but shoot up, 
 year after year, their roots remaining alive. Annual and 
 biennial roots are generally of a soft and more or less 
 succulent texture, as are those of many perennial plants; 
 hut the roots of trees and shrubs are, like themselves, 
 hard and woody. 
 
 36. Principal kinds of Root. There is great diver- 
 sity in the form of the root ; but the principal modifi- 
 cations, or those more commonly observed, are the fol- 
 lowing : 
 
 The Fibrous Root. Radix fibrosa. PI. II. , Fig. 5. 
 This kind of root consists of a great number of fibres or 
 filaments, which are sometimes simple or unbranched, at 
 other times variously subdivided. The fibrous root is 
 that seen in monocotyledonous plants, and is commonly 
 considered as that of all annual plants. But in many of 
 these, although slender, it presents exactly the same 
 form and structure as the Tapering Root. The fibres of 
 the roots of most grasses that grow in dry sandy soil are 
 remarkably downy ; and those of grasses growing in 
 very moist situations are covered with similar prolonga- 
 tions, though much thicker. The protecting power of 
 these plants in fixing sand-banks is remarkable : the 
 sand-hills on the French coast, between Dunkirk and 
 
 DESCRIPTION or PLA.TE II. Fig. 5. Fibrous Root of a 
 grass. Fig. 6. Creeping Root-stem of Mint. Fig. 7. Fusi- 
 form or Tapering Root of a Radish, with the two cotyledons, 
 and young leaves. Fig. 8. Abrupt Root of Scabiosa succisa. 
 Fig. 9. Tuber. Fig. 10. Oval Lobes of an Orchis. Fig. 
 11. Palmate Lobes of an Orchis. Fig. 12. Digitate Lobes of 
 an Orchis. Fig. 13. Cormus of Crocus. Fig. 14. Tunicate 
 Bulb of Allium. Fig. 15. Scaly Bulb of Lilium. Fig. 16. 
 Granulated Root of Saxifraga granulata.
 
 20 TUBERIFEROUS ROOT. 
 
 Boulogne, especially about Calais, are covered with 
 mat-grasses, which keep them firm, and the banks on 
 our Flintshire shores, in the parish of Llanissa, are simi- 
 larly fortified. In what is called the Creeping Root, 
 PI. II., Fig. 6, the fibres alone are the roots. 
 
 37. The Tapering Root. Radix fusif or mis. PL II., 
 Fig. 7. This root, named also conical and perpendicu- 
 lar, or vertical, is generally fleshy, and of an elongated 
 conical form, either simple, that is, undivided, or branched 
 at its lower extremity. The most common example is 
 afforded by the garden Carrot. In the Radish it is 
 spindle-shaped, or tapering toward both ends. When 
 slender and much branched, as in trees and shrubs, as 
 well as in many herbaceous plants, it is usually con- 
 founded with the fibrous root, which, however, is peculiar 
 to monocotyledonous plants. By tracing through their 
 gradations the numberless varieties of the cultivated 
 Turnip, it will be seen that its "bulbs" are merely modi- 
 fications of the conical root. Another remarkable va- 
 riety is that to which the name of Radix prcemorsa, 
 Abrupt Root, has been given, PI. II., Fig. 8. This 
 is, in fact, a tapering root, of which the lower or de- 
 scending part has decayed, so that it seems as if bitten 
 off. A common example of it is seen in Scabiosa suc- 
 cisa, the Devils-bit Scabious, respecting which the old 
 opinion, as expressed by Gerarde, was as follows : " The 
 great part of the root seemeth to be bitten away : old 
 fantastick charmers report, that the divel did bite it for 
 envie, because it is an herbe that hath so many good 
 vertues, and is so beneficial to mankinde." 
 
 38. The Tuberiferous Root. Radix tuberifera. PI. II. 
 Fig. 9. Although most roots may be considered as 
 modifications of the Fibrous and the Tapering, many 
 present remarkable appendages, and require to be sepa- 
 rately considered. Thus, the Tuberiferous Root is a
 
 GRANULIFEROUS ROOT. 27 
 
 fibrous root, to which are attached fleshy or amylaceous 
 knobs or tubers, which, being furnished with buds, are 
 considered as a kind of subterranean stems, and will be 
 afterwards spoken of. A familiar example is the Potato. 
 If the term Tuber be appropriated to the potato, and 
 similar subterranean productions furnished with buds, 
 it becomes necessary to apply another to those fleshy 
 bodies, which are merely reservoirs of nutritious matter. 
 Professor Liudley proposes naming them pseudo-tubers, 
 or false or spurious tubers ; but as they are neither 
 tubers, nor yet in any respect spurious, I think they may 
 rather be named Lobes. 
 
 39. The Lobiferous Root. Radix lobifera. PI. II., 
 Figs. 10, 11, 12. A fibrous root, having attached to it, 
 or connected with it, one or more masses, or lobes, of 
 cellular tissue, charged with amylaceous matter, and in- 
 tended as reservoirs for the future development of the 
 plant, is termed lobiferous. Lobes of this kind are seen 
 in Orchideous plants, and are of various forms. Thus, 
 they are oblong or ovate in Orchis mascula, (Fig. 10); pal- 
 mate, or shaped like a hand, as in Orchis latifolia, (Fig. 
 11); digitate, or finger-like, as in Satyrium albidum, (Fig. 
 12). They are extremely numerous and irregularly 
 branched in Corallorrhiza. 
 
 40. The Bidbiferous Root . Radix bidbifera. PI. II., 
 Figs. 14, 15. This is a fibrous root, surmounted by a 
 fleshy body named the Disk, which supports a Buttt, or 
 peculiar kind of bud, to be afterwards described. It is 
 only from vague.ly considering all subterranean parts as 
 roots, that the bulb, lobe, and tuber, have been mistaken 
 for roots. PI. II., Fig. 14, Tunicate Bulk of AUium; 
 (Fig. 15), Scaly Bulb of Lilium. 
 
 41. The Granuliferous Root. Radix granulifera. 
 PI. II., Fig. 16. When a great many small lobes, 
 having an eye or bud, and consisting of fleshy scales,
 
 28 RECAPITULATION. 
 
 grow in clusters, and are scattered on the fibres of the 
 root, the latter is said to be granulated, as in a very 
 common plant, Saxifraga granulata. 
 
 42. The Fasciculate Root consists of a fasciculus, or 
 bundle of slender fleshy bodies, issuing from the neck of 
 the plant, as in Dahlia. 
 
 43. Direction of the Eoot. The root may be vertical, 
 as in the Carrot and Parsnip ; oblique ; or horizontal. 
 Frequently all these directions may be found in the same 
 root. The extent to which roots spread depends chiefly 
 on the nature of the soil : but in large trees, the roots 
 being frequently unable to penetrate deeply into the hard 
 subsoil, assume a great lateral extension, their extremities 
 often passing far beyond those of the branches. Other 
 circumstances relating to this subject will be mentioned 
 in treating of the physiology of the root. It may be 
 here remarked, that in many plants, belonging to the 
 Acotyledonous series, the root does not exist as a dis- 
 tinct organ. 
 
 RECAPITULATION. 
 
 32. What are the organs of Nutrition ? and of Repro- 
 duction ? Define the Hoot. What are its parts ? Is the 
 root always fixed in the ground ? 33. What is the structure 
 of the root in dicotyledonous plants ? Is it often green ? 
 
 34. Does the root always proceed from the base of the stem ? 
 
 35. How are roots named with reference to their duration ? 
 
 36. Enumerate the principal varieties of the root. Describe 
 the Fibrous Root. 37. What is a tapering or conical root ? 
 What changes of form does it present ? What is a praemorse 
 or abrupt root ? 38. Why are some roots named tuberife- 
 rous? What is a tuber? 39. In what respect does a lobe 
 differ from a tuber? 40. Describe the bulbiferous root? 
 41. What is meant by granuliferous ? 42. What is the 
 fasciculate root? 43. What are the three principal direc- 
 tions of the root ?
 
 STRUCTURE OF THE STEM. 29 
 
 CHAPTER VI. 
 FORM AND STRUCTURE OF THE STEM. 
 
 44. General Idea of the Stem. The Stem may be 
 defined that part of a plant, which, proceeding from the 
 root, either extends under ground, or ascends into the 
 air, and supports the leaves and flowers. Although all 
 Phanerogamous plants are furnished with a stem, this is 
 sometimes so short as to seem to he wanting, the leaves 
 and flower-stalks appearing to spring from the top of the 
 root. When this is the case, the plant is said to be 
 stemless, acaulis. There are some kinds of flower-stalks, 
 namely, the Scape and the Radical Peduncle, which, being 
 conspicuous, are liable to be confounded with the stem, 
 properly so called. On the other hand, there are stems, 
 such as the Rhiwma and Tuber, 47, 49, which, being 
 subterranean, have been mistaken for roots. These 
 parts will presently be explained. In the meantime, let 
 it be understood that the organ here considered as the 
 stem is the ascending caudex of the plant, or that part 
 to which the leaves, when there are any, are attached. 
 
 45. Different lands of Stem. The direction, form, 
 texture, consistency, and clothing of stems, produce an 
 almost endless variety in this organ, of which the prin- 
 cipal kinds, however, may be reduced to eight. Of these, 
 four are subterranean : the Cormus, Tuber, Rhizoma, 
 and Creeping Stem; and four aerial : the Stem, Trunk, 
 Stipe, and Culm. 
 
 46. The Cormus. The Cormus, PI. II., Fig. 13, is 
 the enlarged base of the stem of certain monocotyledo- 
 nous plants, forming the reproductive portion of such as 
 are destitute of an aerial stem. It is developed under 
 ground, and is of a roundish or oblong form. By many
 
 30 SUBTERRANEAN STEMS. 
 
 botanists it has been described as a kind of root, or con- 
 sidered as a solid bulb. It consists of cellular tissue, 
 with bundles of vessels and woody fibre. Examples are 
 seen in the Crocus, Colchicum, and Arum. 
 
 47. T/ie Tuber. This kind of subterranean stem, often 
 considered as a modification of the root, PI. II., Fig. 9, 
 may be defined an oblong or roundish body, of annual 
 duration, composed chiefly of cellular tissue, with a great 
 quantity of amylaceous matter, intended for the develop- 
 ment of the stems or branches which are to spring from 
 it, and of which the rudiments, in the form of buds, are 
 irregularly distributed over its surface. The Tuber is 
 thus not a root, but a kind of stem. Examples are seen 
 in the Potato and Arrow-root. Nearly allied to it is 
 the organ named the Lobe or Pseudo-tuber, in which 
 there is only a single bud, f 38. 
 
 48. The Creeping Stem. This kind of stem, Soboles, is 
 that which many botanists have named the Creeping Moot, 
 PI. II., Fig. 6. It is a subterranean stem, of a slender, 
 elongated form, running nearly horizontally, emitting 
 roots at intervals, and sending up shoots or new plants. 
 The best examples of it are seen among the Grasses and 
 Carices ; for example, the Couch-Grass, Triticum repens, 
 Elymus arenarius, Triticum junceum, and Carex arenaria, 
 have stems of this kind, which, extending to a great 
 length, and sending up shoots, while their radical fibres 
 are numerous, and plentifully furnished with fibrils, serve 
 to bind down the loose sand on the sea-shore, 36. 
 
 49. The Rootstock. The Ehizoma or Rootstock is a 
 fleshy stem, varying in form, running horizontally under 
 the surface, or partially protruded from it, and sending 
 forth new stems at its anterior or upper extremity, while 
 the other extremity gradually decays. Such a stem is 
 easily distinguished from the root, by its increasing at 
 the part nearest the leaves, and not by its lower end, by
 
 STEM, TRUNK, STIPE. 31 
 
 its presenting traces of the leaves of preceding years, and 
 by the appearance of buds upon it. A familiar example 
 is seen in the Iris. 
 
 50. The Stem. Although this is a general term for 
 the ascending caudex, it is applied peculiarly to that 
 kind of aerial stem, Caulis, which is of a soft or herba- 
 ceous nature, as distinguished from such as are hard or 
 woody. It may be positively defined the ascending part 
 of the plant which bears the leaves and flowers, and ne- 
 gatively that kind which is not a Cormus, Tuber, Creep- 
 ing Stem, Rootstock, Trunk, Stipe, or Culm. It may 
 vary in its direction from erect to prostrate; in form, 
 from round to angular; in being simple or branched; in 
 having its surface smooth or hairy; and in other circum- 
 stances. 
 
 51. The Trunk. The Trunk, Truncus, is the woody 
 stem of trees and shrubs, such as the Oak, Ash, and 
 Hawthorn; and it is peculiar to dicotyledonous plants. It 
 may be described as of an elongated conical form, its 
 diameter being greatest at the base, and gradually be- 
 coming less towards the top. At its lower part, it is to 
 a variable extent destitute of divisions, but towards its 
 upper extremity it sends out brandies, which divide into 
 twigs. Internally, it is composed of concentric layers, 
 varying in number, and disposed around its axis; and it 
 increases in diameter by the annual addition of a woody 
 layer, and a thinner layer of bark, at the part near the 
 surface, where the wood and the bark are in contact. 
 (Fig. 10, 2). 
 
 52. The Stipe. The Stipe, Stipes, is the kind of 
 woody stem peculiar to Monocotyledonous trees, and a 
 few others. When destitute of branches, as it generally 
 is, it presents the appearance of a slender column, being 
 little thicker at the base than toward the top, frequently 
 larger in the middle than elsewhere, and crowned by a
 
 32 CONSISTENCE OF STEMS. 
 
 tuft of leaves and flowers. Internally, it has no appear- 
 ance of concentric layers, and presents no distinction of 
 wood and bark. It increases in thickness by the addi- 
 tion of fibres to its interior, and elongates by the deve- 
 lopment of the bud at its summit : of this kind are the 
 stems of Palms. (Fig. 10, 4). 
 
 53. The Culm. The Culm or Straw, Culmus, is the 
 kind of stem peculiar to grasses, and plants nearly allied 
 to them. It is generally simple or unbranched, fistulous, 
 or having an internal cavity, and marked at intervals 
 with joints or knots, formed by transverse partitions. 
 The leaves are alternate, and at their base invest the 
 stem with a kind of sheath. The culm, however, may 
 be branched, or solid, or destitute of knots; so that a 
 general character, including all its varieties, is not easily 
 given; and many botanists have thought the distinction 
 superfluous. 
 
 ' 54. Other varieties of Stem. Among the more re- 
 markable kinds of stem not already enumerated, are the 
 Runner and the Sucker. The former, Sarmentum, is a 
 very slender prostrate stem or shoot, PI. III., Fig. 22, 
 at its extremity producing roots and a young plant, 
 which, in like manner, sends out new runners. The 
 most familiar example is that of the Strawberry. The 
 Sucker, Surcidus, is a branch which, proceeding from 
 the neck of the root under ground, becomes erect on 
 emerging, and produces leaves, flowers, and branches ; 
 as in many Roses. But it is unnecessary to specify all 
 the varieties presented by the stem, and still less to give 
 a name to each. 
 
 55. Consistence of Stems. Plants are popularly dis- 
 tinguished, with reference to the consistence of their 
 stems, into herbs, shrubs, and trees. 1. Herbs, or herba- 
 ceous plants have soft, green, animal stems, as chick-weed 
 and groundsel. 2. Shrubs, or suffruticose or semi-lig-
 
 n 
 
 BRANCHES. 33 
 
 eous plants, have stems of which the hase is hard and 
 endures for several years, while the extremities of the 
 branches are soft and die annually, as lilac, sage, and 
 thyme. 3. Trees have hard, woody, perennial stems, as 
 the trunk of dicotyledons, and the stipe of palms. 
 4. Stems are further distinguished as solid, or destitute 
 of internal cavity, as in the oak; hollow, or fistulous, as 
 in reeds; spongy, or composed internally of loose, elastic, 
 cellular tissue, as in typha; succulent, or juicy, when 
 composed of a denser form of cellular tissue, filled with 
 fluid, as in cactus. Various other terms are employed 
 by botanists, the meanings of which are obvious, as stiff", 
 flexile, brittle, <fec. 
 
 56. Branches. The divisions of the stem bear the 
 general name of branches, or rami. The direction of 
 young branches is generally upward ; but as they increase 
 in size, they assume more of a horizontal direction, from 
 the effect of gravity, or from their effort to seek the 
 light, when the upper branches have attained a certain 
 size. The angle of a branch varies in different trees, but 
 is pretty constant in each species, and affords marked 
 characters: there is the very acute-angled, or compressed 
 branch of the pyramidal poplar ; the divaricating 
 branches, which stand off at nearly right angles from 
 the stem, vis-a-vis to each other; the patent, or irregu- 
 larly spreading branches; and the pendulous branch of 
 the Fraxinus excelsior. The last must be distinguished 
 from the branch of the weeping willow, which becomes 
 pendulous from weakness: the forifier are originally 
 retroverted; the latter " weep" from the effect of gravity. 
 
 57. A stem destitute of branches is said to be simple, 
 as in white lily; alternately branched, when the branches 
 proceed alternately from the stem; distichous, or two- 
 ranked, when they spread in two opposite directions, as in 
 Silver Fir; four-ranked, or brachiate, when they spread in
 
 34 DIRECTION, ETC., OF THE STEM. 
 
 four directions, in pairs which cross one another alter- 
 nately, as in Lilac ; forked, bifurcating, or dichotomous, 
 when they occur in pairs which are regularly and re- 
 peatedly divided, with a flower-stalk springing from each 
 division, as in Chlora, PI. III., Fig. 17; determinately 
 branched, when each branch, before terminating in a 
 bud, sends off shoots in a circular form, as in Erica 
 tetralix, Azalea, PI. III., Fig. 23, <fec. ; mwh branched, 
 when repeatedly divided into branches, without any 
 definite order, as in the Apple and Gooseberry. 
 
 58. Direction, form, appendages, and surface of the 
 stem. 1. With respect to its direction or mode of 
 growth, the stem is erect or prostrate; creeping, when it 
 lies on the ground, and sends down roots, as in Lysima- 
 chia nummularia; trailing, in the Strawberry; dinging, in 
 the Ivy, PI. III., Fig. 20; climbing, in the Vine. 2. As 
 to its form, it is round or angular; two, three, or four, 
 or five-sided; knotted or nodose; jointed, geniculate, 
 <fcc. 3. The appendages of stems are usually leaves, 
 but these organs are sometimes wanting, and they are 
 replaced by large scales, as in Orobanche, PL III., Fig. 
 18; or the stem is winged, when it has flat leafy borders 
 running along its angles, and formed by prolongations of 
 leaves, PI. IV., Fig. 36. 4. The surface is variously 
 smooth or glabrous; mealy or farinaceous; glaucous, 
 when the powdery matter constitutes a very fine layer, 
 
 DESCRIPTION or ,PLATE III. Stems and Bads. Fig. 17. 
 Forked stem of Chlora perfoliata. Fig. 18. Scaly stem of 
 Orobanche. Fig. 19. Radicant stem of Ivy. Fig. 20. Twining 
 from left to right, in Lonicera. Fig. 21. Twining from right 
 to left, in Convolvulus. Fig. 22. Sarmentum, or Runner, of 
 Fragaria vesca. Fig. 23. Stem determinately branched, in 
 Azalea. Fig. 24. Three pairs of Buds, in Lonicera ccerulea. 
 Fig. 25. Bud of jEsculus Hippocastanum.
 
 INTERNAL STRUCTURE OF THE STEM. 35 
 
 of a sea-green colour, and is easily removed, as in Chlora 
 perfoliata; scabrous or rough; papillose, when covered 
 with small tubercles; warty, when it presents small, 
 roundish excrescences; dotted, spotted, streaked, grooved, 
 corky, <fcc., terms sufficiently suggestive of their mean- 
 ing. 5. By pubescence, is meant the down of plants, 
 consisting of soft, short hairs, which partially cover the 
 cuticle; it is described as downy, villous, pilose, hir- 
 sute, tomentose, silky, velvety, ciliated, and bristly. 
 These terms will be found in the glossary at the end of 
 the volume. 
 
 59. Thorns. Some twigs, being imperfectly developed, 
 lose their power of extension, assume a hard texture, 
 terminate in a sharp point, and are then named Thorns, 
 Cuspides. Sometimes they bear leaves, as in the Sloe 
 and Hawthorn. Some trees, as the Pear and Sloe, which 
 are naturally thorny, on being transplanted into a rich 
 soil, lose their thorns, which, by the abundance of 
 nourishment, are converted into leafy twigs. Thorns, 
 PI. IX., Fig. 120, must not be confounded with Prickles, 
 Fig. 121. The former are continuous with the woody 
 tissue of the plant, while the latter are merely attached 
 to the surface. Thorns, in fact, are modified branches, 
 while prickles are indurated -hairs. Nor are they to be 
 confounded with Spines, Spince, which, as will after- 
 wards be explained, are metamorphosed leaves. 
 
 We now proceed to examine the internal or anatomical 
 structure of the stem. 
 
 60. Internal Structure of the Stem. If we take the 
 stem of a herbaceous plant, such as the Field Scorpion- 
 grass, Myosotis arvensis; that of a grass, such as the 
 cultivated Wheat, Triticum hibernum; that of a common 
 tree, such as the Ash, Fraxinus excelsior; and that of a 
 Palm, such as Corypha umbraculifera ; we find, on 
 examining them, a diversity of structure, which shows
 
 36 STEM OF DICOTYLEDONOUS PLANTS. 
 
 that we cannot refer to a single type the modifications 
 which that organ presents. Although a general review 
 of the whole vegetable kingdom, with respect to this 
 subject, cannot be undertaken, it will suffice to afford a 
 general idea of it, that we examine the stem of a tree 
 belonging to the Dicotyledonous, and that of one taken 
 from the Monocotyledonous series. The distinctive 
 characters of these great series have already been briefly 
 given in \\ 29, 30. 
 
 61. Stem of Dicotyledonous Plants. A transverse 
 section (Fig. 10, 2, p. 20) of the trunk of any of our 
 common trees, an Ash, an Oak, or a Willow, presents 
 two distinct parts, one of which, occupying the interior 
 from the centre to near the circumference, is the Wood, 
 or Woody Body; while the other, the Bark, or Cortical 
 Body, is situated at the exterior, so as to envelope and 
 enclose the wood. Each of these parts, the Wood and 
 the Bark, is composed of two distinct portions, the one 
 fibrous or vascular, the other cellular or parenchy- 
 matous. Of the Woody Body, the cellular part occupies 
 the centre, where it forms a cylindrical column, which is 
 named the Pith or Internal Pith; while the fibrous part, 
 or Wood, is arranged in layers around the pith. In the 
 Bark, on the other hand, the cellular part is placed at 
 the exterior, where it forms a kind of parenchymatous 
 covering to the whole plant, and is named the Herba- 
 ceous Envelope, or Older Pith; while the fibrous part, or 
 the Bark, is placed internally. The Woody Body, and 
 the Cortical Body are thus two parts organized in an 
 inverse direction, and which also increase in an inverse 
 direction by annual layers, which are added to the ex- 
 terior of the wood, but to the interior of the bark. 
 
 62. Enumeration of the Parts observed. The preced- 
 ing explanation affording only a general idea of the parts 
 composing the stem of a tree, we may now examine
 
 THE EPIDERMIS. 37 
 
 them somewhat more closely. In the centre is the Pith 
 (Fig. 11, a, 1), a cylinder of cellular tissue, surrounded 
 
 Fig. 11.) 
 
 by the Medullary Sheath, 2, Proceeding outwards, we 
 count five Woody Layers, 3, 4, 5, 6, 7; of which some 
 of the inner, 3, 4, 5, are of a denser texture, and darker 
 colour, than the outer, 6, 7; the former being collectively 
 named the Duramen or Heart Wood, the latter the Al- 
 burnum or Soft Wood. In the Bark, in like manner, we 
 find five layers, 8, 9, not so easily distinguishable, of 
 which the inner 8, being softer, are named the Liber, or 
 Inner Bark; the outer, 9, or harder, the Cortex, or Outer 
 Bark. Externally to the latter is the Herbaceous En- 
 velope, 10, which is cellular, and of a green colour; and, 
 lastly, at the surface of the stem, the Epidermis or 
 Cuticle, 11. Proceeding from the pith or its sheath, and 
 traversing the woody layers, in the form of radii, as seen 
 in a transverse section of the stem, are numerous vertical 
 plates of a kind of cellular tissue, usually named Medul- 
 lary Rays. This name, however, being apt to deceive 
 the student, I shall call them, what they really are, 
 Medullary Plates, Similar medullary plates, but much 
 less conspicuous, are observed in the bark. Let us now 
 examine these parts in succession, beginning with the 
 outermost. 
 
 63. The Epidermis. The Epidermis or Cuticle, already 
 described, p. 14, as the general integument of plants, is 
 very apparent in young stems or twigs, from which it
 
 38 HERBACEOUS ENVELOPE. 
 
 may be easily separated. Since it is constantly distended 
 by the cortical layers, as the stem enlarges in diameter, 
 and has only a certain degree of extensibility, it is torn 
 and destroyed when the trunk has acquired a certain 
 size. This original epidermis must not be confounded 
 with that of old trunks, which is the outer layer of the 
 herbaceous envelope, hardened by contact with the air. 
 This latter kind of epidermis also tears and splits in pro- 
 portion as the trunk increases in thickness, sometimes 
 dividing longitudinally and sometimes transversely. 
 Sometimes it separates in plates, and is quickly re- 
 newed, as is seen in the White Birch, in which numerous 
 layers exist at the same time. The epidermis is often 
 coloured with the juices of the subjacent cellular tissue, 
 but when washed, it is transparent and of a grayish- 
 white. It is composed of one or several plates of cellules 
 covered by a delicate membrane, and when young, pre- 
 sents the minute apertures named Stomata, p. 15, which, 
 however, are only found on stems directly exposed to air 
 and light, for the epidermis of stems placed under ground 
 or in water, and that of roots are entirely destitute of 
 them. The surface of the epidermis is also furnished in 
 some dicotyledonous plants with small glands, named 
 Lenticels; and is generally or frequently covered with 
 hairs, 21. 
 
 64. The Herbaceous Envelope. When the epidermis 
 is peeled off, which it may easily be in many twigs, as in 
 the Elder, we find exposed a cellular tissue of a green 
 colour. The reason of its appearing green is because it 
 contains numerous small grains of that colour. It is 
 very succulent, especially in spring, but as it becomes 
 old, it assumes a white colour, like the central or inner 
 pith. It is this substance which, being very highly 
 developed, forms the cork of commerce. This substance 
 detaches itself naturally every eight or nine years, and it
 
 BARK OR CORTICAL LAYERS. 39 
 
 is usually separated artificially one or two years before 
 this period; for this purpose that season of the year is 
 chosen, when the inner bark adheres most closely to the 
 wood, for then the whole cellular envelope may be re- 
 moved, without fear of detaching the liber. If the herba- 
 ceous envelope be removed, it is reproduced. When 
 old, it splits and tears, like the epidermis, in consequence 
 of being distended by the pressure from within. This 
 part appears to be of great importance, as it is here that 
 the decomposition of the carbonic acid absorbed by the 
 plant takes place. 
 
 65. The Bark or Cortical Layers. On removing the 
 herbaceous tissue, we come to the Bark, which is gene- 
 rally formed of a number of layers corresponding to the 
 age of the tree. Every year there is formed a layer of 
 bark, which is produced on the inner surface of the pre- 
 viously formed layer, so that this part increases in thick- 
 ness by additions from within, while the wood increases 
 by layers added to its surface. The outermost layer of 
 the bark is thus the oldest. Some of those which are 
 most external, having become hard, are distinguished by 
 the name of the Outer Bark, or the Cortical Layers. 
 Each of them is composed of longitudinal fibres, which 
 are curved, or alternately separate and unite, so as to 
 produce a kind of network. This disposition is very re- 
 markable in some plants, and especially in the Lace-tree, 
 in which the cortical layers, on being separated and 
 stretched out, resemble lace, or linen of loose texture. 
 The layers are traversed by medullary rays, proceeding 
 from the herbaceous tissue, and penetrating in the form 
 of pyramids through their meshes. 
 
 66. The Liher or Inner Bark. The innermost part of 
 the bark, which is named the Liber, is composed of a 
 vascular network, of which the elongated meshes are 
 filled with cellular tissue. Its different laminae are also
 
 40 BARK ITS DIVISIONS. 
 
 separated by thin layers of cellular tissue. Like the 
 other parts of the bark, it is capable of being reproduced 
 when it has been removed; but in this case it must be 
 guarded against the contact of air. It is one of the most 
 essential organs of vegetation, and is the seat of the 
 cambium, or elaborated juice from which the different 
 parts are produced. The liber is hardened each year, 
 forming a layer of the bark, and by means of the cam- 
 bium new layers are formed at its inner surface. The 
 inner bark was named liber, from its being in some cases 
 made into paper, or from its layers being frequently 
 separable, like the leaves of a book. Paper was for- 
 merly made by the Egyptians from the papyrus anti- 
 quorum, a species of reed growing on the banks of the 
 Nile. The inner bark of the stem was separated by 
 means of a needle into thin plates or ribands, which 
 were united together until they formed the size required, 
 and were then pressed and dried in the sun. The plates 
 in the centre were considered the best; and each plate 
 diminished in value according as it receded from that 
 part. 
 
 67. The division of the bark into cortical, cellular, or 
 herbaceous envelope, and liber, orjibrous inner bark, has 
 not been found sufficiently precise to explain the struc- 
 tural peculiarities in all cases. By the best modern 
 writers, bark is described as composed of four distinct 
 parts: 
 
 (1). Epidermis, or the external and cellular envelope, 
 continuous with the epidermis of the leaves. This is 
 never renewed. The following parts increase by succes- 
 sive additions to their interior. 
 
 (2). Epiphlosum, or a cellular portion lying imme- 
 diately under the epidermis. Cork is the epiphlcerum of 
 Quercus suber. 
 
 (3). MesopMceum, or a cellular portion, lying imme-
 
 WOODY LAYERS. 41 
 
 diately under the epiphlceum. This portion differs from 
 the preceding in the direction of its cells. 
 
 (4). Endophlceum, or liber, a part of which is cellular, 
 and a part woody. 
 
 68. Tlie Woody Layers. Beneath the liber or inner- 
 most layer of the bark, we tind the Wood, composed of 
 the Alburnum externally, the Duramen or hard wood 
 toward the interior, and the Pith. The Alburnum is not 
 essentially different from the hard wood, being merely 
 wood in a young state, not yet fully hardened, and gene- 
 rally of a paler colour. In trees of which the wood is 
 very hard and compact, such as Ebony, Logwood, and 
 Laburnum, there is a very marked distinction as to 
 colour between the wood properly so called, and the Al- 
 burnum, the former being much darker; but in trees, of 
 which the wood is soft and white, such as Willows and 
 Pines, there is very little difference in this respect. At 
 the end of some years, the layers of alburnum become 
 converted into wood. This change, however, does not 
 take place with regularity as to time or extent. One 
 part of a layer of alburnum may be seen indurated, while 
 another remains soft; and sometimes a tree is seen to 
 have more layers soft on one side than on another. Once 
 hardened, the woody layers no longer increase in thick- 
 ness or length, and their vessels generally become imper- 
 vious to fluids. The wood is composed of elongated 
 cellular tissue, commonly called Woody Fibre, $ 13, and 
 is traversed by vessels of the kind named Ducts, | 16. 
 The layer nearest the central pith is the oldest, and a 
 new layer is formed each year, in contact with the liber 
 or inner bark. 
 
 69. Inverse Analogy between the Bark and the Wood. 
 There is a beautiful analogy subsisting between the cor- 
 tical and the woody systems. 1. The older layers of the 
 bark are forced outwards, and constitute the cortical
 
 42 
 
 MEDULLARY RATS. 
 
 layers, properly so called. They are the analogue of the 
 heart-wood of the stem, with this difference, that the 
 one undergoes distension, while the other remains as de- 
 posited; the fibres of the one become more or less flexu- 
 ous from pressure beneath; those of the other con- 
 tinue 'rectilinear. 2. Woody layers continue to be 
 sap-wood, till they are converted into heart-wood, and 
 become hard ; cortical layers are distended, half-disorgan- 
 ized before this period, lose their freshness much sooner, 
 and never attain the same degree of solidity. The for- 
 mer always retain their thickness; the latter become 
 thin, from distension and separation of their fibres. The 
 former, sheltered from atmospheric influences, retain 
 their vitality; the latter, exposed to these influences, dry 
 up, split, and assume darker complexions. 
 
 70. The Pith and its Sheath. Within the innermost 
 layer of wood is the Medullary Sheath or Tube, which is 
 formed of ducts intermixed with spiral vessels. Although 
 generally cylindrical, it presents, in its transverse sec- 
 tion, various forms, being angular or elliptical. Once 
 formed, it no longer changes its form or dimensions, but 
 remains the same during the whole life of the plant. 
 The Pith or Medulla, is a spongy substance, formed of 
 cellular tissue, and sometimes longitudinally traversed by 
 a few vessels. Its cellules are larger, and more regularly 
 arranged than those of any other part. In herbaceous 
 plants, in young shoots, and woody stems of the first 
 year, it is green and juicy, like the external herbaceous 
 envelope; but, in the progress of vegetation, it loses its 
 fluids and green colour, and is generally found to be dry 
 and white. In some plants which have a rapid growth, 
 it becomes torn, and nearly disappears, leaving the stem 
 hollow. 
 
 71. Medullary JRays. The thin vertical plates of cel- 
 lular tissue, which are seen passing from the pith or
 
 MONOCOTYLEDONOUS STEMS. 43 
 
 medullary sheath, through the layers of the wood, are 
 what carpenters call the "silver grain." The beauty of 
 the wood, in fact, depends chiefly upon the manner in 
 which it has been cut, whether perpendicularly to the 
 medullary plates, or so as to divide them obliquely. Al- 
 though the plates which proceed from the pith run out to 
 the outermost layer of the wood, yet each successive 
 layer of wood shows additional plates originating from or 
 terminating in it; so that, where there may be twenty 
 plates traversing the innermost layer, there may be 
 twenty times that number traversing the outermost. 
 
 72. Structure of the Honocotyledonous Stem. The 
 woody stem of a monocotyledonous plant (Fig. 11, 6), pre- 
 sents a very different appearance from that of a dicoty- 
 ledonous tree. This kind of stem is not formed of two 
 bodies, increasing in two opposite directions; and its 
 transverse section shows no circular layers of wood, 
 alburnum, liber, and bark; all these parts seeming, as it 
 were, confounded together in it. The interior of such a 
 stem is composed of cellular tissue, traversed by longi- 
 tudinal fasciculi of vessels; and its bark is seldom dis- 
 tinguishable from the rest. In the dicotyledonous stem 
 the hardest part is that nearest the centre; but in the 
 monocotyledonous, that nearest the circumference has 
 most solidity. Such is the structure of the stipe in 
 Palms, and that of other families of this class is more or 
 less analogous, although they present differences. Thus, 
 in Bamboos, and grasses generally, the stem is hollow. 
 
 73. Structure ofi/ie Root similar to thai of the Stem. 
 Reverting to the structure of the root, already described 
 in I 33, it may be remarked, that it generally corre- 
 sponds to that of the stem. Thus, in dicotyledonous 
 trees, a transverse section shows layers of woody tissue, 
 although not so distinctly defined, and a cortical body, 
 together with medullary plates. The pith, however, is
 
 44 BECAPITDLATION. 
 
 wanting, and there are neither spiral vessels nor stomata. 
 In monocotyledonous trees, the root, instead of tapering, 
 is composed of numerous fibres or radicles, issuing 
 from the neck. The root and the stem in all plants form 
 two conical or cylindrical bodies, applied against each 
 other by their bases, and growing by their summits. 
 These bodies branch in opposite directions, the stem 
 dividing upwards, the root downwards. 
 
 RECAPITULATION. 
 
 44. What is meant by the stem ? Are any phanerogamous 
 plants stemless ? What other parts are liable to be mistaken 
 for steins ? Are any kinds of stem apt to be considered as 
 roots? 45. What are the principal kinds of stem? 46. 
 Give an account of the Cormus. 47. What is the Tuber? 
 48. Define the Creeping Stem. 49. Describe the Rhizoma. 
 50. What is meant by the stem properly so called? 51. 
 Describe the Trunk. 52. In what respect is the Stipe 
 different ? 53. What is the nature of the Culm ? 54. Are 
 there any other varieties of the stem ? 55. Distinguish 
 between Herbs, Shrubs, and Trees. Explain any other terms 
 which suggest differences in the consistence of stems. 56. 
 Describe the different characters of trees as produced by the 
 modes of branching. 57. Explain the terms distichous, 
 dichotomous, brachiate, and determinately - branched. 58. 
 What appendages are sometimes found on the stem, in the 
 absence of leaves ? What is meant by a winged stem ? 
 What is meant by glabrous, farinaceous, and glaucous, as 
 applied to the surface of stems ? What is pubescence, and 
 how are its varieties designated ? 59. Distinguish between 
 Thorns and Prickles. 60. Does the internal structure differ 
 much in stems? 61. Of what two bodies are the woody 
 stems of Dicotyledonous plants composed ? 62. Mention all 
 the parts more particularly, commencing at the centre. 63. 
 Give a general account of the Epidermis. 64. What is the
 
 BUDS. 45 
 
 nature of the Herbaceous Envelope ? 65. Describe the Bark. 
 Into how many parts is it divided ? 66. What is the nature 
 of the Liber ? Whence is its name derived ? Describe the 
 process by which the ancients prepared paper. 67. What 
 recent distinctions have been adopted in describing the 
 structure of bark? 68. Describe the Woody layers. In 
 what respect does the Alburnum differ from the Duramen ? 
 Of what is the wood composed ? Which of its layers is the 
 oldest ? 69. Explain the inverse analogy which subsists 
 between the cortical and the woody systems. 70. Give an 
 account of the Pith and its Sheath. 71. Describe the 
 Medullary Plates. 72. In what respects is the Monocoty- 
 ledonous Stem different from the Dicotyledonous ? 73. Has 
 the structure of the Root any relation to that of the stem ? 
 
 CHAPTER VII. 
 BUDS. 
 
 74. Nature of Buds. A JBud, Gemma, is a body com- 
 posed of the rudiments of some of the various organs of 
 a plant generally inclosed within scales, and placed iu 
 
 (Fig. 12.) 
 
 the axilla of a leaf, or at the extremity of a twig. Buds 
 may be divided into subterranean and aerial. According
 
 46 ARRANGEMENT OF BUDS. 
 
 to the organs of which their outer scales are formed, they 
 may be distinguished into : 
 
 1 . Leafy or Foliaceous. Gemmce foliacece. Those of 
 which the scales are leaves that have not been developed; 
 as in Mezereon. 
 
 2. Petiolar. G. petiolacece. When the scales are 
 formed by the persistent bases of the leaf-stalks; as in 
 the Walnut. 
 
 3. Stipular. G. stipulacece. When enveloped by the 
 stipules ; as in the Tulip-tree. 
 
 The scales of buds are always abortive organs, which, 
 having served the purpose of protecting them, shrivel 
 and fall off. 
 
 75. Composition of Buds. According to the different 
 shoots to which they give rise, buds are distinguished 
 into three kinds: 
 
 1. Leaf -Buds. G. foliiferce. Those which give rise 
 to branches bearing leaves only. 
 
 2. Flower-Buds. G. floriferce. Those which produce 
 only flowers. 
 
 3. Mixed Buds. G. misctce. Those which give rise 
 to both leaves and flowers. 
 
 Leaf-buds are generally of an ovate or elongated form ; 
 flower-buds, roundish; and mixed buds of an interme- 
 diate shape. The scales by which buds are enveloped, 
 are frequently covered with resinous or glutinous matter, 
 or with hairs, as if to protect them from the weather. 
 In warm climates, buds are generally destitute of these 
 coverings, and for this reason, among others, the trees 
 of these countries are unable to resist the cold of our 
 winters, and must therefore be sheltered. 
 
 76. Arrangement of Buds. With respect to position, 
 buds are either regular and symmetrical, or irregular 
 and adventitious. The latter arise accidentally and
 
 SUBTERRANEAN BUDS. 47 
 
 without order, after the evolution of the stem and 
 leaves, in the roots, in the midst of the wood, on the 
 edges, and on the surface of the leaves. Regular buds 
 (Fig. 12), are found only at the ends of the branches, or 
 in the axils of the leaves. They begin to form in sum- 
 mer, enlarge a little in autumn, remain stationary during 
 winter, and in spring are gradually developed. The up- 
 permost buds of a branch are those which are usually 
 first developed. Buds may be variously disposed, being 
 opposite to each other in pairs, or alternate, or in whorls ; 
 and upon this circumstance is dependent the division of 
 the stem into branches. But as many of the buds are 
 never developed, branches are not so symmetrically dis- 
 posed as leaves. 
 
 77. Development of Branches. Although, owing to 
 various circumstances, such as an unfavourable situation 
 for receiving moisture, air, or light, a bud may not be 
 developed so as to form a branch, it yet generally con- 
 tinues to live, and being carried outward as the branch 
 enlarges, may, under favourable circumstances, shoot out 
 into a twig. The original direction of the buds deter- 
 mines that of the branches, which may come off from 
 the stem at various angles, 56. 
 
 78. Subterranean Suds. Although the modifications 
 presented by buds, which are developed under the sur- 
 face of the soil, are numerous, it is useless to designate 
 them all by different names ; and, therefore, it will suf- 
 fice here to allude to two kinds, the Turio, and the Bulb. 
 The Turio is the subterranean scaly bud of a herbaceous 
 plant, annually developed, and producing a new stem. 
 Thus, the shoot of the common edible Asparagus is a 
 Turio, as are the young shoots of grasses and other 
 plants having a rhizoma or creeping stem. The Turio 
 differs from the bud, in springing always from a peren- 
 nial root, or rhizoma; that is, its origin is subterranean;
 
 48 BULBILS. 
 
 the bud always grows on a plant exposed to the air 
 and light. 
 
 79. The Bulb is a bud belonging especially to certain 
 perennial herbaceous Monocotyledonous Plants. This 
 organ has usually been mistaken for a root; but the true 
 root connected with it, 40, consists of a Disk or paren- 
 chymatous plate, and a number of fibres or radicles, 
 generally simple. To the disk are attached numerous 
 fleshy scales, enclosing the rudiments of a stem and 
 leaves. The arrangement of the scales gives rise to 
 two kinds of bulbs: 
 
 1. The Coaled or Tanicated Bulb. Bulbus tunicatus. 
 PI. II., Fig. 14. Here the outer scales, which are thin 
 and membranous, form each a continuous covering; as in 
 the Onion, Hyacinth, and Daffodil. 
 
 2. The Scaly or Squamous Bulb. B. squamosus. PI. 
 II., Fig. 15. Here the outer scales are distinct, fleshy, 
 and imbricated, like the inner scales ; as in the White 
 and Orange Lilies. 
 
 Bulbs are generally ovate or globular, and always of 
 annual duration. Sometimes the bulb is simple, as in 
 the Tulip; sometimes multiple, as in the Garlic. The 
 new bulbs, which are developed in the axils of the bulb- 
 leaves, sometimes arise in the centre of the old bulb, as 
 in the Onion; sometimes by its side, as in the Tulip; or 
 above it, as in Gladiolus; or beneath, as in Ixia. 
 
 80. Bulbils. There is a kind of bud, which, although 
 not subterranean, but capable of being developed upon 
 different parts of a plant, is in all essential respects simi- 
 lar to the Bulb, and bears the name of Bulbil. It sepa- 
 rates spontaneously from the stem, and on being placed 
 in favourable circumstances, gives rise to a new plant. 
 Of this kind are the small buds seen in the species of 
 Lily named on that account buttriferum, and in some 
 species of Garlic. These bodies are not to be confounded
 
 FORM, STRUCTURE, ETC., OF LEAVES. 
 
 49 
 
 with Seeds, which have a very different structure, as will 
 afterwards be explained. 
 
 RECAPITULATION. 
 
 74. Define a Bud. How are buds distinguished accord- 
 ing to the organs of which their outer scales are formed ? 
 75. How are they named, with reference to the parts to 
 which they give rise ? What is their general form ? 76. 
 How are buds arranged upon the stem ? 77. Has the direc- 
 tion of the bud any effect upon that of the branches ? 78. 
 Are there any subterranean buds ? Describe the Turio. In 
 what does the Turio differ from the bud ? 79. Give an account 
 of the Bulb. How many varieties of it are there ? Where 
 are the new bulbs formed ? 80. In what respects does the 
 Bulbil differ from the bulb ? 
 
 CHAPTER VIII. 
 FORM, STRUCTURE, AND RELATIONS OF THE LEAVES. 
 
 81. General Idea of the Leaf. Attached to the sides 
 of the stem are certain appendages, named LEAVES, Folia, 
 which are organs of respiration and evaporation. They 
 are almost always green, and are composed of vascular 
 fibres, here named veins or nerves, spread out so as to 
 form a kind of network, of which the interstices are 
 filled with cellular tissue, here termed parenchyma, the 
 whole being covered with the epidermis. Although 
 generally flat, they are sometimes, in succulent plants, 
 cylindrical or of various forms, presenting the appear- 
 ance of solid masses. The vessels which, in Dicotyledo- 
 nous plants, come off from the medullary sheath, being 
 at first close together in bundles, the basal part of the
 
 50 ARRANGEMENT OP LEAVES. 
 
 leaf is narrow, and forms what is called the Petiole, or 
 Leaf-stalk; but they subsequently expand and subdivide, 
 to form the body of the leaf, which is technically named 
 the Limb, or blade. These nerves or veins are composed 
 of the same parts as the stem, namely of spiral vessels, 
 ducts, and elongated cellules. In trees, the two surfaces 
 of the leaf differ in structure and functions, the upper 
 surface being generally smoother, firmer, more glossy, 
 and furnished with fewer stomata; while the lower is 
 duller, of a paler tint, and often covered with hairs. In 
 herbaceous plants, the stomata exist equally on both 
 surfaces. Leaves that float on the water, have them 
 only on their upper surface, and those which are entirely 
 immersed, are destitute of them. 
 
 82. Arrangement of Leaves upon the Stem. 1. Leaves 
 have been named, with reference to the parts of the stem 
 on which they grow, radical, cauline, ramous, and floral; 
 or, more strictly speaking, only cauline and ramous, the 
 former being developed from the stem, the latter from 
 the branches. The radical leaves of botanists are caul- 
 ine leaves, developed so near the root as to appear to 
 arise from this organ, as in Hyacinth; while Jloral 
 leaves are those which grow at the base or in the vici- 
 nity of flowers. 2. Leaves have been named, with re- 
 ference to their succession during vegetation, seminal, 
 primordial, and ordinary. Seminal leaves are formed 
 inside the seed of many plants, and constitute what will 
 hereafter be explained under the term cotyledon. By 
 primordial leaves are denoted those which immediately 
 succeed to the former. PI. II., Fig. 7, represents the 
 early leaves of the Garden Radish: the lower and re- 
 flected pair are the seminal, the interior and erect pair 
 are the primordial leaves. The ordinary leaves are the 
 proper cauline and ramous leaves of a plant. 3. Leaves 
 are also named, with reference to their relation arnctog
 
 ARRANGEMENT OF LEAVES. 51 
 
 themselves, opposite, alternate, whorled, spiral, <fcc. 
 These arrangements are important, being intimately 
 connected with the general symmetry of plants. 
 
 83. 1. Opposite leaves, PI. II., Fig. 6, are those which 
 are developed in pairs, the leaves of each pair heing op- 
 posite to each other, as in Mint. When the pairs alter- 
 nately cross one another, the leaves are said to be decus- 
 sate, as in PI. IV., Fig. 28. 2. Alternate leaves, PI. 
 III., Fig. 21, are those which are developed alternately, 
 the third above the first, the fourth above the second, as 
 in Elm. 3. Whorled leaves, PI. X., Fig. 127, are those 
 which are developed around the stem, in numbers ex- 
 ceeding two, and from the same plane, as in Mare's-tail. 
 When the whorl consists of three leaves, these are said 
 to be ternate; when of four, quaternate; of five, quinate; 
 and so on. 4. Spired leaves are those which consist of 
 more than five leaves, forming regular spires round the 
 stem, as in the Screw-pine. These four arrangements 
 may be reduced to two, namely the wJwrl, which, in its 
 most reduced state, presents opposite leaves; and the 
 spiral, which, under similar circumstances, exhibits alter- 
 nate leaves. 5. Leaves are called fasciculate, PI. IV., 
 Fig. 26, when many are developed together from the 
 same point, as in the Larch. 6. They are imbricated, 
 PI. IV., Fig. 27, when they overlap one another, in the 
 manner of tiles on the roof of a house, and as occurs in 
 
 DESCRIPTION OP PLATE IV. Pig. 26. Tufted Leaves. 
 Tig. 27. Imbricated Leaves. Fig. 28. Decussate Leaves. 
 Fig. 29. Distichous Leaves of Yew. Fig. 30. Unilateral 
 Leaves. Fig. 31. Peltate Leaf of Nasturtium. Fig. 32. 
 Amplexicaul Leaf. Fig. 33. Perfoliate Leaf. Fig. 31. 
 Sheathing Leaf of a Grass. Fig. 35. Equitant Leaves. 
 Fig. 36. Decurrent and Spinous Leaf. Fig. 37. Flower- 
 bearing Leaf of Ruscus.
 
 52 INSERTION OF LEAVES. 
 
 Heath, and in the fleshy leaves of the hulb (PI. II., 
 Fig. 15). They may he biserial, in two rows; triserial, in 
 three; quadriserial, in four. 7. Leaves are distichous, 
 PI. IV., Fig. 29, when they are developed in two ranks, 
 or spreading in two directions, as in Yew. 8. They are 
 unilateral, PI. TV., Fig. 30, when they lean toward one 
 side, as in Solomon's Seal. 
 
 84. Direction of Leaves. With respect to direction, 
 leaves are vertical or perpendicular, in Iris; erect, or 
 forming a very acute angle with the stem, as in Juncus 
 articulatus; close-pressed, when they lie closely upon the 
 stem; spreading, or patent, when they form a moderately 
 acute angle with the stem; horizontal, when they spread 
 at right angles; redinate, inclining downward; recurved, 
 hent backward; incurved, bent inward; pendent, directed 
 downward; reversed, when the petiole is twisted, so that 
 the lower surface is turned upward; depressed, when the 
 radical leaves are pressed close to the ground, as in 
 Plantago media; floating, when lying on the surface of 
 water, as in Water Lily; submersed, when covered by 
 water, as in Hottonia palustris; emersed, when rising 
 out of the water, as in Alisma plantago, &c. 
 
 85. The Petiole. When the bundle of fibres proceed- 
 ing from the stem divides and spreads out at once, so as 
 to occupy a portion of the circumference of the stem, 
 and, being flat and of considerable breadth, not to be 
 distinguishable from the lamina or blade, the leaf is said 
 to be sitting or sessile, Folium sessile, PI. IV., Fig. 30. 
 But when, on the contrary, the bundle of fibres is pro- 
 longed before it expands into a membrane, and thus 
 forms a distinct stalk, the leaf is said to be petiolate, 
 F. petiolatum, PI. III., Figs. 19, 21. Various circum- 
 stances relative to the petiole give rise to several varie- 
 ties of insertion or attachment of the leaves. 
 
 86. Insertion of Leaves. A leaf, whether sessile or
 
 MODIFICATIONS OF SESSILE LEAVES. 53 
 
 petiolate, may be attached to the stem in two different 
 ways. Sometimes the cellular tissue of the leaf is con- 
 tinuous with that of the stem, and sometimes separated 
 from it. In the former case, the leaf, on dying, remains 
 attached to the stem in a withered state. In the latter 
 case, the leaf is affixed by a kind of contraction, at which 
 the fibres are closely united, and the cellular tissue in- 
 terrupted/ Such a contraction is named a joint or articu- 
 lation, and the leaf is said to be articulated. Leaves so 
 attached are caducous, that is, fall off early in winter; 
 and at night they assume a different position from that 
 which they had by day; such leaves occur only in dico- 
 tyledonous plants, while the others are chiefly peculiar 
 to rnonocotyledonous. Sessile leaves present the follow- 
 ing modifications. 
 
 1. Semiampleottcaul. F. semiamplexicaule. When the 
 base of the petiole is expanded, so as to embrace a large 
 portion of the circumference of the stem. 
 
 2. Amplexicaul. F. amplexicaule. PI. IV., Fig. 32. 
 When it embraces the stem iu its whole circumference ; 
 as in the Garden Poppy, Papaver somniferum. 
 
 3. Sheathing or Vaginant. F. vaginans. PI. IV., 
 Fig. 34. When the petiole, besides embracing the stem, 
 is prolonged, so as to form a sheath to it; as in most 
 Grasses. 
 
 4. P& foliate. F. perfoliatum. PI. IV., Fig. 33. 
 When an amplexicaul leaf has its two sides at the base 
 united, so as to appear as if the stem ran through it; as 
 in Bupleurum rotundifolium. 
 
 5. Connate Leaves. Folia connata. PI. III., Fig. 17. 
 When two opposite sessile leaves are united by their 
 bases; as in Chlora perfoliata and Lonicera caprifolium. 
 
 6. Peltate. When the petiole is inserted into the 
 middle of the leaf, and the nerves issuing from it spread 
 out in all directions, the leaf is said to be peltate, or
 
 54 FORM OF TEE PETIOLE. 
 
 shield-shaped, F. peltatum, PI. IV., Fig. 31; as in Hy* 
 drocotyle vulgaris, and Tropceolum majus. 
 
 87. Form of tlie Petiole. The Petiole presents other 
 circumstances, which require to be attended to. Thus, 
 it may be short or long. Viewed with respect to form, 
 it may be round, compressed, three-sided, or of some of 
 the forms described in 58. It may be club-shaped, P. 
 daviformis, enlarged at its upper part; winged, P. alatus, 
 having the leaf prolonged upon it, so as to form a mem- 
 branous border on each side, as in the Orange ; leaf-like, 
 P. foliiformis, when so broad and thin as to have the 
 appearance of a leaf. To this last kind, which exists in 
 many of the Acacias of New Holland, some have given 
 the name of Phyllodium. Very frequently the petiole 
 has a groove along its upper surface, when it is said to 
 be channelled, P. canaliculatus. 
 
 88. The Limb or Blade. According to the different 
 dispositions of the nerves, and the manner in which the 
 parenchyma fills up their intervals, the limb or blade of 
 the leaf assumes a great variety of forms. It will easily 
 be understood, that the form or contour of a leaf is de- 
 termined by the length to which the nerves or their 
 ramifications extend, and that the entireness or indenta- 
 tion of the margin depends upon the degree in which the 
 parenchyma is developed between them. These circum- 
 stances determining the particular form, it is obvious 
 that a distinction into leaves, composed as it were of a 
 single blade, and leaves composed of several pieces, or 
 into simple and compound leaves, is of little real import- 
 ance. A more philosophical distinction is, that a simple 
 leaf has all its parts continuous, whether entire or divided 
 in the greatest degree; while a compound leaf is that 
 which has an articulation, as that of Orange. But 
 as the former distinction is very obvious, and useful in 
 arranging leaves for description, it may be well to retain it.
 
 ANGULINERVED LEAVES. 55 
 
 89. Simple and Compound Leaves. A Simple Leaf is 
 one of which the limb consists of a single piece, PI. V., 
 of which the margin may be entire, PI. V., Figs. 38, 39, 
 or variously indented, Figs. 58, 59, and either sessile, 
 PI. IV,, Fig. 30, or petiolate, PI. II., Fig. 21. A 
 Compound Leaf, PI. VIII., is one composed of several 
 distinct pieces or leaflets, each of which is articulated to 
 the petiole, or connected with it by a narrow part, in 
 which the cellular tissue is wanting. For the reason 
 mentioned above, it will be convenient to speak of the 
 Simple and the Compound Leaves separately. But pre- 
 vious to this, it is of importance to describe the modes 
 of distribution of the nerves. 
 
 90. Nervation of Leaves. By the terms "nervation" 
 and "venation," which are synonymous, is meant the 
 distribution of the vascular fasciculi in the leaf. It is 
 observed that, in monocotyledonous plants, the nerves 
 are generally simple and curved; and that, in dicotyle- 
 donous plants, they are branched and angular. The 
 degree and manner of branching give rise to several re- 
 markable varieties. 
 
 91. Curvinerved Leaves. When the nerves or vascular 
 fasciculi all proceed from the base of the leaf, curve out- 
 wards to either side, assume a degree of parallelism, and 
 traverse the limb in its whole length, the leaf is said to 
 be curvinerved, PL VII., Figs. 89, 90. The nerves 
 sometimes converge toward the tip, as in the figures re- 
 ferred to, or diverge, as in PL V., Fig. 60. 
 
 92. Angulinerved Leaves. In dicotyledonous plants, 
 the nerves, in issuing from the base, separate and form 
 strong veins, PL IV., Fig. 31; or run together, so as to 
 form a midrib, from which veins are given off on either 
 side, PL VII., Figs. 88, 91. In this kind of leaf the fasci- 
 culi subdivide and unite in various degrees, forming a net- 
 work; hence it tears ia an irregular manner, while the
 
 56 FIGURE OF SIMPLE LEAVES. 
 
 curvinerved leaf separates, when force is used, in the 
 direction of the nerves, or from the apex to the base. 
 The following varieties of the angulinerved leaf are de- 
 scribed. 
 
 1. Pennin&rved. PI. VI., Fig. 80; PI. VII., Fig. 
 88. When the midrib or primary nerve, extends from 
 the base to the tip, and emits on either side, in its whole 
 length, secondary nerves, which subdivide in like manner. 
 
 2. Palminerved. PI. VI., Fig. 65. When, instead 
 of forming a midrib, the fasciculi of vessels diverge from 
 the tip of the petiole, forming a number of equally strong 
 nerves, which afterwards subdivide iu the penninerved 
 manner. 
 
 3. Pedatinerved. PI. VIII., Fig. 114. This is a 
 modification of the last, in which there are three princi- 
 pal nerves, those at the sides sending off large branches 
 in the direction of the tip of the leaf. 
 
 4. Peltinerved. PI. IV., Fig. 31. When the fasci- 
 culi diverge from the top of the petiole, radiating all 
 round. 
 
 93. Figure of Simple Leaves. The terms applied to 
 leaves, as designative of the modifications in their out- 
 
 DESCKIPTION OF PLATE V. Fig. 38. Orbicular Leaf. Tig. 
 39. Roundish Leaf. Tig. 40. Ovate Leaf. Fig. 41. Obovate 
 Leaf. Fig. 42. Elliptical Leaf. Fig. 43. Spathulate Leaf. 
 Fig. 44. Wedge-shaped Leaf. Fig. 45. Lanceolate Leaf. 
 Fig. 46. Linear Leaf. Fig. 47. Needle-shaped Leaf. Fig. 
 48. Triangular Leaf. Fig. 49. Quadrangular and Abrupt 
 Leaf. Fig. 50. Deltoid Leaf. Fig. 51. Rhomboidal Leaf. 
 Fig. 52. Kidney-shaped Leaf. Fig. 53. Heart-shaped Leaf. 
 Fig. 54. Crescent-shaped Leaf. Fig. 55. Sagittate Leaf. Fig. 
 56. Hastate Leaf. Fig. 57. Panduriform Leaf. Fig. 58. 
 Runcinate Leaf. Fig. 59. Lyrate Leaf. Fig. 60. Cleft Leaf. 
 Fig. 61. Three-lobed Leaf. Fig. 62. Sinuate Leaf. Fig. 63. 
 Partite Leaf. Fig. 64. Laciniate Leaf.
 
 COMPOUND LEAVES. 57 
 
 line, margin, apex, and surface, are very numerous. 
 Many of these are common terms, and of familiar appli- 
 cation, as orbicular, ovate, elliptical, oblong, <fec. These 
 are figured in PI. V., and the terms are fully explained 
 in the glossary at the end of the volume. Some of these 
 relate to the entire outline of the leaf, some to the base, 
 some to the sides, the point, the margin, and the consist- 
 ence of leaves. 
 
 94. Compound Leaves. The modifications hitherto 
 defined are those of the Simple Leaf, or that of which 
 the limb or blade consists of a single piece. The Com- 
 pound Leaf, or that composed of several distinct pieces, 
 articulated upon a common stalk, presents several varie- 
 ties. The petiole of such a leaf may be simple or 
 branched. When it is simple, the leaf is said to be 
 compound, properly so speaking; but when it is branched, 
 the leaf is doubly compound, or decompound. Agreeably 
 to what has been stated with respect to the arrangement 
 of the nerves or veins of the leaf, 81, 90, it is found 
 that they determine the form assumed by compound 
 leaves, which may be divided into those of which the 
 leaflets diverge from the summit of the petiole, or are 
 palminerved ; and those in which the leaflets come off 
 from the sides of the petiole, or are pinninerved. There 
 are other modifications, which, however, may all be re- 
 ferred to these. 
 
 DESCRIPTION OF PLATE VI. Fig. 65. Palmate Leaf. Fig. 
 66. Pinnatifid Leaf. Kg. 67. Doubly Pinnatifid Leaf. Fig. 
 63. Pectinate Leaf. Kg. 69. Unequal Leaf. Pig. 70. Erose 
 Leaf. Fig. 71. Retuse Leaf. Fig. 72. Emarginate Leaf. 
 Fig. 73. Acuminate Leaf. Fig. 74. Acute Leaf. Fig. 75. 
 Thorn-pointed Leaf. Fig. 76. Cirrose Leaf. Fig. 77. Spinous 
 Leaf. Fig. 78. Ciliate or Fringed Leaf. Fig. 79. Toothed 
 Leaf. Fig. 80. Serrate Leaf. Fig. 81. Crenate Leaf.
 
 58 PINNINERVED COMPOUND LEAVES. 
 
 95. Palminerved Compound Leaves. Of the compound 
 leaves, of which the leaflets diverge from the top of the 
 leaf-stalk, the following are the principal varieties: 
 
 1 . Fingered or Digitate. F. digitatum. When several 
 leaflets, their number not being regarded, proceed from 
 the top of the petiole, as in Trifolium, where there are 
 three, and in ^Esculus Hippocastanum, where there are 
 seven. It may even happen that there is only a single 
 leaflet, and yet the leaf is considered compound, because 
 in other species of the same genus it is clearly so. Ac- 
 cording to the number of leaflets, this kind of leaf is 
 named 
 
 2. Ternate. F. ternatum. PI. VIII., Fig. 106. A 
 digitate leaf, having three leaflets; as in Clover and 
 Wood Sorrel. 
 
 3. Quaternate, of four leaflets; as in Marsilea quadri- 
 folia. Quinate, of five; as in Potentula reptans. Sep- 
 tenate, of seven, as iu JEsculus Hippocastanum. 
 
 4. Pedate. F. pedatum. PI. VIII.,' Fig. 114. A 
 ternate leaf, of which the two lateral leaflets give off 
 others; as in Hdleborus. 
 
 96. Pinninerved Compound Leaves. Of the compound 
 leaves, of which the leaflets come off laterally from the 
 petiole, there are several varieties. There may be one, 
 
 DESCRIPTION or PLATE VIII. Pig. 101. Diversiform 
 Leaves of Mimosa verticillata. Tig. 102. Hooded Leaf of 
 Sarracenia. Fig. 103. Appendiculate Leaf of Dionsea. Fig. 
 104. Articulated Leaf. Fig. 105. Binate Leaf. Fig. 106. 
 Ternate Leaf. Fig. 107. Interruptedly-pinnate Leaf. Fig. 
 108. Lyrately-pinnate Leaf. Fig. 109. Verticillately-pinnate 
 Leaf. Fig. 110. Auriculate Leaf. Fig. 111. Compound 
 Pinnate Leaf. Fig. 112. Doubly Compound, or Biternate 
 Leaf. Fig. 113. Thrice Compound, or Triternate Leaf. 
 Fig. 114. Pedate Leaf of Helleborus.
 
 SUMMARY. 59 
 
 two, three, or more pairs of leaflets, and the leaves are 
 then termed, respectively, conjugate, PI. VIII., Fig. 105, 
 b/jugate, trijugate, &c. Or the leaflets may he developed 
 opposite to each other, in pairs, as in Rose; they are 
 then said to he oppositely-pinnate, PI. IX., Fig. 116; or 
 the leaflets may he alternate, and the leaf termed alter- 
 nately-pinnate; or the leaflets may be in pairs, while the 
 summit of the common stalk ends either abruptly, PI. VIII., 
 Fig. 101, or in a tendril, PI. IX., Fig. 115; these are 
 the abruptly-pinnate leaves. Other modifications occur 
 in the impari-pinnate leaf, in which the petiole of a pin- 
 nate leaf is terminated by a leaflet, as in Rose, PI. VIII., 
 Figs. 108, 110; in the interruptedly-pinnate leaf, in 
 which the leaflets are alternately large and small, as iu 
 Potentilla anserina, PI. VIII., Fig. 107; in the lyrately- 
 pinnoie leaf, in which the terminal leaflet is much larger 
 than the rest, as in Geum rivale, PI. VIII., Fig. 108; 
 and in the verticillately-pinnate leaf, in which the leaflets 
 are finely divided, and seem to embrace the petiole, as in 
 Slum vertitillatnm, PI. VI II., Fig. 109. When the 
 petiole divides into secondary petioles, and these into 
 others, the leaf is said to be decompound, and this may 
 be doubly, PI. VIII., Fig. 112, or thrice, Fig. 113. 
 Lastly, a leaf may be biternate, Fig. 112, or triternate, 
 Fig. 113; bipinnate or tripinnate. 
 
 97. Summary. The whole question connected with 
 the forms of leaves, may be explained by reference to a 
 simple principle. The fibro-vascular tissue ramifies from 
 the petiole, each of its ramifications being invested with 
 parenchyma. These invested ramifications may remain 
 separate from each other, as in the submersed leaves of 
 Ranunculus aquatilis; or they may unite together, more 
 or less, by development of parenchyma, so as to present 
 all the lobed varieties of form. Sinuses, or indentations 
 occurring between the lateral veins, give rise to lobes, or
 
 60 SUMMABY. 
 
 the portions formed by development of the secondary 
 veins. 
 
 1. The adhesion may take place through about half 
 their extent. The projecting portions are called divisions; 
 the sinuses, fissures; and the leaf is pinnati-fid, as in 
 Hawthorn. 
 
 2. The lobes may be still less united by parenchyma, 
 merely at their base; they are then called partitions, 
 and the leaf is said to be pinnati-partite. 
 
 3. The lobes may be altogether unadherent, and are 
 then called segments; the leaf is then said to be pinnati- 
 sected. 
 
 4. The lobes may be isolated at their base, and ad- 
 here at the summit of the leaf, which is then termed 
 lyrale, as in Barbarea vulgaris. 
 
 Sinuses occurring between the tertiary veins, give rise 
 to lobes, which are bi-pinnati/kl, bi-pinnati-partite or, bi- 
 pinnati-sected. Beyond this, accurate division is not cal- 
 culated ; but we have leaves which are termed multi-fid, 
 ladniated, and decompound. 
 
 98. In palminerved and peltinerved leaves, similar 
 remarks apply, excepting that the principal veins of 
 these leaves correspond to the secondary veins of the 
 foregoing. Thus we have leaves which are called 
 
 Palmati-fid, Pelti-fid. 
 
 Palmati-partite, Pelti-partite, or pedati-partite. 
 
 Palmati-sected, Pelti-sected, or pedati-sected. 
 
 In pedati-nerved leaves, the secondary nerves or veins 
 determine the lobes, as in the pinninerved. 
 
 99. In compound leaves a similar explanation may be 
 given. The primary veins may remain distinct from 
 one another, while the remaining branches anastomose, 
 forming as many blades as there are primary veins; this 
 gives us the pinnate leaf. Or the primary and the
 
 COLOUR AND DURATION OF LEAVES. 61 
 
 secondary veins may be distinct, presenting the bi-pinnate 
 leaf, from consolidation of the remaining ramifications. 
 This principle may be extended to the tri-pinnate and 
 further divisions of the leaf. 
 
 100. Surface of Leaves. With regard to the pubes- 
 cence, or hairs, on the surface of leaves, it will suffice to 
 refer to what has already been said on the subject, 21, 
 58 ; but there are other circumstances which require to 
 be pointed out. Many of the terms applied to the sur- 
 face of the stem, |-58, such as even, smooth, glossy, powdery, 
 watery, spotted, and striated, apply equally to that of the 
 leaves. They are also said to be veiny, PI. VII., Fig. 
 88, when the vessels are branched, and prominent, form- 
 ing a network; nervous or ribbed, PI. VII., Fig. 89, 
 when they extend in undivided longitudinal lines ; vein- 
 less or ribless, when destitute of prominent vessels. 
 Three-ribbed, PI. VII., Fig. 90, when they present 
 three distinct ribs from the base to the apex; three-ribbed 
 at the base, PI. VII., Fig. 91; and trirjly-ribbed, PI. VII., 
 Fig. 92, when a pair of large ribs come off from the 
 midrib above the base. 
 
 101. Colour and duration of Leaves. As has been 
 already mentioned, the colour of leaves is generally 
 
 DESCRIPTION OF PLATE VII. Tig. 82. Doubly Crenate 
 Leaf. Kg. 83. Jagged Leaf. Fig. 84. Wavy Leaf. Fig. 
 85. Plaited Leaf. Fig. 86. Undulated Leaf. Fig. 87. Curled 
 or Crisp Leaf. Fig. 88. Angulinerved Leaf. Fig. 89. Curvi- 
 nerved Leaf. Fig. 90. Three-nerved Leaf. Fig. 91. Pinni- 
 nerved Leaf. Fig. 92. Triply-nerved Leaf. Fig. 93. Cylin- 
 drical and Pointed Leaf. Fig. 94. Semicylindrical Leaf. 
 Fig. 95. Awl-shaped Leaf. Fig. 96. Doubly tubular Leaf of 
 Lobelia. Fig. 97. Canaliculate Leaf. Fig. 98. Dolabriform 
 or Hatchet-shaped Leaf. Fig. 99. Three-edged Leaf. Fig. 
 100. Four-edged Leaf.
 
 62 APPENDAGES OF LEAVES. 
 
 green, but of various tints. In the same species the 
 tint varies in the course of its growth and decay. Very 
 frequently the two surfaces of a leaf are of different tints, 
 and sometimes, as in Cydamen Europceum, conspicuously 
 so. Sometimes, as in Arum maculatum, the leaves are 
 patched or spotted with a darker or lighter colour. 
 Leaves may also be parti-coloured in irregular masses; 
 but this is generally a result of cultivation. 
 
 According to the periods during which leaves remain 
 on the stem, they are named: 
 
 1 . Caducous. F. caduca. When they fall soon after 
 their development; as in some species of Cactus. 
 
 2. Deciduous. F. decidua. When they fall before 
 the next spring; as in the Elm and Ash. 
 
 3. Marcescent. F. marcescentia. When they wither 
 before falling; as in the Oak and Beech. 
 
 4. Persistent. F. persistentia. When they remain 
 longer than a year; as in Pines. 
 
 102. Appendages of Leaves. Under this head may 
 be included Stipules, Spines, and Tendrils. 
 
 The Stipule is a small leaf-like appendage to the leaf. 
 It is commonly situated at the base of the petiole, in 
 pairs, as in PI. IX., Figs. 116, 122, either adhering to 
 it, or standing separate. It is usually of a more delicate 
 texture than the leaf, but varies in this respect, as well as 
 in form and colour. In describing it the terms used for 
 the leaf are employed. Stipules are generally considered 
 as analogous to the leaves, or accessory to them, and 
 are sometimes transformed into leaflets. Very few 
 monocotyledonous plants have stipules; and the mem- 
 branous part at the top of the sheath in grasses, although 
 by many considered as such, seems to be of a different 
 nature. 
 
 103. Tendrils. The Tendril., Cirrus, PI. IX., Fig. 
 122, is a prolongation of the petiole into a filiform body,
 
 VERNATION. 63 
 
 which by clasping objects, serves to support plants which 
 have weak stems. Some tendrils, however, as in the 
 Cucumber, are altered stipules; and others, as in the 
 Vine, are transformed branches or flower-stalks. 
 
 104. Spines. The Thorn, which is also named Spina, 
 has been already described as an altered branch; but 
 the spine here alluded to is considered as an alteration of 
 the leaf or petiole. The spines which project from the 
 edges of leaves, as in the Holly and Thistle, are clearly 
 seen to be the extremities of the vascular fasciculi; and 
 in the Barberry, the gradual transformation of the leaves 
 into spines may be distinctly traced. 
 
 105. The Pitcher. A very curious body, called the 
 pitcher, appears to be a modification of the petiole and 
 leaf, the body of the pitcher being the petiole, and the 
 lid the leaf. When in its most perfect state, as in the 
 Pitcher Plant, Nepenthes destittatoria, this is not so ob- 
 vious, and it might be mistaken for a distinct organ, 
 especially as it secretes a fluid. But in Sarracenia, 
 PI. VIII., Fig. 102, and more especially in Dioncea mus- 
 cipula, Fig. 103, the transformation is obvious. 
 
 106. Vernation. Having described the leaves suf- 
 ficiently in detail to afford a pretty comprehensive know- 
 ledge of them, I may now say a few words respecting 
 the manner in which they are folded up in the bud, pre- 
 viously to its expansion. This is named Vernation, while 
 the folding of the parts of the flower is named 
 
 DESCKIPTION OF PLATE IX. Tig. 115. Stipules, also 
 Binate Leaf, with a tendril. Tig. 116. Stipules and Pinnate 
 Leaf of Rosa. Pig. 117. Bractea of Tina. Pig. 118. Brae- 
 teas of Lavandula. Pig. 119. Spinous Bracteas of Atractylis. 
 Pig. 120. Thorns of Hippophae. Pig. 121. Aculei, or Prickles 
 of Rosa. Pig. 122. Cirrus, or Clasper. Pig. 123. Glandule- 
 tipped Hairs of Rosa. Pig. 124;. Hairs. Pig. 125. Bristles.
 
 64 
 
 GENERAL REMARKS. 
 
 ration. The principal varieties of the former are the 
 following: 
 
 (Fig. 13.) 
 
 b 
 
 \.Conduplicate. Vernatio conduplicativa. (Fig. 13, a). 
 The leaf folded lengthwise, one-half applied against the 
 other, so that their margins correspond, as in PhUadd- 
 phus coronarius. 
 
 2. Revolute. V. revoluta. b. Rolled backwards at 
 the sides; as in Rosemary. 
 
 3. Involute. V. involuta. c. Rolled forwards; as in 
 the Apple. 
 
 4. Obvolule. V. dbvoluta. d. When two condupli- 
 cate leaves clasp each other. 
 
 5. Cirdnate. V. circinata. e. Rolled from the tip 
 downwards. 
 
 6. Plicate. V. plicata. f. Folded lengthwise in 
 several plaits; as in Alchemilla. 
 
 7. Equitant. V. equitans. g. Overlapping each other 
 alternately and entirely; as in Iris. 
 
 8. Imbricate. V. imbricata. h. Overlapping each 
 other, so that the middle of the outer leaf is opposite to 
 the edges of two inner. 
 
 107. General Remarks. Many of the terms applied 
 to the leaves, are equally applicable to other organs of a 
 similar nature, as the Bractea, Calyx, and Corolla. 
 When a leaf is not precisely of any of the forms de- 
 scribed above, such as ovate, but appears intermediate 
 between that and another, such as lanceolate, it is denned 
 by combining the two terms, ovato-lanceolate. The
 
 KECAPITULATIOX. 65 
 
 leaves often gradually pass into the Bradece or floral 
 leaves, presently to be described. In fact, tbe Leaves, 
 the Bractese, and the different parts of the flower, namely, 
 the Sepals, the Petals, the Stamens, and the Ovary, are 
 merely modifications of one and the same organ. 
 
 RECAPITULATION. 
 
 81. "What is the nature of Leaves ? Are they always flat ? 
 What is the basal part of the leaf called ? What name is 
 given to the expanded part ? Of what are the fibres of the 
 leaf composed? What difference do leaves present with 
 respect to their stomata? 82. What terms are applied to 
 leaves with reference to the parts of the stem on which they 
 grow ? Are any of these terms inaccurate ? What terms 
 are used with reference to the succession of leaves during 
 vegetation ? Explain the terms seminal, primordial, and 
 ordinary, as applied to leaves. 83. Distinguish between 
 opposite and alternate leaves ; between whorled and spiral 
 leaves. How may these four arrangements be reduced to 
 two ? What is meant by the terms fasciculate, imbricated, 
 decussate, distichous, and unilateral, as applied to the arrange- 
 ment of leaves? Si. How are leaves named with reference 
 to their direction? 85. When the petiole is not distinguish- 
 able from the limb, what is the leaf said to be ? What is a 
 petiolate leaf? 86. What is an articulated leaf? Are any 
 leaves not articulated ? What is meant by caducous ? What 
 are the principal modifications of sessile leaves ? Distinguish 
 between the perfoliate and connate leaves. What is a 
 peltate leaf ? 87. Does the petiole vary in length ? or iu 
 form? What is a winged petiole? Is the petiole often 
 channelled ? 88. What is the limb ? Is its form affected 
 by the nerves ? 89. Define a simple leaf. What is a com- 
 pound leaf ? 90. What is meant by Nervation? 91. How 
 many kinds of nervation are there ? Define a curvinjrved 
 leaf. 92. What is an aiiguiinerved leaf? How many 
 varieties of it are there ? 93. What are the principal terms
 
 66 INFLORESCENCE. 
 
 applied to leaves considered as to their figure or contour ? 94. 
 Define a compound leaf. What are the principal kinds of 
 compound leaves ? 95. Mention some varieties of palminerved 
 compound leaves ? 96. How many kinds of pinnate leaves 
 are there ? What are decompound and supradecompound 
 leaves ? 97. Upon what principle may the numerous forms 
 of leaves be explained ? 98. What is meant by lobes, divi- 
 sions, fissures, and partitions of leaves ? 99. Explain the prin- 
 ciple of pinnation in leaves. 100. What terms apply to the 
 surface of leaves ? 101. Are leaves of any other colour than 
 green? Is the duration of leaves various? 102. Give 
 some account of the Stipule. 103. What is the Tendril? 
 104. How are Spines formed? 105. What is the Pitcher? 
 106. What is meant by Vernation ? Mention some of its 
 principal varieties. 
 
 CHAPTER IX. 
 INFLORESCENCE, OR THE MODE OF FLOWERING. 
 
 108. General Remarks. The term inflorescence de- 
 notes the manner in which the flowers are arranged on 
 plants. It relates, not to flowers, but to flower-stalks. 
 Owing to the great diversity of aspect which inflorescence 
 gives to plants, and the prominent characters which it 
 affords, it requires especial attention. Under this head 
 is included, not only inflorescence, properly so called, but 
 an account of peduncles, pedicles, and bracts, with their 
 modifications. Each flower of a bunch is supported on 
 a little stalk, called a pedicle; the main stalk which sup- 
 ports all the flowers of a bunch and their pedicles, is 
 called the peduncle. The pedicles, therefore, are the 
 branches of a peduncle. What a petiole is to a leaf, a
 
 POSITION AND RELATIONS OF THE PEDUNCLE. 67 
 
 pedicle or a peduncle is to a flower; and, as the presence 
 or absence of a petiole constitutes a petiolate or a sessile 
 leaf, so the presence or absence of a peduncle or a pedicle 
 constitutes a pedunculate or pedicellate, or a sessile flower. 
 In describing these organs, it will be convenient to call 
 the peduncle the central or primary axis of inflorescence ; 
 the first divisions or branches of the peduncle, secondary 
 axes; the next divisions, tertiary axes. A peduncle is 
 distinguished from all other axes, by never bearing true 
 leaves; the small, notched, leaf-like, membranous organs 
 found on the axes of inflorescence, are not leaves, but 
 bracts, or, as they are sometimes called, floral leaves. 
 
 109. Position and Relations of tJie Peduncle. Accord- 
 ing to its situation, the flower-stalk is named radical, 
 when it proceeds from the axil of a radical leaf, 82, as 
 in the Primrose and Cowslip. The radical peduncle is 
 thus synonymous with the Scape of Linua3us, which is 
 defined a stem or stalk that supports one or more flowers, 
 but is destitute of leaves. But some botanists distinguish 
 from the radical peduncle the scape, confining the latter 
 term to the peduncle which arises directly from a radical 
 bud, or from the midst of an assemblage of radical leaves; 
 as in Hyacinth. The peduncle is also named cauline, 
 when it springs directly from the stem; rameal, when it 
 springs from the branches; petiolar, when united with 
 the leaf -stalk; epiphyllous, when it springs from the sur- 
 face of a leaf; as in Ruscus aculeatus; PI. IV., Fig. 37; 
 axillar, when it grows from the axil of a leaf, that is, 
 between the stem or branch and the base of the leaf, 
 or its stalk; as in Anchusa sempervirens; extra-axillar, 
 when it arises beside the leaf; as in Solanum dulcamara; 
 and terminal, when it is placed on the tip of a stem or 
 branch, of which it appears to be the termination, as in 
 Centaurea scabiosa. 
 
 Several other terms are applied to the peduncle> ac-
 
 68 INVOLUCRE. 
 
 cording to its relations. Thus, it may be solitary, either 
 single on a plant, as iu Rubus Chamcemoriis, or single 
 in several parts of the same plant, as in Antirrhinum 
 epurium. When several peduncles grow together, they 
 are said to be clustered, or aggregate. When they are 
 irregularly dispersed over the stem, they are termed 
 scattered. A peduncle may bear one, two, three, or 
 more flowers, and it is then called, respectively, uniftoral, 
 bifloral, trifloral, multifloral. 
 
 110. Tlie Bractea. As the stipule i-s a kind of leafy 
 appendage to the leaf, so the bractea is a kind of leaf 
 connected with the flower, or attached to its stalk. In 
 a general point of view, there is no precise limit between 
 the leaf and the bractea. When the leaves gradually 
 become smaller toward the flowers, without undergoing 
 much alteration of form or colour, they are sometimes 
 named Floral Leaves. In general, bractese may be dis- 
 tinguished from leaves, by their being placed close to 
 the flower, by their smaller size, different form and 
 colour, and thinner texture. It is very seldom that a 
 plant is destitute of bractese, which, however, is the case 
 in those belonging to the natural family of the Crucifcrse, 
 such as the Cabbage and Mustard. As these organs vary 
 in form", colour, and consistence, they are individually 
 described in the same manner as the leaves. Thus a 
 bractea may be lanceolate, ovate, or oblong; green, red, 
 or purple; membranous, leafy, petaloid, or woody. The 
 bractese present several remarkable modifications, which 
 require separate consideration. 
 
 111. Modifications of the Bractece. Under this head 
 are included parts, which by many authors have been 
 considered as belonging to the Flower properly so called. 
 The following are modifications : 
 
 1. The Involucre. Involucrum. PI. XL, Fig. 143. 
 When the bractese, or florul leaves, are so disposed round
 
 CUPULE AND SPATHA. 69 
 
 one or more flowers, as to form a kind of envelope, they 
 are collectively named an Involucre. Such an envelope 
 may consist of three, four, five, or more leaves, and is 
 then named triphyttum, tetraphyllum, pentaphyllwn, poly- 
 phyUum. In the plants named Compound, such as the 
 Thistle and Dandelion, the involucre is formed of nume- 
 rous leaves, usually imbricated, which surround the 
 expanded top of the peduncle, here named the Receptacle, 
 or Anihophore, PI. XVI., Fig. 209. In the plants 
 named Umbellate, as the Carrot and Hemlock, where the 
 peduncles, of which several come off together, branch 
 in the same manner, the leaflets at the base of the 
 peduncles are named the Involucre, while those at the 
 base of the pedicels are named the Involucds, PI. X., 
 Figs. 137, 138. 
 
 2. The Cupule. Cupula. When the bractese are 
 disposed close together around the flower, and remain, 
 enlarging until the fruit is mature, as in the Oak, they 
 are collectively named the Cupule, which may be of 
 several kinds. When the bractea? are small and scale- 
 like, they form the cup of the Oak. They may be leafy, 
 as in the Hazel; or of firm texture, and entirely covering 
 the fruit, as in the Beech and Chestnut. 
 
 3. T/ie Spatha. When the bractea, or involucrum, is 
 very large, membranous, and encloses the flowers pre- 
 vious to expansion, as in Arum and Narcissus, it is named 
 a Sheath or Spatha, PI. XII., Fig. 147. 
 
 Many other modifications might be adduced; but it 
 will suffice to mention one of the most remarkable, that 
 which occurs in the Grasses. 
 
 112. Bractece in the Grasses. The plants to which we 
 give the name of Grasses, such as Wheat, Oats, and 
 Rye-Grass, present a peculiararrangement of the bractese, 
 which assume the place of the calyx and corolla. A 
 great diversity of opinion has taken place regarding the
 
 70 INFLORESCENCE AND WHORL. 
 
 nature and nomenclature of these organs. They may, 
 however, be described thus. PI. XII., Fig. 148. Ex- 
 ternally are two opposite, thin bractese, one placed a little 
 above the other. Within these are two smaller, also op- 
 posite organs of a similar nature, one of them often fur- 
 nished with an awn, or long rigid and twisted bristle-like 
 body. Within these, at the base of the s,eed, or its germ, 
 are two or three minute, generally fleshy scales. The 
 outer scales, or valves, are by some considered the calyx, 
 the inner as the corolla, and the innermost as nectaries. 
 Others regard the outer as bractese, the inner as the 
 calyx, and the innermost as the corolla. Others consider 
 all these parts as bractese. Professor Lindley namea 
 the outer scales glumce; the inner, palece; and the 
 minute scales, squaimdce. In Carex, two bracts become 
 confluent at their edges, and enclose the pistil; the 
 single body formed by this cohesion, is called urceoliis. 
 
 113. The Inflorescence. Leaving the consideration of 
 the Flowers for the next chapter, we have here to de- 
 scribe the manner in which they are arranged. The 
 circumstances of flowers being solitary, terminal, lateral, 
 or axiUar, will be understood from what has been said of 
 the peduncle, \ 109. The principal varieties presented 
 by tbe arrangement of the flowers upon the stem, or its 
 continuation, are the following: 
 
 1. The Whorl. Verticillus. PI. X., Fig. 127. When 
 the flowers surround the stem; as in Hippuris vulgaris. 
 Many authors include under this head the flowers of the 
 
 DESCRIPTION OP PLATE XI. Tig. 139. Cyme of Laurus- 
 tinus. Fig. 140. Panicle of Avena. Fig. 141. Thyrsus. 
 Fig. 142. Calyx of Dianthus, Fig. 143. Involucrura of 
 Anemone. Fig. 144. Sori and Indusia of a Fern. Fig. 145. 
 Indusium and Sorus; also, Capsule and Ring of a Fern. 
 Fig. 146. Catkiii of Hazel, with separate bracteee aud stamens.
 
 SIMPLE MODES OF INFLORESCENCE. 71 
 
 Labiatce, or such plants as the Dead Nettle, PI. X., 
 Fig. 126. But in this case, the flowers grow in two oppo- 
 site clusters in the axils of the leaves, and thus do not 
 surround the stem. These clusters have been named 
 vertidllastri, or false whorls. Whorled flowers never 
 occur, except in cases in which the leaves are whorled. 
 
 114. SIMPLE MODES OF INFLORESCENCE. The follow- 
 ing are the kinds that present the most simple arrange- 
 ment: 
 
 2. The Spike. Spica. PI. X., Figs. 129, 130, 131. 
 When a common unbranched peduncle bears numerous 
 flowers, which are either sessile, or have pedicels so short 
 as to be inconspicuous. Wheat, Barley, Rye, and the 
 Orchises afford examples of this kind of inflorescence, in 
 which the lower flowers are always first developed, and 
 the upper follow in succession. In the spike the flowers 
 may be arranged spirally, or all round, or inclining to 
 one side, or on two opposite sides. In grasses, the di- 
 visions of the inflorescence are terminated by Spikelets, 
 Spiculce, PI. X., Fig. 131. 
 
 3. Tlie Raceme. Eacemus. PI. X., Fig. 128. When 
 a common unbranched peduncle bears numerous flowers, 
 which are furnished with pedicels; as in Ribes nigrum, 
 and R. rubrum. 
 
 DESCRIPTION OF PLATE X. Fig. 126. Spurious Whorl of 
 Lamium. Fig. 127. Verticillate Flowers and Leaves of Hip- 
 puris. Fig. 128. Raceme of Currant. Fig. 129. Spike, uni- 
 lateral, of Ophrys spiralis. Fig. 130. Spicate Raceme of 
 Veronica spicata. Fig. 131. Spikelet of Bromus. Fig. 132. 
 Corymb. Fig. 133. Corymbose Fasciculus of Achillaea. Fig. 
 134. Fasciculus of Diantlms Armeria. Fig. 135. Capitulum, 
 or Condensed Raceme. Fig. 136. Sertule, or Simple Umbel. 
 Fig. 137. Simple Umbel and Involucrum. Fig. 138. Com- 
 pound Umbel, with general and partial Involucres.
 
 72 COMPLEX MODES OP INFLORESCENCE. 
 
 4. TJie CapUulum. PI. X., Fig. 135. This is merely 
 a very short spike, of which the flowers are placed close 
 together; as in Clover. 
 
 5. The Corymb. Corymbus. PI. X., Fig. 132. When 
 in a -raceme, or spike, the stalks of the flowers become 
 gradually longer, from the highest to the lowest, so that 
 all the flowers stand on nearly the same level; as in the 
 Wall-flower and Cabbage. 
 
 G. The Catkin. Amentum. PI. XI., Fig. 146. When 
 the flowers of a spike have bractesa in place of the calyx 
 and corolla, and either after flowering or ripening, the 
 whole falls off in a single piece; as in Willows and Alders. 
 
 7. The Spadix. When the flowers are closely ar- 
 ranged round a fleshy peduncle, and inclosed in a spatha; 
 as in Palms and Arums. 
 
 8. The Anifvodium. When in place of a common 
 stalk, there is a broad convex or flattened surface, on 
 which numerous sessile flowers are arranged, the whole 
 being inclosed within an involucre, as in the plants named 
 Composite, such as the Daisy and Thistle. The flowers, 
 or florets, of the outer ciicle, which generally differ in 
 form from the rest, and are larger, are named florets of 
 the ray, while the others are named florets oftlte disk. 
 
 9. Tlie Sertuk. Sertula. PI. X., Fig. 136. When 
 from the summit of the peduncle proceed several, gene- 
 rally elongated pedicels, nearly of equal length, each 
 bearing a flower; as in Allium ursinum. By many 
 authors this kind of inflorescence is termed a simple um- 
 bel. But the application of a distinct name to it is cen- 
 sured; although, on the same grounds, the use of raceme 
 and corymb ought to be rejected, these modes of in- 
 florescence being merely modifications of the spike. 
 
 115. MORE COMPLEX MODES OF INFLORESCENCE. The 
 above varieties may be considered as simple, while the 
 following are compound,
 
 UMBEL, PANICLE, THTRSUS, AND FASCICLE. 73 
 
 10. Tlie Umbel, Umhdla. PI. X., Fig. 138. When 
 from the summit of the stalk proceed several stalks or 
 rays, of nearly equal length, each of which gives rise to 
 a number of rays, bearing flowers. This is what is 
 called a Compound Umbd, and is the general mode of 
 inflorescence in the family of plants named Umbdlifercs. 
 In a very few of these plants, however, the umbel is 
 simple, and resembles the sertule above described. The 
 primary rays are collectively named the Umbel, the 
 secondary the UmbeUuIe', the bracteee at the base of the 
 former constitute the Involute, and those at the base of 
 the latter, the Involucel. 
 
 11. Tlte Panicle. Panicda. PI. XL, Fig. 140. 
 This may be considered as a compound Raceme. When 
 the main stalk gives off, instead of single flowers, branches 
 bearing several flowers, and subdividing in various de- 
 grees, we have a Panicle; as in the Oat, and many other 
 Grasses. 
 
 12. The Thyrsus. PL XL, Fig. 141. When a 
 panicle is very dense, and of an oblong or pyramidal 
 form; as iu the Lilac, Privet, and Horse-chestnut. 
 
 13. The Cyme. Cyma. PL XL, Fig. 139. When 
 from a single poin't proceed several branches, each of 
 which subdivides irregularly, bearing numerous flower?, 
 placed nearly on a level; as in the Elder. 
 
 14. The Fascicle. Fasciculus. PL X., Fig. 134. 
 When peduncles variously subdivided into short pedicels, 
 bear numerous flowers collected into a close bundle, and 
 nearly level at the top; as in Sweet- William. 
 
 In describing plants, adjectives derived from the above 
 terms are often employed; for example, Corymbose 
 flowers, Umbellate, Fasciculate, Panicled, Racemose. 
 
 116. General Remarks. In all the above modifica- 
 tions of the Spike and Umbel, the flowers are developed 
 from below upwards, or from without inwards, the upper-
 
 74 DEFINITE AND INDEFINITE INFLORESCENCE. 
 
 most or central flower being the last to expand. But in 
 the cyme, the central flowers are first developed, and to 
 this mode of inflorescence may be referred the dichoto- 
 mous stem, in which at each bifurcation is situated a 
 pedicellate flower. In this case it may be said that the 
 stem, in place of bearing flowers on its sides only, and 
 being capable of indefinite prolongation, is terminated by 
 a central flower, having at the base of its pedicel, bractea3, 
 usually two in number, which from their axils produce 
 two new branches, each with a terminal flower; and so 
 on indefinitely. 
 
 117. Definite and Indefinite Inflorescence. The varie- 
 ties of inflorescence may all be reduced to two classes, 
 namely, 
 
 1. Definite or Determinate Inflorescence. 
 
 2. Indefinite or Indeterminate Inflorescence. 
 
 In definite inflorescence, the evolution of the flowers 
 commences with the terminal flower of the primary axis, 
 g 1(J8; then the terminal flowers of the secondary axes 
 open, in the direction from the summit or centre of the 
 inflorescence to the base or circumference; then the 
 lateral flowers which terminate the tertiary axes, pro- 
 ceeding also from the summit to the base. This is 
 termed centrifugal evolution, PI. XI., Fig. 139. 
 
 118. In indefinite inflorescence, the evolution of the 
 flowers commences from the base or margin of the in- 
 florescence, and proceeds to the summit or centre. This 
 is termed centripetal evolution, PI. X., Fig. 130. 
 
 119. The Cyme may be taken as the type of definite 
 inflorescence. In chick-weed and in most caryophylla- 
 ceous plants, a series of bifurcations is found, in the 
 centre of each of which is a solitary flower which termi- 
 nates the inflorescence in each axis. This is the dicho- 
 tomous and simplest form of the Cyme. In the genus 
 Euphorbia this principle is extended, and there may be
 
 SPIKE. 75 
 
 a whorl of three, four, or five bracts, giving rise to a 
 trichotomous, tetrachotomous, or pentachotomous cyme. 
 In some plants, as Echium, Drosera, <fcc., one of the 
 axes of each bifurcation is not developed; the flowers are 
 then found all on one side, and the inflorescence becomes 
 curled, presenting unilateral flowers. This is the scor- 
 pioidal cyme. The Fascicle belongs to the definite inflo- 
 rescences, and may be described as a contracted cyme, 
 in which the lateral branches are very short, as in Sweet- 
 William. 
 
 120. The Spike and the Raceme may be taken as types 
 of indefinite inflorescence. The spike is formed of sessile 
 flowers situated in the axils of several bracts, as in Plan- 
 tain. It admits of the following modifications: 1. The 
 Catkin is a spike composed exclusively of male or of 
 female flowers, which dries up and falls after flowering. 
 There is less difference between the catkin and the spike 
 than appears at first sight; in the same species of Wil- 
 low the male flowers are often found arranged in a 
 catkin or caducous spike, the females in a persistent 
 spike. Some catkins have flowers with short pedicles, 
 like racemes. In Pines we have branching catkins; 
 that is, a central branch and several lateral branches. 2. 
 The Cone is a spike in which the floral organs are ex- 
 tremely hard, persistent, and placed together closely like 
 overlapping scales. The bracts constituting the cone are 
 capable of enlarging after flowering, so as to appear an 
 entire body. The female spike of the Hop is a kind of 
 cone with membranous bracts. 3. The Spadix is a spike 
 enveloped in one large sheathing bract, called a spatha. 
 The spadix is simple in Arum; sometimes its whole ex- 
 tent iis covered with flowers, sometimes its summit is 
 naked. In Palms this spike branches, and is enveloped 
 in an enormous bract; it is then called by the French, 
 regime. 4. The Spikelet or locusta is a small lateral
 
 76 RACEME. 
 
 spike, several of which are arranged around a central 
 indefinite axis or rackis, in Grasses. The flowers of the 
 spikelet are generally alternate, and compactly arranged 
 along the axis. It is usual to terra the inflorescence 
 spiked, when the spikelets are arranged in a spike, as in 
 wheat; panided, when the spikelets are arranged in a 
 panicle, as in millet. 
 
 121. The Raceme differs from the Spike only in the 
 greater length of its pedicles. The flowers of the latter 
 are said to he sessile ; those of the former pedicellate, 
 as in hyacinth. To this must be added, that the pedicles 
 are all of nearly equal length. The raceme admits of the 
 following modifications: 1. The Corymb is a raceme in 
 which the lower pedicles are so long that their flowers 
 are elevated to the same level as that of the uppermost 
 flowers. The inflorescence resembles an inverted cone. 
 It might be mistaken for the fascicle, if the evolution of 
 the latter were centripetal, instead of being centrifugal. 
 2. The Umbel is apparently remote from the raceme, but 
 it is not really so. The pedicles are formed from one 
 point, and the flowers present a plane, a convex, or a con- 
 cave surface. If each of the pedicles bears a single 
 flower that is, if the secondary axes do not divide we 
 have the simple umbel of astrantia : if the pedicles divide, 
 and bear other umbels, we have the compound umbel of 
 heraeleum. Among racemes there is an ornithogalum, 
 with a very long axis ; there are others with a very short 
 axis; there are plants in which the axis is so short that the 
 pedicles appear all to spring from the summit, as in iberis; 
 so that an umbel may be considered as a raceme, of which 
 the axis is almost reduced to nothing. 3. In the Capi- 
 tulum, the flowers of a simple umbel are deprived of their 
 pedicles, and placed close together upon an enlarged axis, 
 called the receptacle. If the receptacle is flat, and sur- 
 rounded by an involucrum, the inflorescence of the com-
 
 INTERMEDIATE KINDS OF INFLORESCENCE. 77 
 
 positse is produced. In these plants, the flowers of the 
 circumference are usually ligulate or strap-shaped, and 
 are called florets of the ray; those in the centre are usually 
 tubular, and are called florets of tfte disk. 
 
 122. The Raceme admits of several decompositions, 
 more or less regular. 1. The Panicle is a raceme, which, 
 instead of hearing single flowers, bears branches of 
 flowers; or, in other words, the secondary axes ramify, 
 as in the simple panicle of poa. When the rachis itself 
 separates into irregular branches, so that it ceases to he 
 an axis, as in some oncidiurns, this is termed a deliquescent 
 panicle. 2. The Thyrsus is a panicle, of which the lower 
 branches are shorter than those of the middle, and the 
 panicle itself is very compact. 
 
 123. Combinations of Inflorescence. These are nu- 
 merous. Spikelets of grasses are often panided. Carex 
 has flowers in compact spikes arranged along a central 
 axis in racemes. Papyrus has flowers in Spikelets, which 
 are stalked and arranged like umbels. In Juncus, flowers 
 occur in capittda, arranged in short panicles. The 
 primary arrangement may be simple or compound; the 
 secondary may resemble, or diifer from that of the cen- 
 tral axis. Again, the inflorescence of the male flowers 
 frequently differs from that of the female, in the same 
 plant. The males of the mais are arranged in a branch- 
 ing spike; the females in a simple spike. The males of 
 the pine are in catkins, the females in cones. The males 
 of the hop are panided; the females are in a kind of 
 cone or spike. The flowers of hura crepitans proceed 
 from the same axil : the females are solitary, the males 
 are spilced. Generally speaking, in these cases of dis- 
 parity, the male flowers are more scattered and on the 
 longer stalks. 
 
 124. Intermediate kinds of Inflorescence. In some 
 species of digitalis, and other plants, the lower flowers are
 
 78 RECAPITULATION. 
 
 solitary, and situated at tolerable distances from one 
 another, and are within the axils of large leaves ; while 
 the upper flowers are very close to one another, and 
 situated within the axils of minute bracts. This inter- 
 mediate kind of inflorescence is termed the spike or 
 raceme, interrupted at its base, or leafy at its base. 
 Varieties occur, depending upon the more or less rapid 
 transformation of the floral leaves into bracts, and the 
 approximation of the flowers. Some inflorescences con- 
 sist of a spike above and a raceme below ; or are spikes 
 at an early period, and racemes at a later. Several spikes 
 clustered together constitute a ramose spike, as in Statice 
 spicata. 
 
 RECAPITULATION. 
 
 108. What is inflorescence? Of what importance is it? 
 Explain the terms peduncle and pedicle. How is a peduncle 
 distinguished from all other axes of growth? What are 
 bracts? 109. What is a radical peduncle? Define the 
 scape. When a peduncle springs from the stem or branch, 
 how is it named ? Mention some other terms expressive of 
 the position and of the relations of the peduncle. 110. 
 What is a bractea ? What is a floral leaf ? How are bracts 
 described ? 111. What are the modifications of the bracts ? 
 Give an account of the involucrum and of the involucellum. 
 What is the cupule of the oak, of the hazel, of the beech ? 
 Describe the spatha. 112. In what respects are the bracteaj 
 of grasses remarkable ? Give a general description of them. 
 113. What is meant by a whorl ? Is the inflorescence of the 
 Labiatse a whorl? How is it correctly described? 114. 
 Define a spike, and give examples of this kind of inflorescence. 
 In what respect does the raceme differ from the spike ? 
 What other forms of inflorescence seem to be modifications 
 of the spike ? Describe the capitulum, the corymb, the cat- 
 kin, the spadix, the anthodium, and the sertule. 115. 
 Describe the umbel and the umbellule. What is a panicle ?
 
 ORGANS OP REPRODUCTION. 79 
 
 How does the thyrsus differ from the panicle ? What is a 
 cyme ? What is a fascicle ? 116. In what kinds of inflor- 
 escence are the lower or outer flowers first expanded ? 
 Describe the dichotomous mode of inflorescence. 117. To 
 what two classes may all the varieties of inflorescence be 
 reduced ? Explain the mode of definite inflorescence. What 
 is meant by centrifugal evolution? 118. Explain the mode 
 of indefinite inflorescence. What is meant by centripetal 
 evolution? 119. To which mode of inflorescence does the 
 cyme belong? Explain the dichotomous cyme. What is a 
 scorpioidal cyme ? What other inflorescence is definite in 
 its development? 120. To which mode of inflorescence 
 belong the spike and the raceme ? Explain the several 
 modifications of the spike as they occur in the catkin, the 
 cone, the spadix, and the spikelet. What is a rachis ? 121. 
 In what respect does the raceme differ from the spike ? 
 Explain the several modifications of the raceme, as exempli- 
 fied in the corymb, the umbel, and the capitulum. 122. Of 
 what decompositions does the raceme admit ? Exemplify 
 this in the panicle and the thyrsus. 123. Give some instances 
 of combinations of inflorescence. Exemplify the difference 
 which occurs in the inflorescence with reference to male and 
 female flowers in the same plant. 124. Explain some inter- 
 mediate modes of inflorescence. 
 
 CHAPTER X. 
 
 GENERAL CONSIDERATIONS RESPECTING THE 
 ORGANS OF REPRODUCTION. 
 
 125. General Idea of the Flower. The Mower may 
 be defined that part of a plant which is especially sub- 
 servient to the production of seeds. It is an apparatus 
 composed of the organs of fructification properly so
 
 80 FORMS OF RECEPTACLES. 
 
 called, and of those by which they are surrounded and 
 protected. Considered with respect to structure, it is an 
 assemblage of several whorls or series of leaves, more or 
 less modified in their form and texture, and situated, iu 
 the form of a bud, at the extremity of the peduncle. In 
 the state in which it presents itself in the more perfect 
 dicotyledonous plants, it is composed of an outer whorl 
 of leaves, the Calyx ; an inner whorl of a more delicate 
 texture, the Corolla ; within this, the Stamens ; and in 
 the centre, the Pistil or Ovary, inclosing the Seeds. The 
 point of attachment of the flower is named the Receptacle 
 or Torus. 
 
 126. Receptacle of the Flower. The summit of the 
 peduncle generally expands in some degree, forming a 
 kind of disk, from which the different parts of the flower 
 arise. This expansion has sometimes the form of a 
 fleshy protuberance, sometimes that of a mere plate, 
 scarcely distinguishable, from which the corolla and sta- 
 mens arise. This plate may be developed so as to be in 
 some measure prolonged over the outer and inner parts 
 of the flower, and sometimes it becomes thickened into a 
 kind of disk. It may also happen that the peduncle is 
 prolonged in the centre of the different parts of the flower, 
 so as to form an axis around which they are symmetri- 
 cally placed. Most commonly the flower terminates the 
 peduncle. 
 
 127. Forms of Receptacles. It is necessary to take a 
 more extended view of this portion of the inflorescence, 
 as it frequently presents an expansion of the summit of 
 the axis, upon which a large number of flowers is placed. 
 This expanded portion increases in size, in thickness, and 
 in fleshiness, according to the number of flowers which it 
 has to support, and to the nearer approach of the flowers 
 to the sessile state. The receptacle has been termed the 
 pJioranthium and clinanthium terms expressive of its
 
 FLOWER-BUDS. 81 
 
 office of supporting flowers. In di- and tri-chotomous 
 inflorescences, the expansion is scarcely perceptible ; in 
 umbelliferous plants, a small quantity of nutritive matter 
 is deposited in tbis part ; in composite plants, a very 
 large quantity is stored up in tbe receptacle, and affords 
 food for insects, and even for man, as in the artichoke. 
 After the flowering season the receptacle dries up, and 
 facilitates the expulsion of the fruits. 
 
 128. The Forms of the receptacle are numerous. It 
 is cylindrical or conical in eryngo and teazle ; convex in 
 many composite plants ; plane or slightly concave in 
 dorstenia ; curved inward at its margins, in some species 
 of this genus ; in the fig it is hollow, enclosing the 
 flowers and the fruit ; when perfectly ripe, this curious 
 receptacle opens spontaneously at its upper extremity. 
 Receptacles generally change Uieir form at the period of 
 maturity : the plane or convex bulge towards their centre; 
 the concave open by reflexion of their borders, for the 
 purpose of discharging their fruits. In the common arti- 
 choke, cultivated for culinary purposes, the parts eaten 
 are the fleshy bases of the bracts or scales of the invo- 
 lucrum, and the enlarged common receptacle, or the 
 "seat," as it is popularly called. The eatable part of 
 the bread-fruit (Artocarpus incisa) was described by 
 Dampier, as being " as big as a penny loaf, when wheat 
 is at 5s. the bushel, and all of a pure substance, like 
 bread. " The fruit of the jack or jaca tree (A. integrifolia) 
 sometimes weighs upwards of thirty pounds, but is less 
 esteemed as food. The juicy part of the raspberry con- 
 sists of minute fruits arranged around an unpalatable 
 spongy receptacle. In the strawberry, the receptacle 
 itself forms the eatable part ; in the former, the fruits 
 rob the receptacle of their nutriment ; in the latter, the 
 receptacle robs the fruits, which are minute dry acini. 
 
 129. Flower-Buds. Previously to entering upon the
 
 82 .ESTIVATION. 
 
 consideration of the parts of the flower, it is necessary 
 to advert to the bud of which it is the expansion. A 
 careful and comparative examination of the various parts 
 of which the flower is composed, and of the ordinary and 
 accidental changes which they undergo, shows, as Pro- 
 fessor Henslow remarks, that these organs are "modifi- 
 cations of a common germ, which may be developed 
 according to circumstances, either in the form of a 
 flower-bud, or of a leaf-bud, adapted in the one case to 
 perform the functions of reproduction, and in the other 
 those of nutrition. Flower-buds ought consequently to 
 make their appearance on similar parts of the stem and 
 branches with the leaf-buds, that is, in the axils of the 
 leaves ; and the development of such will present us with 
 analogous phenomena. However different in their ex- 
 ternal characters, still the various parts of the inflores- 
 cence must bear a strong affinity to those of the leafy 
 appendages on the branch." 
 
 130. ^Estivation. As the manner in which the leaves 
 are disposed within the bud is technically named the 
 vernation, p. 63, so that in which the parts of the flower 
 are arranged previous to its expansion, is named the 
 ^Estivation or Pratfloratwn. The principal modes in 
 which the corolla, or its parts, the petals, are disposed in 
 the bud, are the following : 
 
 1. The petals, or divisions of the corolla, may cover 
 each other laterally by a small portion of their breadth; 
 as in Rosa and Pyrus. In this case they are said to be 
 imbricated. ^Estivatio imhricativa. 
 
 2. A corolla consisting of one piece may be folded 
 upon itself, or plaited. ^E. plicativa; as in Convolvulus. 
 
 3. The petals, or the divisions of the corolla, may be 
 spirally twisted. ^E. torsiva; as in Oocalis. 
 
 4. The petals may be puckered, or wrinkled. JE. cor- 
 rugativa; as in the Poppy.
 
 PARTS OF THE FLOWER. 83 
 
 5. They may be placed so as to have their edges in 
 contact, like the valves or pieces of some seed-vessels. 
 JE. valvaris. 
 
 6. When there are five petals, two outer, two inner, 
 and one covering the latter by one of its sides, the Esti- 
 vation is said to be quincuncial. JE. quincuncialis; as 
 in Dianthus. 
 
 The calyx also may present all the above circumstances, 
 and the stamens may be erect, or bent inwards. 
 
 131. Parts of the Mower. A flower, such as we may 
 suppose complete, or possessed of all the parts that may 
 enter into its composition, is externally formed of two 
 whorls of leaves, constituting what is named the floral 
 envelope, or Perianth, and internally of two other whorls 
 of organs, which, if not resembling leaves in their form, 
 are yet analogous to them, and constitute the essential 
 parts of the flower, or the Organs of Fructification. 
 
 1. The outer whorl or envelope, is formed of several 
 pieces named Sepals, which are either free, that is, dis- 
 united, or in some degree coherent by their margins. 
 Collectively, they bear the name of Calyx or Flower-cup. 
 They have much of the aspect and structure of leaves, 
 and are generally green. 
 
 2. The next whorl, or second envelope, is formed of 
 several pieces named Petals, which are also either free, 
 or united, and are collectively named the Corolla. They 
 are generally highly coloured, and of more delicate tex- 
 ture than the sepals, which, however, they often resemble, 
 and into which they are sometimes transformed. 
 
 3. The third whorl is composed of the Stamens, which 
 are free or united, and usually composed of two parts: 
 an upper essential part, the Anther, a membranous bag, 
 in which the Pollen or fecundating powder, is contained; 
 and the Filament or stalk. The latter is sometimes folia- 
 ceous, and the anther itself is seen to be converted into
 
 84 RECAPITULATION. 
 
 a petal in the case of what is called a full flower, pro- 
 duced by cultivation. 
 
 4. The fourth whorl, which is placed in the centre of 
 the flower, is composed of pieces named Carpels, collec- 
 tively called the Pistil. These pieces are sometimes free, 
 generally united. A carpel is composed of three parts: 
 a lower, usually of a roundish form, named the Ovary, 
 which contains the ovules or young seeds; an upper, 
 named the Stigma, which receives the pollen at the 
 period of fecundation; and an intermediate part, named 
 the Style, which, however, is sometimes wanting. The 
 ovary is usually sessile, but is sometimes elevated on a 
 stalk, analogous to the petiole of a leaf. Each carpel 
 may be considered as a leaf folded inwards upon itself, 
 and having its tip prolonged into a style. 
 
 It thus appears, that, whether the calyx, corolla, sta- 
 mens and pistils, are to be considered simply as modified 
 leaves, or as distinct parts, they yet have a very decided 
 analogy to these organs; and the general idea of a uni- 
 formity of plan, merely presenting modifications accord- 
 ing to circumstances, is useful in enabling the student 
 more readily to apprehend and remember the series of 
 organs. 
 
 RECAPITULATION. 
 
 125. What is the Flower considered as to function and 
 structure ? What parts enter into its composition ? To what 
 is it attached ? 126. What is the Receptacle of the flower ? 
 Does it vary in form ? 127. What terms have been applied 
 to the receptacle ? In which plants is the receptacle spar- 
 ingly, in which largely developed? 128. Describe the 
 various forms of the receptacle, particularly as it occurs in 
 the fig. Explain the nature of the receptacle in the arti- 
 choke, the strawberry, and the raspberry. 129. Is there a 
 direct analogy between Mower-buds and Leaf-buds ? 130.
 
 THE CALYX. 
 
 What is meant by Estivation? Describe some of its 
 varieties. 131. What is the Perianth? What are the 
 Organs of Fructification? Give an account of the four 
 whorls of which a flower is composed. 
 
 CHAPTER XI.' 
 THE CALYX. 
 
 132. General Idea of the Calyx. The Perianth, or 
 floral envelope of the stamens and pistils, which are the 
 only essential parts of the flower, may be entirely want- 
 ing. When present, it may be single or double. In the 
 latter case it is composed of two whorls of leaves, which 
 may be distinct, or in various degrees united by the 
 edges. Should the two whorls themselves be united, 
 the perianth may assume the appearance of a Calyx, or 
 that of a Corolla, and thus it might be difficult to say 
 whether it ought to be considered as a united calyx and 
 corolla, or as either of these parts. Many writers say, 
 that when the perianth is single, as in the Tulip and 
 Lily, it ought to be considered as a calyx; others in such 
 a case call it a calyx when thick, and more or less green, 
 and a corolla when of delicate texture and highly coloured. 
 In many cases, as in Nymphcea, the calyx and corolla 
 pass so gradually into each other, that a distinction of 
 the parts can hardly be made. Professor Lindley thinks 
 the only just mode of distinguishing the calyx is to con- 
 sider it in all cases the most exterior verticillate series of 
 the flower, within the bracteae, of whatever texture or 
 colour it may be. A calyx therefore, he adds, can exist 
 without a corolla; but a corolla cannot exist without a 
 calyx. We may thus define the calyx the outermost
 
 86 MONOSEPALOUS CALTX. 
 
 integument of the flower, consisting of two or more ver- 
 ticillate leaves, either distinct or united, usually green, 
 and of a coarser texture than the corolla. 
 
 133. Composition of the Calyx. The leaves of which 
 the calyx is composed frequently cohere by their edges. 
 As these leaves are named Sepals, such a calyx, consist- 
 ing of a single piece, is named monosepalous, PI. X., 
 Fig. 126. For this term, however, M. Decandolle sub- 
 stitutes gamosepalous, implying that the calyx is com- 
 posed of several united sepals, and not of one sepal only. 
 It is polysepalous, when its leaves or sepals are distinct 
 and separate, as in the Wall-flower, or in Butomus um- 
 bettatus, PL XII., Fig. 128. According to the number 
 of the sepals, we may have a di-, tri-, tetra-, or penta- 
 sepalous calyx, denoting respectively the presence of two, 
 three, four, or five sepals. Sometimes the calyx is 
 united to, or covers, the ovary, in which case it is mono- 
 sepalous and superior. The monosepalous calyx is gene- 
 rally persistent, that is, remains until the fruit is ripe. 
 The polysepalous calyx is usually caducous, or falls off 
 after the flower expands. 
 
 134. Monosepalous Calyx. The cohering portion of 
 the sepals constitutes the tube of the Calyx; the non- 
 cohering, or upper portion, constitutes the limb; the 
 part at which the tube and the limb unite, is called the 
 faux or throat. The limb consists of divisions which, 
 when large, are called lobes; when short and narrow, 
 teeth. Sometimes the sepals cohere unequally, so as to 
 leave a large space between certain lobes; a calyx is then 
 said to have lips: two sepals may cohere, and form an 
 ujyper lip, while three cohere to form a lower lip; the 
 calyx is then termed two-lipped, PI. XIII., Fig. 161, or 
 all the sepals may cohere together to one side, consti- 
 tuting a one-lipped calyx. 
 
 135. The sepals having the characters of leaves, are
 
 THE PAPPUS. 87 
 
 described by the terms applicable to these organs. Thus, 
 with reference to their perfect or partial union, the mono- 
 sepalous calyx is said to be entire, toothed, deft, partite, 
 &c. 1. With regard to form, the calyx is tubular in 
 Primrose, PI. XL, Fig. 142, urceolate, or pitcher-shaped 
 in Rose, PI. IX., Fig. 123, inflated in Bladder Cam- 
 pion; campanulate, or bell-shaped in Campanula; cup- 
 shaped, or concave in Eucalyptus, PI. X., Fig. 136, 
 calcarate, spurred, or having a prolongation at the base, as 
 in Trophy-cress, commonly called Nasturtium, PI. XIII., 
 Fig. 170. 
 
 136. In exogenous plants there are usually five sepals, 
 or, in cases of cohesion, five lobes; occasionally, there 
 are only three; more rarely, two, four, six, &c. In 
 endogenous plants, there are commonly three sepals. 
 
 137. The Pappus. A very curious modification of 
 the Calyx is that to which the name of Pappus is given, 
 PI. XVI., Fig. 204. It is peculiar to plants belonging 
 to the natural family of the Composite, and is familiarly 
 exemplified in the Thistle, it being the part which crowns 
 the pericarps of that plant, and hy the aid of which they 
 are conveyed to a distance by the winds. In these plants 
 the ovary is placed below the corolla, and from its sum- 
 mit arises a crown of bristles or scales, which are analo- 
 gous to the calyx, PL XVI., Fig. 210. This kind of 
 calyx is persistent, remaining until the fruit is matured. 
 It presents several modifications. Thus, it may be ses- 
 sile, or proceeding directly from the summit of the ovary, 
 without the intervention of any other body ; or it may be 
 supported upon a small stalk, when it is said to be stipi- 
 tate. The filaments or hairs of which it is composed 
 may be simple, in which case the pappus is said to be 
 pilose; or they may have on their sides smaller filaments, 
 resembling, in some measure, those of a feather, when 
 the pappus is called plumose or feathery.
 
 RECAPITULATION. 
 
 138. General Remarks. In most cases the calyx is 
 green, and resembles the leaves in texture. Frequently, 
 however, it is of some other colour; and when the corolla 
 is wanting, or the perianth single, it often assumes the 
 most beautiful tints. In this case it is said to be peta- 
 loid or corottiform. Although generally shorter than the 
 corolla, it sometimes equals or exceeds it in length. It 
 may be free, or, on the other hand, in some degree adhe- 
 rent to the ovary. Its venation is that of the leaves, 
 frequently penninerved. The central vein is termed 
 primary or carinal; the vein which results from the co- 
 hesion of two adjacent sepals, is called autural. 
 
 RECAPITULATION. 
 
 132. What is meant by the Perianth ? Is it ever wanting ? 
 Is it always, when present, double ? When single, how can 
 it be determined whether it is a calyx or corolla? Define the 
 Calyx. 133. What are the leaves of the calyx named ? When 
 the sepals are united, what term is applied to the calyx? 
 What is a polysepalous calyx ? What is meant by persistent 
 and caducous ? 134. What are the tube, the limb, and the 
 throat of the calyx ? What is meant by a two-lipped, by a 
 one-lipped calyx? 135. Explain the terms urceolate, cam- 
 panulate, and calcarate, as applied to the calyx. 136. What 
 
 DESCRIPTION OF PLATE XIII. Corolla. Fig. 159. Cam- 
 panulate or Bell-shaped Corolla. Tig. 160. Infundibuliform 
 or Funnel-shaped Corolla. Fig. 161. Eingent, Gaping, or 
 Bilabiate. Fig. 162. Personate or masked. Fig. 163. Papi- 
 lionaceous. Fig. 164. Vexillum or Standard of the same. 
 Fig. 165. Ala or Wing. Fig. 166. Carina or Keel. Fig. 167. 
 Stamens and Style. Fig. 168. Incomplete Corolla of Rittera. 
 Fig. 169. Peloria or regular-flowered variety of Linaria vulgaris. 
 Fig. 170. Spur of the calyx of Tropteolum. Fig. 171. Horn- 
 like petal of Aquilegia. Figs. 172, 173. Nectary of Epimedmm.
 
 THE COROLLA. 89 
 
 is the usual number of sepals in exogenous and in endogenous 
 plants ? 137. Describe the Pappus. How many varieties 
 does it present? 138. Is the calyx always green? What 
 proportion does it bear to the corolla ? 
 
 CHAPTER XII. 
 THE COROLLA. 
 
 139. General Idea of the CoroUa. Within the calyx 
 is the CoroUa, a whorl of leaves, of more delicate tex- 
 ture, and generally more highly coloured. It imme- 
 diately surrounds the stamens, and is that part popularly 
 called the Flower. The leaves of which this whorl is 
 composed are named Petals. Like the sepals, or leaves 
 of the calyx, the petals are either free, or united by the 
 edges in various degrees. When they are united, the 
 corolla is said to be monopetalous or gamopetalous, PI. 
 XIII., Fig. 159 ; when free, \t\spolypetalous, PI. XIII., 
 Fig. 163. In many cases each petal exhibits two more 
 or less distinct parts; the Claw, Unguis, or lower, con- 
 
 DESCK.IPTION OF PLATE XII. Calyx and Corolla. Fig. 
 147. Spatha of Narcissus; a. the Sepals; b. the Crown. 
 Fig. 148. Two glumes or husks of a grass, with two flowers 
 within, each having an awn. Fig. 149. Awn or Arista of 
 the same. Fig. 150. Scaly sheath and capsule of Pterogonium 
 Smithii. Fig. 151. Calyptra or Veil of the same. Fig. 152. 
 Jungermannia epiphylla, showing the Veil and unopened Cap- 
 sule. Fig. 153. Volva or Radical Wrapper of an Agaricus. 
 Fig. 154. Volva. Fig. 155. Hypocrateriform or Salver-shaped 
 Corolla. Fig. 156. Cruciform CoroUa. Fig. 157. A Petal 
 of the same. Fig. 158. Unequal Corolla of Butonms.
 
 90 MONOPETALOUS COROLLA. 
 
 traded part by which it is attached to the receptacle ; 
 and the Lamina, or Limb, which is the expanded part, 
 PI. XII., Fig. 157. The unguis is thus analogous to the 
 petiole, and the lamina to the blade of the leaf. The 
 petals vary exceedingly in figure, being roundish, ovate, 
 lanceolate, obtuse, acute, entire, emarginate, <fcc., the same 
 terms being applied to them as to the leaves. When the 
 petals, whether free or united, are equal to each other, 
 the corolla is said to be regular, PI. XII., Fig. 155, 156. 
 When the reverse is the case, that is, when the petals are 
 not equal, or when they adhere so as not to have a sym- 
 metrical form, it is irregular, PI. XIII., Fig. 161, 163. 
 
 140. Monopetalous Corolla. In a corolla of which the 
 petals are united, three parts are distinguished: 1, a 
 lower, narrow, more or less tubular and elongated part, 
 named the Tube. Tabus; 2, a part continuous with the tube, 
 more or less dilated, often spreading out flat, or even re- 
 curved, and named the Limb, Limbus; 3, the circular 
 line at which the tube and limb unite, or the Throat, 
 Faux. The tube is formed by the united claws, the limb 
 by the laminae of the petals. A monopetalous corolla 
 may be regular or irregular. 
 
 141. Regular Monopetalous Corolla. The semblance 
 of various familiar objects is assumed by the monopeta- 
 lous corolla in its modifications. Thus it may be, 
 
 1. BeU-shaped or Campanulate. Corolla Campanulate. 
 When it resembles a bell, the tube being inconspicuous, 
 the limb bulging out and gradually widening, with the 
 mouth spreading; as in Campanula, PI. XIII, Fig. 159. 
 
 2. Funnel-shaped. C. infundibuliformis. When the 
 tube is narrow, but gradually dilates, and the limb pre- 
 serves nearly the same direction; as in Nicotiana. PI. 
 X1IL, Fig. 160. 
 
 3. Tubular. C. tubulata. When narrow and elon- 
 gated. PI. XVII., Fig. 212.
 
 IRREGULAR MONOPETALOUS COROLLA. 91 
 
 4. Salver-shaped. C. hypocrateriformis. When the 
 tube is long, narrow, and nearly of equal diameter through- 
 out, while the liinb spreads out flat; as in the Primrose. 
 PI. XII., Fig. 155. 
 
 5. Eotate or Whed-shaped. C. rotata. When the 
 limb is spreading, and the tube very short; as in Borago. 
 
 6. Pitcher-shaped. C. urceolaJLa. When globular or 
 egg-shaped, and contracted at the mouth; as in Vacci- 
 nium. 
 
 142. Irregular Monopetalous Corolla. The following 
 are the principal varieties of this kind of corolla: 
 
 1. Ringent or Lipped. C. ringens, labiata. When 
 the tube is narrow, the throat more or less dilated, and 
 the limb divided into two unequal parts, one of which is 
 named the upper, the other the lower lip. This kind of 
 Corolla is seen in Rosemary, Thyme, the Deadnettle, and 
 other plants of the natural family of Labiatce. PI. X., 
 Fig. 126. PI. XIII., Fig. 161. 
 
 2. Masked or Personate. C. personata. When the 
 tube is more or less elongated, the throat wide, but closed 
 by the approximation of the opposite sides of the limb, 
 which is divided into two lips; as in Antirrhinum. PI. 
 XII., Fig. 162. 
 
 3. Spurred. C. calcarata. When the corolla has at 
 its base a hollow prolongation like a horn; as in the 
 tigure last referred to. 
 
 4. Strap-shaped. C. ligulata. When tubular at the 
 base, then slit on one side, so that the limb becomes flat; 
 as in the Dandelion. PI. XVI., Fig. 210, 211. 
 
 143. Terms applied to the Parts. The various parts 
 of the monopetalous corolla present numerous modifica- 
 tions, which require to be attended to. Thus: 
 
 1. The Tube may be cylindrical, as in the Lilac; long, 
 as in the Primrose; short, as in the Bell-flower; inflated 
 or bulging; smooth, striated, angular, &c.
 
 92 POLYPETALOUS COROLLA. 
 
 2. The Throat may be open, as in Digitalis; closed, as 
 in Snap-dragon; crowned with projecting teeth or appen- 
 dages of various forms, as in Borage and Comfrey; hairy, 
 as in Thyme; naked, or without hairs. 
 
 3. The Limb may be erect, as in Hound's-tongue; 
 sheading, as in the Primrose; reflexed, or bent outward, 
 as in Solanum; toothed on the margin, or according to the 
 number and depth of its divisions, trifid, quadrifid, quin- 
 quefid, tripartite, quadripartite, quinquepartite. The 
 divisions of the limb are described in the same manner 
 as leaves. 
 
 144. Polypetalous Corolla. When a corolla is com- 
 posed of two petals, it is termed dipetalous; when of 
 three, tripetalous ; offom',tetrapetalous, PI. XII., Fig. 156 ; 
 of five, pentapetalous, PI. XIV., Fig. 175; of six, heoca- 
 petalous. The petals may be sessile, or unguiculate; 
 and the length of the unguis may be shorter or longer 
 than the calyx. They may be 
 
 1. Erect. Petala erecta. In the direction of the 
 axis of the flower; as in Geum rivale. 
 
 2. Spreading. P. patentia. When they are nearly 
 at right angles to the axis of the flower; as in Rosa, 
 
 3. Eefleded. P. reflexa. When bent or curved out- 
 wards and downwards. 
 
 4. Inflected. P. inflexa. Curved toward the centre 
 of the flower. 
 
 The petals vary exceedingly as to form in different 
 plants, and are described in the same manner as the 
 sepals and leaves, being roundish, ovate, obovate, obcor- 
 date, elliptical, lanceolate, incised, lobed, smooth, <fcc. 
 Sometimes they present very singular forms. Thus, 
 they are 
 
 Helmet-shaped or Galeated. P. galeiformia. When 
 vaulted, hollow, and somewhat resembling a helmet ; as 
 in Monk's-hood, Aconitum Napellus.
 
 POLYPETALOTJS COROLLA. 93 
 
 Coid-shaped or cucuttiform. P. cucuUiformia. Hav- 
 ing the form of a cowl or hood; as in Columbine arid 
 Larkspur. 
 
 Considered individually, a petal, as already stated, ge- 
 nerally presents two distinct parts, the Unguis or Claw, 
 and the Lamina or Scale, PI. XII, Fig. 157. The claw 
 is the narrow part at the base, by which the petal is at- 
 tached to the receptacle, the lamina being the expanded 
 part. The claw may be so short as to be scarcely dis- 
 tinguishable, or elongated so as to exceed the calyx. 
 
 As the monopetalous corolla maybe regular or irregu- 
 lar, so also the polypetalous. 
 
 145. Regular Polypetalous Corolla. Three principal 
 modifications of this kind of Corolla are described. 
 
 1. The Cruciform. C. crucifonnis. When four petals, 
 having elongated claws, are placed in pairs, opposite to 
 each other, in the manner of a cross ; as in Wall-flower, 
 Cabbage, and W T ater-cress, PI. XII. , Fig. 156. 
 
 2. CaryophyUaceous. C. caryophyUacea. When there 
 are five petals, of which the claws are very long, and 
 covered by the calyx, which is also very long and erect ; 
 as in the Pink and Catchfly, PI. XI., Fig. 142. 
 
 3. Rosaceous. C. rosacea. When there are five round- 
 ish, spreading petals, of which the claws are very short; 
 as in the Rose, Apple, Cherry, and Ranunculus, PI. 
 XIV., Fig. 175. The number of petals may vary, how- 
 ever, from three to six. 
 
 146. Irregular Polypetalous Corolla. When the petals 
 are unequal, the corolla is said to be irregular. This 
 often happens in the Cruciform corolla above described, 
 two of the petals being larger than the rest. Among 
 the most remarkable corollas of this kind are the fol- 
 lowing: 
 
 1. The Papilionaceous. C. papilionacea. PL XIII., 
 Fig. 163. It is so named on account of its fancied
 
 94 POSITION OF THE PETALS. 
 
 resemblance to a butterfly, and is composed of five petals, 
 distinguished by appropriate names. The large petal at 
 the back, Fig. 164, is named the standard, vexUlum ; 
 the two lateral petals, which are equal, Fig. 165, the 
 wings, alee; and the two inferior petals, Fig. 166, also 
 equal, and often united, by their lower margin, into a 
 concave blade, named, from its appearance, the Jced, 
 carina. This kind of corolla is that seen in the great 
 natural family of Leguminosse, such as the Pea, the 
 Bean, and Vetch. Sometimes, however, the petals of the 
 papilionaceous corolla are united at the base, where they 
 form a tube ; as in Clover. 
 
 2. Anomalous. C. anomala. Consisting of five irre- 
 gular petals, and somewhat resembling the papilionaceous 
 corolla ; as in the Violet. 
 
 3. Incomplete. C. incompleta. When petals, which 
 analogy would lead us to expect, are wanting ; as in 
 Riitera, PI. XIII., Fig. 168, a rosaceous corolla, having 
 only a single petal. 
 
 147. Position of the Petals. Considered with refer- 
 ence to the sepals, the sepals may be placed as follows: 
 
 1. They may be opposite to the sepals, that is, the 
 outer surface of the petal may be placed opposite to the 
 inner surface of the sepal, so that the petals and sepals 
 may correspond in position ; as in the Barberry. 
 
 2. They may be alternate, that is, the petal may be 
 placed, not opposite to the sepal, but opposite to the 
 space between two sepals ; as in the Wall-flower. 
 
 These circumstances refer not only to the polypetalous, 
 but also to the monopetalous calyx and corolla. 
 
 The petals, whether united or free, may be placed 
 upon the receptacle, immediately -within or above the 
 sepals, as in the Primrose and Ranunculus; or they may 
 be attached to the margin of the tube of the calyx, at a 
 distance from the receptacle, as in the Rose and Straw-
 
 RECAPITULATION. 95 
 
 berry ; or they may come off from the summit of the 
 ovarium, as in the Thistle and Valerian. 
 
 148. Other circumstances of the Corolla. The corolla, 
 although generally longer than the calyx, may be shorter, 
 and the relative proportions of the sepals and petals 
 afford good distinctive characters. When the corolla 
 falls off as soon as it expands, it is said to be fugacious, 
 C. fugax; when it falls after the bursting of the anthers, 
 it is deciduous, C. decidua; when it remains after fecun- 
 dation, in a withered state, it is marcescent, C. marcescens. 
 The colours exhibited by the corolla are of almost every 
 possible variety of tint, excepting black, and depend upon 
 the coloured fluids, or granules, in the cells of its tissue. 
 The odours emitted by it are also extremely varied, 
 although less capable of being defined. The petals are 
 composed of cellular tissue, in which are distributed 
 vascular fasciculi, and are covered on both surfaces with 
 a delicate epidermis. 
 
 RECAPITULATION. 
 
 139. What is placed immediately within the calyx ? What 
 name is given to the leaves of the corolla ? When the petals 
 are united, what is it said to be ? What is a polypetalous 
 corolla? 140. What parts are distinguished in the monope- 
 talous corolla? 141. What are the principal varieties, as to 
 shape, of the regular monopetalous corolla? 142. Define a 
 labiate corolla. Mention the varieties of the irregular mono- 
 petalous corolla. 143. Does the tube vary in form, and other 
 circumstances ? What modifications does the limb present ? 
 
 144. How is a corolla named with reference to the number 
 of its petals ? What are the principal directions of the 
 petals ? How are they described ? What singular forms do 
 they present ? Into how many parts is a petal divided ? 
 
 145. What are the principal kinds of the regular polypetalous 
 corolla? 146. Describe the papilionaceous corolla. What
 
 96 THE STAMENS. 
 
 is meant by anomalous and incomplete ? 147. How are the 
 petals placed with reference to the sepals ? 148. What pro- 
 portion does the corolla bear to the calyx? What terms 
 referring to duration are applied to the corolla? Make a 
 general statement as to its colours and odours. Of what are 
 the petals composed ? 
 
 CHAPTER XIII. 
 THE STAMENS. 
 
 149. Nature of the Stamens. Within the corolla is a 
 whorl of modified leaves, which differ so much in form 
 from those organs, that their analogy could not at first 
 sight be suspected. Their function too is different, for 
 they are the organs by means of which the rudimentary 
 ovula or seeds are impregnated. They are thus analo- 
 gous to the male organs of animals, while the central 
 part, or pistil, represents the female organ. The stamens 
 and pistils then are the sexual or reproductive organs of 
 plants. Generally they both exist in the same flower, 
 which is thus said to be hermaphrodite or perfect. 
 Sometimes, however, a flower has only stamens, when it 
 is said to be male or sterile; or it has only pistils, when 
 it is female ov fertile. When a male flower and a female 
 flower, or several flowers of each kind, are placed on the 
 same individual plant, the latter is said to be monoecious; 
 as the Hazel. When an individual plant bears flowers 
 with stamens only, and another individual of the same 
 species bears pistils only, the species is said to be dioe- 
 cious; as the plant named Dog's Mercury. When on 
 the same individual plant, or on different individuals of 
 the same species, are placed male flowers, female flowers, 
 and perfect flowers, the species is said to be polygamous;
 
 POSITION AND DIRECTION OF STAMENS. 97 
 
 as the Pellitorj. In PL XIV., Fig. 175, are seen the 
 tips of the five sepals, the five petals, the five stamens, 
 the pistil in the centre, and between the stamen scales 
 fringed with glandule-tipped filaments. 
 
 150. Number and Proportion of Stamens. The num- 
 ber of stamens varies in different plants from one to a 
 hundred or more. When a flower has only a single 
 stamen, it is said to be monandrous; when it has two 
 stamens, diandrous; when three, triandrous; when four, 
 tetrandrous; five, perdandrous; six, hexandrous; seven, 
 lieptandrous ; eight, odandrous; nine, enneandrous; ten, 
 decandrous, <fcc. When a flower contains more than ten, 
 but fewer than twenty, it is dodecandrous; and when a 
 great number, polyandrous. Very frequently the stamens 
 are equal in length, as in Parnassia, PI. XIV., Fig. 175; 
 but they are often unequal. When of four stamens, two 
 are equal, and longer than the other two, the stamens 
 are didynamous; as in the Dead Nettle and Thyme. 
 Six stamens, of which four are equal and longer than 
 the rest, are tetradynamous; as in the Wall-flower and 
 Turnip. In many other cases, some of the stamens are 
 longer than the rest, as in Geranium and Malva, but no 
 particular terms are applied to them. 
 
 151. Position and Direction of Stamens. Generally 
 the stamens, when equal in number to the petals, are 
 alternate with them; but sometimes they are opposite to 
 the petals. When the number of stamens is double that 
 of the petals, half of them are alternate, the other half 
 opposite to the divisions of the corolla. They may be 
 opposite to the sepals, as in most cases; or alternate. 
 With respect to their direction, stamens are said to be 
 erect, when parallel to the axis of the flower, as in Lilies ; 
 inflected, when curved toward the centre of the flower, 
 as in Lamium; reflected, when bent outwards, as in 
 Parietaria; spreading, when spread out at right angles
 
 98 FILAMENT AND ANTHER. 
 
 to the axis of the flower, as in Rosa; pendulous, when 
 so slender as to be unable to support themselves, as in 
 the Grasses; ascending, when directed toward the upper 
 part of the flower, as in Salvia; dedinate, when directed 
 toward the lower part of the flower, as in ^Esculus. 
 
 152. Parts of the Stamen. The stamen is essentially 
 composed of two parts; the Anther, Anthera, a membran- 
 ous, generally two-celled sac; and the PoUen, a substance 
 usually formed of numerous minute grains, containing 
 the fecundating matter. Very frequently, however, a 
 third part exists, namely the Filament, Filamentum, 
 varying in length, and elevating the anther. The fila- 
 ment is thus merely an accessory part of the stamen, 
 which is often sessile, being attached without the inter- 
 vention of that part. PI. XIV., Fig. 176, represents a 
 stamen, a, being the filament, and b, the double-celled 
 anther. 
 
 153. The Filament. The filament presents various 
 forms: it is usually filiform, or thread-like; but it may 
 be capillary, or hair-like, as in Grasses; subulate, or 
 awl-shaped, as in Tulip; clavate, or club-shaped; cunei- 
 form, or wedge-shaped; flattened or petaloid, expanded 
 
 and coloured like a petal. Filaments are usually sepa- 
 rate, but they may contract adhesion: when all the fila- 
 ments adhere together through a portion of their extent, 
 so as to form a tube, they are said to be monadelphous, 
 as in Mallow; when adhering in two sets, they are dia- 
 delphous, as in Fumitory; when in three or more parcels, 
 they are polyadelphous, as in St. John's Wort. 
 
 154. The Anther. The membranous sacs, constituting 
 the Anther, Anthera, are generally two, and placed in 
 contact with each other, but they are often more or less 
 separated by the intervention of a body named the Con- 
 nective. Although thus most commonly bUocular, the 
 anther is sometimes unilocular, being composed of a
 
 FORM OF THE ANTHER. 99 
 
 single cell; and more rarely quadrilocular. Each sac 
 or cell has generally on some part of its surface a longi- 
 tudinal groove, at which it opens. The surface on which 
 this groove is placed, is named its face, while the other 
 side is the back. Generally each cell has a longitu- 
 dinal septum opposite the slit. Frequently the cells of 
 the anther have little appendages, in the form of hristles 
 or crests. The connective varies in form and extent, 
 heing usually little apparent, but sometimes very large. 
 In the Sage it is forked, one division hearing a single- 
 celled anther, the other bearing a rudimentary or abor- 
 tive cell. In this case it is said to be distractUe. 
 
 155. Attachment and Direction of the Anther. 1. The 
 Anther may be attached by the middle of its length to 
 the extremity of the filament; it then presents, before 
 flowering, a vertical position, and afterwards a horizon- 
 tal one; this is the oscillating or versatile anther. Or it 
 may be inserted by one of its extremities to the top of 
 the filament, of which it then appears to be a continua- 
 tion; this is the erect anther. Or, it may be attached to 
 the filament by a considerable portion of its length, so as 
 to have no proper motion; this is the adnate anther. In 
 this case the filament is frequently prolonged above the 
 anther, in the form of an appendix, of a filiform, lamel- 
 lated, or glandular appearance. Some writers employ 
 the terms basifixed and medii/ixed, the former denoting 
 the attachment of the anther by its base to the top of the 
 filament, the latter, the attachment of the summit of the 
 filament to the middle of the back of the anther. 2. With 
 respect to their direction, anthers are said to be inlrorse, 
 when they face the axis of the flower; extrorse, when 
 their face is directed outward. 
 
 156. Form of the Anther. Anthers present a great 
 variety of forms. Thus, they may be spforoidal, globosce, 
 as in Mercurialis ; didymous, didymce, when of two
 
 100 . TEE POLLEN. 
 
 spheroidal lobes, as in Euphorbia ovoidal, ovoidce ; ob- 
 long, oblongce linear, lineares, very long and narrow ; 
 arrow-shaped, sagittatce; heart-shaped, cordiformes; kid- 
 ney-shaped, reniformes. They may be acute, acuminate, 
 bifid, bipartite; two-Jiorned, bicornes, as in Vaccinium 
 MyrtiUus; appendlculate, appendiculatce, having at their 
 summit appendages of various kinds. 
 
 157. Dehiscence of the Anther. Sometimes before the 
 flower is expanded, and sometimes afterwards, the cells 
 of the anther open, and allow the pollen or granules con- 
 tained in them to escape. This opening, or dehiscence, 
 most commonly takes place in the suture, or line of 
 separation of the two valves, in which case the cells are 
 said to be longitudinally dehiscent, Loculi longitudinaliter 
 dehiscentes ; as in the Tulip. Sometimes it takes place 
 by slits or pores, which may be placed at the summit, 
 L. apice dehiscentes, as in Heaths; or at the base, L. basi 
 dehiscentes, as in Pyrola. Sometimes also it takes place 
 by small valves; as in the Barberry. 
 
 158. Cohesion of Anthers. Generally, even when the 
 filaments are united or coherent, the anthers are free; 
 but sometimes the anthers unite so as to form a kind of 
 tube, surrounding the style. This is the case in the ex- 
 tensive family of plants, named, on this account, Synan- 
 therea, such as the Dandelion, Daisy, and Thistle. 
 
 159. The Pollen. The substance contained in the 
 cells of the anther, and which is subservient to the fecun- 
 dation of the ovules or rudimentary seeds, generally con- 
 gists of a multitude of grains, and is named the Pollen. 
 These grains vary much in form in various plants, being 
 in most cases spherical or elliptical, sometimes cylindri- 
 cal, square, triangular, flattened, or polyhedral. The 
 membrane which surrounds the granules is generally 
 smooth, sometimes bristly, or marked with prominences. 
 When smooth, it is dry, but when covered with asperi-
 
 INSERTION OF THE STAMEN. 101 
 
 ties, which are secreting organs, it has a clammy fluid 
 spread over it. Although commonly distinct from each 
 other, the grains sometimes cohere in clusters, or coalesce 
 in masses. They are coated with two membranes, of 
 which the inner is the more delicate. When immersed 
 in water, they assume a spherical form, the outer coat 
 bursts, and the inner projects at one or more points. 
 The cavity of the grains is filled with granules of extreme 
 minuteness, collectively named the fovitta, varying in 
 form, and having a rotatory motion of great rapidity. 
 
 160. Development and Dispersion of Pollen. At first 
 the pollen presents itself in the form of a cellular mass 
 filling the cavity of the cell of the anther, but having no 
 attachment to its walls. By degrees the grains separate, 
 enlarge, and assume their permanent form. When the 
 cells of the anther open, the grains of pollen are gene- 
 rally discharged at once ; but sometimes, when the dis- 
 charge takes place by pores or holes, the grains are 
 gradually emitted, and in greater quantity than would 
 fill the cells, so that they must be successively secreted, 
 or at least enlarged. Some of the grains of pollen fall- 
 ing on the stigma, which is generally covered with a 
 clammy fluid, emit a process, Avhich, gradually elongat- 
 ing, makes its way into the cellular tissue of the style. 
 The ovules then enlarge, and are gradually perfected. 
 
 161. Insertion of the Stamens. Three varieties of 
 position Avith reference to the ovary are distinguishable, 
 and considered of great importance in the arrangement 
 of plants. 
 
 1. Hypogynous Insertion. When the stamens, whether 
 their filaments be free, or adherent to a monopetalous 
 corolla, are attached or inserted beneath the ovary, 
 they are said to be hypogynous; as in the Poppy and 
 Hyacinth. 
 
 2. Perigynous Insertion. When the stamens are in-
 
 102 RECAPITULATION. 
 
 serted upon the inner surface of the calyx, at some dis- 
 tance from the axis of the flower, they are perigynous; 
 as in the Rose and Strawberry. 
 
 3. Epigynous Insertion. When the stamens, whether 
 their filaments be free, or attached to a monopetalous 
 corolla, are inserted upon the summit of the ovary, they 
 are epigynous; as in Hemlock and Campanula. 
 
 In reality, however, the stamens always originate from 
 the space between the base of the petals and the base of 
 the ovary; the apparent differences of insertion being 
 produced by differences in the adhesion of the ovary and 
 floral envelopes. 
 
 Sometimes the filaments are attached to the style, the 
 male and female organs being thus in a manner united. 
 In this case the flower is said to be gynandrous, as in 
 Passion-flower. 
 
 162. General Remarks. The filament consists of a 
 bundle of woody fibre and spiral vessels, enveloped in 
 cellular tissue, and is analogous to the petiole of the leaf. 
 Although generally white, it is sometimes red, blue, or 
 yellow. The anther, which is very frequently yellow, 
 but also of other colours, is considered to be analogous 
 to the lamina or expanded part of the leaf. Indeed, the 
 gradual change of the petals, which are evidently modi- 
 fied leaves, into the stamens, is obvious in Nymphcea, 
 and many other plants. In the stamen, however, there 
 is a part, the fovilla, or mass of pollen, which has nothing 
 analogous to it in the petals, sepals, or leaves. Judging 
 from what takes place in Nympluxa, it would be better 
 to consider the filament as representing the leaf, and the 
 two cells of the anther to have no analogue. 
 
 RECAPITULATION. 
 
 149. What whorl is placed within that of the petals ? 
 What is the function of the stamens ? To what are the sra-
 
 THE PISTIL. 103 
 
 nieus and pistils analogous ? Do they often exist together on 
 the same flower ? What is meant by perfect, sterile, and fer- 
 tile flowers ? What are monoecious, dioecious, and polyga- 
 mous flowers ? 150. What terms are applied to the flowers 
 with reference to the number of their stamens ? How are 
 stamens named with reference to their relative length ? 151. 
 How are the stamens placed relatively to the divisions of the 
 corolla ? What are their principal directions ? 152. Of what 
 parts is the stamen composed ? 153. Mention some of the 
 forms assumed by the filament. When the filaments are con- 
 nected, so as to form one, two, or more parcels, how are they 
 named ? 154. Of how many sacs or cells is the anther 
 formed ? What is the connective ? Does it vary in form ? 
 155. How is the anther named with reference to its mode of 
 attachment ? When is an anther said to be introrse or ex- 
 trorse ? 156. Does the anther vary in form ? 157. How does 
 its dehiscence take place ? 158. Do the anthers ever cohere ? 
 159. Give a general account of the pollen. 160. How is it 
 developed and dispersed ? 161. What is meant by hypogy- 
 nous, perigynous, and epigynous, insertion of the stamens ? 
 162. Is the analogy between stamens and leaves very ob- 
 vious ? 
 
 CHAPTER XIV. 
 THE PISTIL. 
 
 163. Nature of tJie Pistil. The central orgau of the 
 flower ia composed essentially of a Germen or Ovarium, 
 containing the young Seeds or Ovules, and of a Stigma, 
 or fleshy extremity, which may either be seated directly 
 upon the ovarium, or elevated upon a stalk, named the 
 style. These parts collectively constitute the Pistil, Pis- 
 tillum, of which Fig. 177, PI. XIV., represents the 
 pistil, a; the style, b; the stigtna, c. The pistil may
 
 104 ARRANGEMENT OP CARPELS. 
 
 be simple or compound : in the former case, it is formed 
 of a single leaf named the Carpd, Carpettum; in the lat- 
 ter, of several carpels. Each carpel is an organ analo- 
 gous to a leaf, folded inwards upon its midrib, so that its 
 two edges, coming into contact, cohere, forming the 
 placenta, to which the ovules or young seeds are 
 attached. 
 
 164. TJie Ovarium. Considering the single pistil, 
 then, as a leaf folded inwards upon itself in the direction 
 of the axis of the plant, we find that the ovarium or ger- 
 men is the lamina, the style an elongation of the midrib, 
 and the stigma the humid secreting apex of the latter. 
 This appears obvious from the examination of what takes 
 place in the double cherry-flower, in which the pistil is 
 altered so as to assume the appearance of one of the 
 common leaves of the tree, having the two sides of its 
 upper or inner surface brought together, its margins in 
 contact, its midrib prolonged, and its tip somewhat en- 
 larged and discoloured. For the most part, the carpel 
 is sessile, but in some cases it is elevated upon a stalk, 
 named the thecaphore, which is thus analogous to the 
 petiole of the leaf. When the pistil is composed of 
 several leaves or carpels, it is said to be compound or 
 multiple. In this case the carpels are usually arranged 
 so as to form a single whorl, but sometimes so as to pre- 
 sent several whorls placed within each other. 
 
 165. Arrangement of Carpels. A pistil composed of 
 a whorl or whorls of carpels, may present the following 
 arrangements: 1. The carpels are whorled round a real 
 axis, formed by a prolongation of the pedicle; to this 
 they adhere by their inner angle, as in Mallow and 
 Spurge. 2. They are whorled round a central column, 
 to which they are suspended, being attached merely by 
 the summit of their inner angle, as in Geranium. 
 3. They are ivhorled round the summit of the axis, but
 
 DISSEPIMENTS OF THE OVARY. 105 
 
 are erect, and adhere by the base of the inner angle, as 
 in Aconite, in which the axis is so short as to be imper- 
 ceptible. But the axis is elongated, and the whorl raised 
 in Rue. 4. They are disposed in a spike around the 
 central axis in Ranunculus and Magnolia. The axis may 
 be very short or rounded, and the carpels collected into 
 a compact head, as in Blackberry and Raspberry. 
 5. They are scattered upon the walls of the torus adher- 
 ing to the calyx, as in Rose the only case, perhaps of 
 this kind of arrangement. In all these cases, several 
 carpels are supposed to exist, and this is the normal 
 state ; by abortion, however, or cohesion, they may be 
 reduced to unity, really or apparently. 
 
 166. Form and Relations of the Ovary. Although 
 generally ovoidal or roundish, the ovariuni assumes a 
 variety of forms, being trigonal, tetragonal, pentagonal, 
 lobed, depressed, or more or less elongated and compressed. 
 It is generally free, or not adherent to the calyx, as in 
 the Hyacinth and Tulip; but sometimes it is united 
 with the tube of the calyx, so that its summit alone is 
 free, as in the Apple and Hawthorn. In the former 
 case it is said to be superior, with relation to the peri- 
 anth; in the latter, inferior. Sometimes the ovary is ad- 
 herent in part of its extent, and free in the upper part; 
 as is seen in the genus Saocifraga. When several ovaries 
 are disposed upon the inner walls of a tubular calyx, they 
 are said to be parietal, as in Rosa, The compound ovary 
 often presents the appearance of a single body, divided 
 internally by partitions, PI. XIV., Fig. 179. 
 
 167. Dissepiments of the Ovary. As a single carpel 
 is analogous to a leaf, it never has an internal dissepi- 
 ment or partition, properly so called, although it may 
 present membranous lauiinas of various kinds. But when 
 several carpels unite to form a compound ovary, they, 
 being leaves folded inwards upon themselves, constitute
 
 106 OVULES. 
 
 a body which, on being cut across, generally presents 
 a number of dissepiments. These partitions are always 
 longitudinal or vertical, and are uniformly equal in num- 
 ber to the carpels. As the placenta is the enlarged 
 margin of the carpel, the dissepiment is always connected 
 with it; hence, a partition in an ovary not connected with 
 the placenta, is not a true dissepiment. The dissepi- 
 ments may alternate with the placenta, when the latter are 
 formed by the cohesion of the two margins of the same 
 carpel; or they may be opposite to the placentae, when the 
 latter are formed by the cohesion of the margins of con- 
 tiguous carpels. Sometimes, in a compound ovary, the 
 united sides of the carpels do not project so far into the 
 cavity as to meet the axis ; as in the Poppy. In this 
 case, the placentae are said to be parietal. Sometimes 
 also the dissepiments become obliterated, so as to leave 
 the placentae in the middle, forming what is called a free 
 central placenta; as in Lychnis. 
 
 168. The Ovules. The young seeds, or Ovula, are 
 small pulpy bodies, supported by the placenta, and, after 
 impregnation, becoming converted into perfect seeds, 
 capable of germinating. Being attached to the placentas, 
 or margins of the carpels, they are analogous in position 
 to the buds sometimes found on the edges of leaves ; but 
 their structure is different. The little stalk that supports 
 the ovule is a prolongation of the placenta, and is named 
 the funicidus by some, the podosperm by others. In 
 almost all cases the ovule is enclosed within the ovarium ; 
 but in the Coniferse and Cycadese, in which the carpels 
 are not involute, the ovules are exposed, or naked. At 
 first the ovule seems to be of a uniform pulpy nature, but 
 gradually discloses two integuments or sacs open at the 
 top, and a central part named the nucleus. The outer sac, 
 or coat, is named primine, the inner secondine, and the 
 nucleus frequently has a thin coat named the tercine.
 
 STYLE AND STIGMA. 107 
 
 These three parts are all connected at some point of their 
 surface, and at the apex of the first two is a passage 
 called ike foramen. 
 
 169. The Style. The style is the prolongation of the 
 summit of the ovary which supports the stigma. It may 
 be wanting, and the stigma is then said to he sessile, as 
 in poppy. When the ovary is composed of a single car- 
 pel, the style is also single ; and the number of the styles 
 corresponds with that of the carpels, though, when the 
 carpels are numerous, the styles may be united. 1. With 
 regard to its direction, the style is said to be lateral, when 
 it arises from the side of the ovary, as hi Rose ; basal, 
 or basilar, when it appears to spring from the base of the 
 ovary, as in Alchemilla ; included, when it does not pro- 
 ject beyond the mouth of the flower, as in Pea ; protruded, 
 or exserted, when elongated, so as to appear outside the 
 flower, as in Campanula ; vertical, when standing upright, 
 or in the axis of the flower, as in Lily ; ascending, when 
 curved upwards, as in Sage ; decimate, when inclined 
 toward the lower part of the flower, as in Dittany. 2. With 
 regard to its form, the style is termed filiform, when 
 slender, and of nearly equal thickness in its whole length; 
 subulate, or awl-shaped, when tapering towards the end ; 
 trigonal, when three-sided, as in Lily; daviform, or club- 
 shaped, when enlarged upward, as in Snow-flake ; peta- 
 loid, when expanded, thin, and resembling a petal, as in. 
 Iris. 3. With reference to its divisions, it may be simple, 
 without any division ; or divided. When the division does 
 not extend far, it is slit; when more prolonged, it is par- 
 tile. Thus, it may be bifid, or bipartite ; trifid, or tripar- 
 tite, <fec. 4. After fecundation, the style generally falls 
 off, in which case it is said to be caducous ; or it may 
 remain, and is then called persistent. 
 
 170. Ttie Stigma. The part which, in fecundation, 
 receives the pollen, is named the stigma. It is composed
 
 108 ADHESION OF FLORAL ORGANS. 
 
 of cellular tissue, and has its surface generally destitute 
 of epidermis, so that, from transfusion of its fluids, or 
 from secretion, it is usually moist. As already men- 
 tioned, it may he sessile, or, on the contrary, furnished 
 with a style. In many plants there is only one stigma, 
 while in others there are two, three, five, or many; the 
 number of stigmas being determined by that of the styles. 
 The stigma is generally terminal, or placed at the end of 
 the style ; but it is sometimes lateral, or occupying its 
 side, as in Ranunculus. Considered with reference to 
 various circumstances, it is named capitate, or globose, 
 when of a spherical or roundish form, as in Primrose; 
 hemispherical, when of the form of a half sphere, as in 
 Henbane; discoid, when flat, broad, and like a shield, as 
 in Poppy; stettate, when flat, and cut into several lobes, 
 as in Winter-green ; lobed, daviform, subulate, filiform, 
 &c. With respect to substance, it is fleshy, glandular, 
 or membranous. Its surface may be smooth, velvety, 
 downy, hairy, or feathery. 
 
 171. Adhesion of Floral Organs. It has been stated 
 that the sepals frequently cohere; that the petals, and 
 especially the stamens, are very often found in a state of 
 close cohesion, although disposed in several concentric 
 whorls. Cohesion occurs also between neighbouring 
 organs, which differ in nature from one another, as be- 
 tween sepals and petals, between petals and stamens, 
 between stamens and carpels, or between several of these 
 whorls at once. This principle of cohesion furnishes an 
 explanation of the following forms of flowers : 
 
 (1.) Tlialamifloral Arrangement. Each whorl of the 
 different organs is distinct from the others at their base, 
 arising separately from the thalamus or torus ; in other 
 words, each organ may be detached from the thalamus, 
 without involving the separation of any other organ ; 
 there is, in fact, no cohesion of floral organs. Examples
 
 RECAPITULATION. 109 
 
 occur in Ranunculus and Magnolia. In all these cases, 
 the stamens are hypogynoiis, and the ovary superior. 
 
 (2.) Calycifloral Arrangement. The petals and sta- 
 mens seem to grow from the calyx, owing either to the 
 base of these organs cohering with the calyx, or to the 
 torus adhering to the calyx in the part where the stamens 
 and petals grow. In these cases the stamens are termed 
 perigynous, as in the Rose. When the ovary adheres to 
 the calyx, the stamens seem to he developed from the 
 summit of the ovary, and are called epigynous. The 
 ovary is then said to be inferior, as in umbelliferous 
 plants. 
 
 (3.) Corolliftorcd Arrangement. The stamens simply 
 cohere by their filaments with the corolla; in these cases 
 the trace of the filament is usually seen upon the tube of 
 the corolla between the lobes. Examples occur in Con- 
 volvulus, and the labiate plants. 
 
 RECAPITULATION. 
 
 163. Of what parts is the germen or ovary composed ? 
 What is meant by Carpel ? To what is the carpel analogous ? 
 164. Describe the carpel in a general sense. In what flower 
 is the seed-vessel converted into a leaf ? Is the carpel often 
 sessile ? What is the Thecaphore ? What is a compound pistil ? 
 How are the carpels arranged in it ? 165. Explain the several 
 arrangements of the whorls of a compound pistil, as they occur 
 in Mallow, Geranium, Aconite, Ranunculus, and Rose. 166. 
 What forms does the Ovary assume ? What is meant by a supe- 
 rior or inferior ovary ? When are the ovules said to be parietal ? 
 167. Has a simple carpel Dissepiments? Are the dissepi- 
 ments ever transverse ? Is the dissepiment connected with 
 the placenta ? What is a parietal placenta ? Are the dissepi- 
 ments ever obliterated ? 168. What are the Ovules ? How 
 are they connected with the placenta? Are ovules always 
 inclosed in the ovary ? What is their structure ? 169. De-
 
 110 RECEPTACLE, DISK, AND NECTARY. 
 
 fine the Style ? Is it always present ? May there be more 
 styles than one ? When longer than the flower, what is it 
 termed? What directions may it have? Does it vary in 
 form ? Is it often divided ? How is it named as to duration ? 
 170. What is the Stigma ? What forms may it assume ? 
 Does it vary as to direction and consistence ? 171. Explain 
 the principle of cohesion, as it appears in the thalamifloral, 
 the calycifloral, and the corollifloral arrangements. 
 
 CHAPTER XV. 
 THE RECEPTACLE, DISK, AND NECTARY. 
 
 There are certain parts connected with the flower, 
 which, having been only incidentally spoken of in the 
 preceding pages, require to be here described. 
 
 172. The Receptacle. It has been stated, at p. 80, 
 that the top of the peduncle generally expands in some 
 degree, so as to form a kind of disk, from which the 
 floral whorls proceed. This part, then, is what is usually 
 termed the receptacle of the flower. But the term re- 
 ceptacle is used by botanists in different senses. Thus 
 it is by some considered as merely the part on which the 
 carpels or fruits are placed, PI. XVL, Figs. 208, 209, 
 and obtains the names of Torus and Thalamus. When 
 it rises in the form of a column and bears the stamens, 
 it haa been named Gonoplwrum. When elongated 
 and bearing on its summit the petals and stamens, it has 
 been called the Anthophorum. When it bears only the 
 ovarium, it has been designated as the Carpophorum or 
 Gynophorum. In this case it may be either a roundish 
 stalk, when it is named the Podogynium or Thecaphorum;
 
 DISK AND NECTARIES. Ill 
 
 or it may be much enlarged and fleshy, with numerous 
 ovaria, when it is named Polyphorum. When lengthened 
 into a tapering body, with the styles adhering, it bears 
 the name of Rostrum. These terms are perhaps useful 
 in describing particular families. 
 
 173. Tlie Disk. Between the base of the stamens and 
 that of the ovary is frequently a fleshy or glandular 
 body, of a yellowish or greenish colour, which, being va- 
 riously modified, has received various names. Very often 
 it assumes the form of a fleshy ring, surrounding the 
 base of the ovary, when it is named the Hypogynous Disk. 
 When formed of several knobs or glands, it has been 
 called the Epipodium. Sometimes it presents the ap- 
 pearance of a cup, and is named accordingly a Cyathiform 
 Disk. When enlarged and inserted, as it were, under the 
 ovary, to which it forms a kind of receptacle, it is the 
 Gyndbasis. All these varieties are hypogynous, or situated 
 beneath the ovary, or around its base; but when the 
 ovary is inferior, that is, when the perianth adheres to 
 its sides, the disk becomes epigynous; as in the plants 
 named Umbdliferce, in which it has been called the Sty- 
 lopodium. Sometimes also it is perigynous, or adheres 
 to the sides of the calyx; as in the Almond and Cherry. 
 
 174. Nectaries. Linnaeus gave the name of Nectary 
 to every part of the flower that contains or secretes a 
 saccharine fluid, or even to every supernumerary part of 
 a flower. Thus, the tube of monopetalous flowers, such 
 as Lamium album, and the base of the united petals of 
 others, as Trifolium pratense, are nectaries. Sometimes 
 it is a prolongation of the calyx, as in Tropceolum, 
 PI. XIII., Fig, 170; or of the corolla, as in Viola, and 
 Antirrhinum, Fig. 162 ; or a part of the petals, or of 
 some analogous organs, as in Aquttegia and Aconitum, 
 Fig. 171, 174. The curious fringed scales of Parnassia, 
 PI. XIV., Fig. 175, were also considered of this kind,
 
 112 ABORTION OP FLORAL ORGANS. 
 
 as were the disks mentioned in the preceding paragraph. 
 The scales on the claws of the petals of Ranunculus, 
 and the pits on those of the Lilies and Fritillaries, are 
 also nectaries; as are the coronal appendages of Nar- 
 cissus, and the inner minute scales of Grasses. If the 
 term be necessary, it seems expedient to restrict it to 
 those parts which actually secrete honey, the use of 
 which some conceive to be to attract insects, for the pur- 
 pose of assisting in dispersing the pollen. 
 
 175. Abortion of Floral Organs. All the floral organs 
 are liable to imperfect development, or to non-development ; 
 in other words, to be abortive, and thus to derange, in va- 
 rious ways, the symmetry of the flower. This may occur 
 accidentally, in consequence of injury or disease; or habi- 
 tually, in conformity with the nature of certain organs in 
 particular species. Habitual abortion sometimes occurs dur- 
 ing the flowering period, and is perceptible by our senses. 
 Many plants which have a determinate number of carpels 
 when the flower opens, retain only a certain number of 
 them during the period of the ripening of the fruit : a 
 trilocular ovary becomes a bilocular or unilocular fruit, 
 in consequence of the arrested growth of some parts, of 
 the destruction of dissepiments, and of their adhesion 
 to the adjoining membranes. This effect may take place 
 in the bud-state, and escape observation. The traces of 
 these premature abortions are sometimes very discernible. 
 Thus, in the Corolliflorae, there are generally five lobes to 
 the calyx; five to the corolla, alternating with those of 
 the calyx ; and five stamens alternating with the lobes 
 of the corolla ; but there may be only four stamens, 
 situated normally, while the fifth is replaced by an 
 antherless filament, or an imperfectly-formed anther, or 
 a little gland, or there may be no substitution at all. 
 In these cases, the fifth stamen is more or less abortive, 
 from some arrest of development. The place of the fifth
 
 MULTIPLICATION OF FLORAL ORGANS. 113 
 
 remains vacant, while the others are in their regular 
 state. 
 
 176. Abortion occurs more frequently, as the organ 
 is more distant from the circumference of the flower; 
 hence the calyx is rarely abortive ; the tube is, however, 
 frequently reduced to the condition of very thin mem- 
 brane, and the limb consists merely of hairs, or teeth, 
 as in Composites. The lobes are often wanting in Um- 
 belliferae. The corolla is entirely wanting in Capparidese, 
 in some Caryophylleae, and in many other cases. The 
 absence of the stamens or pistils is the more remarkable, 
 that their function is of great importance. Flowers 
 sometimes occur in the same species and on the same 
 stalk in which one of these organs is imperfectly de- 
 veloped in which the stamens have no pollen, or the 
 ovaries no ovules. Or one of these organs may fail 
 completely ; when this is constant, the plant is called 
 unisexual, as contradistinguished from perfect or her- 
 maphrodite plants. 
 
 177. Honochlamydeous Flowers. Many plants have 
 only one envelope to their flowers. This envelope is 
 single in some dicotyledons, as daphne ; double in most 
 monocotyledons, as in liliaceous plants. The term 
 perianth has been already noticed, as applied to this 
 envelope ; another term is perigonium, which merely 
 signifies the envelope surrounding the sexual organs ; 
 when there is only one whorl, the perigonium is simple; 
 when there are two, it is double. Deviations from sym- 
 metry and cohesions occur here, as in the other forms of 
 floral apparatus. 
 
 178. Multiplication of Floral Organs. It has been 
 observed that parts of a flower are sometimes abortive ; 
 on the other hand, the parts are sometimes multiplied 
 under certain circumstances. This is in great measure 
 
 H
 
 114 "DOUBLE" FLOWERS. 
 
 the origin of what are called " double" flowers. Multi- 
 plication of floral organs may occur in two ways : 
 
 1. The number of entire whorls may be multiplied. 
 
 2. The number of pieces of a whorl may be multiplied. 
 
 These multiplications may occur in an individual acci- 
 dentally, or they may be constant in varieties which have 
 been carefully cultivated. 
 
 (1.) Entire whorls of brads are added in dianthus 
 caryophyUus imbricatus. Instead of one pair there may be 
 from fifteen to twenty pairs, situated at right angles to each 
 other, and imbricated, sometimes preventing the growth 
 of the flower. Entire whorls of perigonium are added 
 in a variety of white lily, although the stamens are de- 
 veloped in the interior. The corolla, is multiplied in 
 datura fasluosa ; two or three whorls are placed concen- 
 trically within one another. In plants with numerous 
 stamens, the number of whorls varies considerably ; 
 and so with carpels, when they are numerous. This 
 kind of multiplication deranges the normal symmetry of 
 flowers ; but it is worthy of remark that supernumerary 
 whorls of petals, stamens, and carpels are always alter- 
 nate with the series immediately exterior to them. 
 
 (2.) The number of parts constituting a whorl may be 
 multiplied accidentally. Colchicum may have seven or 
 eight lobes, seven or eight stamens ; rue or syringa may 
 have four or five pieces. These multiplications are some- 
 times merely apparent, and are owing to the solution of 
 organs which are naturally in a state of cohesion. On 
 the other hand, a single organ may be replaced by a 
 bunch of similar organs: a fasciculus of petals occurs in 
 the place of each petal in a primula described by Decan- 
 dolle. 
 
 179. "Double 1 Flowers. Flowers with numerous 
 whorls, as those of nymphsea, pseonia, <kc., are probably
 
 RECAPITULATION. 115 
 
 produced by the tendency of these species to multiply 
 their organs. Or they may result from transformation: 
 flowers with five stamens and five petals may have ten 
 petals in two whorls ; here, the stamens have been 
 transformed into petals. Sometimes the anthers, at 
 other times the filaments, undergo this change ; but it is 
 generally the filament, which in such cases loses its 
 anther, and becomes plane and coloured like a petal. 
 When the anther is transformed, it changes into the 
 shape of a liorn : thus, there are two garden varieties of 
 aqidlegia vulgaris the one named stdlata, from transfor- 
 mation of the filaments ; the other corniculata, from 
 transformation of the anthers into horns. 
 
 RECAPITULATION. 
 
 172. What is commonly meant by the Receptacle ? When 
 is it named the Torus or Thalamus ? What is the Gono- 
 phore, Anthophore, Carpophore, Thecaphore, Polyphore ? 
 173. \\here is the Disk situated ? When is it hypogynous, 
 epigynous, and perigynous ? 171. What is meant by the term 
 Nectary ? What parts of plants secrete honey ? 175. What 
 is meant by abortion of floral organs ? How may this prin. 
 ciple operate, habitually, in the case of carpels and of stamens ? 
 176. What is the comparative frequency of abortion in the 
 several whorls of the flower ? 177. What are Monochlamy- 
 deous flowers ? What is the perigonium ? 178. In what 
 two ways does multiplication of floral organs occur ? Is any 
 order observable iu cases of multiplication of entire whorls ? 
 On what principles may the multiplication of portions of a 
 whorl be explained ? 179. What is meant by double flowers * 
 Oil what principles is this mode of multiplication explained ?
 
 116 THE FRUIT. 
 
 CHAPTER XVI. 
 
 THE FRUIT. 
 
 180. General Idea of the Fruit. The Fruit, Fructus, 
 PI. XIV., Fig. 179, 180, 181, 182, is the ovary or ger- 
 men arrived at maturity. Frequently there are con- 
 nected with it persistent bracteae, calyces, or corollas, 
 enlarged, and either dry or pulpy, which may also be 
 considered as forming part of it. It is composed essen- 
 tially of two parts, the pericarp and the seed, the former 
 enclosing the latter. By this character a small fruit 
 may be distinguished from a seed, as well as by its 
 often having on some part of its surface some trace of 
 the style or stigma. Many fruits, as those of the natural 
 families of the Umbelliferce, Labiatce, Boragineai, and 
 Grasses, were formerly considered as naked seeds, but 
 are now known to consist of seeds surrounded with a 
 pericarp ; the only naked seeds known being confined to 
 the families of Coniferce and Cycadece. 
 
 181. The Pericarp. The part of the fruit which im- 
 mediately invests the seed or seeds, and originally formed 
 the ovarium, is the Pericarp, Pericarpium. The base of 
 the pericarp is the part by which it is attached to the 
 peduncle, and its apex is indicated by the remains of the 
 style or stigma. The pericarp varies extremely iu size, 
 thickness, and texture ; being from a twelfth of an inch 
 to two feet or more in diameter, delicately membranous, 
 spongy, succulent, fibrous, cartilaginous, woody, or bony. 
 It is always formed of three parts : the Epicarp, Meso- 
 carp, and Endocarp. 
 
 182. 1. The epicarp is the external membrane or 
 skin of the fruit ; in the Cherry, PI. XV., Fig. 183, aud
 
 STRUCTURE OF THE PERICARP. 117 
 
 in the Pea, PL XIV., Fig. 182, it is the outermost deli- 
 cate covering or cuticle. It may readily he detached, 
 as a velvety skin, in the Peach, while in the Nectarine 
 and the Apricot it adheres to the mesocarp. 2. The 
 inesocarp is the layer which lies immediately beneath the 
 cpicarp ; it is sometimes so thin as to be hardly distin- 
 guishable ; in other cases it is thick, fleshy, or fibrous. 
 It is the dry fibrous part of the Almond, surrounding 
 the shell ; in the Peach, Apricot, and Cherry it is the 
 fleshy, eatable portion, and in these cases it is called 
 sarcocarp. 3. The endocarp is the innermost membrane 
 or shell, being, in the Pea, a thin, transparent coating, 
 and in the Peach, Apricot, and Cherry, the bony part 
 of the " stone." 4. These three portions of the pericarp 
 may adhere to one another in different degrees : in the 
 Peach, the three parts are easily separated from one 
 another; in the Nectarine, the Apricot, and the Almond, 
 the epicarp always adheres to the mesocarp, and this 
 latter separates spontaneously from the endocarp. In 
 the Apple, PI. XV., Fig. 184, the epicarp is formed by 
 the cuticle of the enlarged tube of the calyx, the meso- 
 carp is the pulpy mass formed by its parenchyma, and 
 the endocarps are the thin dry walls of the cavities con- 
 taining the seeds. The endocarps are here popularly 
 called the core. 
 
 183. Structure of the Pericarp. A fruit may be com- 
 posed of a single carpel or pericarp, or of several peri- 
 carps, either separate or united. When the carpels are 
 distinct, the fruit is said to be apocarpous; when coherent, 
 syncarpous. The structure of a single pericarp is well 
 illustrated by the common Pea, PI. XIV., Fig. 1 82, which 
 is a modified leaf, folded inwards, with the seeds attached 
 to the margins, which are united and thickened, to form 
 the placenta. When several carpels cohere, each carpel 
 generally forms a complete cell, and the fruit may thus
 
 118 DEHISCENCE OF FRUITS. 
 
 be bilocular, trilocular, quadrilocular, quinquilocular, or 
 muUilocular, one-celled, two-celled, <fcc. Sometimes, how- 
 ever, when the ovary is thus divided into several distinct 
 cavities, it undergoes modifications in the progress of its 
 development, and may ultimately present a single cavity, 
 or one divided by partial partitions. The walls of the 
 cells are named dissepiments, and are formed of the sides 
 of two contiguous carpels. The fruit of the Stramonium, 
 PI. XIV., Fig. 179, has four cells, formed by four im- 
 perfect dissepiments. The Apple has five cells, formed 
 of five carpels enveloped in a pulpy sarcocarp, and in- 
 closed in an epicarp composed of the calyx, PI. XV., 
 Fig. 184. 
 
 184. Dehiscence of Fruits. The cohesion of the mar- 
 gins of the carpel constitutes a suture or seam ; the 
 suture is said to be ventral or seminiferous, the former 
 term denoting that its position is opposite to the dorsal 
 vein of the carpel ; the latter denoting the development 
 of the seeds along the two sides of this line. Fruits are 
 said to be dehiscent or indehiscent, according as their 
 carpels open or remain closed, at the period of maturity. 
 The pieces which separate from one another in dehis- 
 cence are called valves. The suture, the dorsal vein, 
 and the two valves are familiarly exhibited in the Pea. 
 Dehiscence is longitudinal or transverse most com- 
 
 DESCRIPTION or PLATE XIV. Stamens, Pistils, and Fruit. 
 Fig. 174. Pair of Nectaries, in Acouitum. Fig. 175. Fringed 
 Nectaries of Parnassia. Fig. 176. A Stamen : a, the filament ; 
 b, the anther. Fig. 177. A Pistil : a, the germen ; b, the 
 style ; c, the stigma. Fig. 178. Capsule of a Mesembryan- 
 themum, open and shut. Fig. 179. Transverse section of the 
 Capsule of Datura, showing the partitions and columellas. 
 Fig. 180. A siliqua or Pod. Fig. 181. A silicula or Pouch. 
 Fig. 182. A Legume.
 
 CLASSIFICATION OF FRUITS. 119 
 
 raonly the former. 1. Longitudinal dehiscence is called 
 septicidal, when it takes place along the ventral sutures: 
 the dissepiments or septa of the contiguous carpels are 
 then separated from one another, as in Rhododendron. 
 It is locidicidal, when it takes place along the dorsal 
 veins : the loculi or cells are then divided at their backs, 
 as in Lilac. Or it may be septifragal, when the backs 
 of the carpels separate from the septa, which adhere to 
 the axis, as in Convolvulus. 2. Transverse dehiscence 
 is called circumscissile, when the pericarp is divided all 
 around by a transverse separation, as in Henbane and 
 Pimpernel. Many pericarps open irregularly ; in some 
 the seeds escape by pores or small valves which open at 
 the upper extremity, as in the pericarp of Poppy and of 
 Snap-dragon. 
 
 185. Classification of Fruits. There are three large 
 classes of fruits ; viz. simple or apocarpous fruits, or the 
 result of free carpels in one and the same flower; compound 
 or syncarpous fruits, formed by the cohesion of several car- 
 pels in the same flower ; and aggregate or polyanthocar- 
 pous fruits, formed by the cohesion of several fruits, of 
 different flowers. 
 
 DESCRIPTION OF PLATE XV. Fruit. Fig. 183. A Drupe. 
 Fig. 184. A Pome or Apple. Fig. 185. A Berry. Fig. 186. 
 A kind of Berry formed of an aggregation of little Drupes, 
 and called an Etserio. Fig. 187. Berry of Passiftora suberosa. 
 Fig. 188. Cone or Strobilus of the Larch. Fig. 189. Capsule 
 of a Moss, Splachnum, with its fleshy base or apophysis, a, 
 and its fringe or peristome, b. Fig. 190. Barren flower of a 
 Moss, after Hedwig, magnified. Fig. 191. Supposed stamens 
 with the pollen issuing, and the jointed filaments. Fig. 192. 
 Fertile flower of a Moss, consisting of numerous pistils. Fig. 
 193. Germinating seed of Gymnostomum pyriforme. Fig. 194-. 
 The same more advanced.
 
 120 SIMPLE OR APOCARPOUS FRUITS. 
 
 1 86. SIMPLE OR APOCARPOUS FRUITS. Of fruits simple 
 in structure, and of which only one series is produced by 
 each flower, the following are the most common : 
 
 1. Fottide, Fotticulus. A dry pericarp, having the ap- 
 pearance of a folded leaf, and opening by the ventral 
 suture, so that it may be considered as composed of a 
 single valve, along the margins of which the seeds are 
 disposed ; as in Vinca, Ccdtlia, and Ranunculus. 
 
 2. The Legume, Legumen. PL XIV., Fig. 182. A 
 pericarp formed of a single carpel, or leaf folded upon 
 itself, with the edges adherent, opening longitudinally 
 into two valves, by the ventral suture and the dorsal vein 
 simultaneously. The Legume differs from the Follicle 
 only in this latter circumstance. Sometimes, however, 
 it is indehiscent. When a Legume is contracted in the 
 spaces between the seeds, or when transverse partitions 
 are there formed, it is named a Lomentum. Examples 
 of the Legume are seen in the Pea, the Bean, Laburnum, 
 and other plants with papilionaceous flowers. The Lo- 
 mentum occurs in Ornithopus and some Acacias. 
 
 3. The N'ucula. PI. X., Fig. 126 ; PI. XVI., Fig. 
 201. A hard pericarp, of a horny or bony texture, in- 
 dehiscent, and containing a single seed, to which it is 
 not closely attached ; as in Lamium and Borago. It is 
 also named Nut, Nux ; but is not what is commonly 
 called by that name. The fruit of the Strawberry is a 
 collection of minute nucules, acini, or nuts, upon a con- 
 vex fleshy torus. The fruit of the Rose is an analogous 
 collection of nuts placed within a torus, which coheres 
 with the tube of the calyx, and becomes fleshy. This 
 particular fruit is termed Cynorrliodon. 
 
 4. The Drupe, Drupa. PI. XV., Fig. 183. An in- 
 dehiscent fruit of which the pericarp is thin, the meso- 
 carp very thick and pulpy, the endocarp hard. The 
 seed is single, although in the early state there are two,
 
 COMPOUND OB SYXCARPOUS FRUITS. 121 
 
 one of them usually becoming abortive. Examples are 
 seen in the Cherry, Peach, Plum, and Apricot. The 
 fruit of the Raspberry and the Blackberry consists of 
 numerous minute drupes, placed on a convex torus. 
 This arrangement is sometimes called Etcerio, PI. XV., 
 Fig. 186. 
 
 187. COMPOUND or SYNCARPOUS FRUITS. A com- 
 pound fruit is one composed of several united ovaria. A 
 fruit of this kind, as indicated by having several styles 
 or stigmas, may be simple, from the abortion of some of 
 its carpels, and then assumes the appearance of a simple 
 fruit. 
 
 5. The Caryopsis. This kind of fruit, which is pecu- 
 liar to the Grasses, is one-celled, one-seeded, indehiscent, 
 dry, with the pericarp so united with the seed as not to 
 be distinguishable from it. From having two or more 
 stigmas, the ovarium may be supposed to be of a com- 
 pound nature, although it never has more than one ovule. 
 
 6. Achenium, PI. XVI., Fig. 204. A one-seeded, 
 one-celled, indehiscent fruit, with the pericarp not adhe- 
 rent to the seed. Having two or more stigmas, the ova- 
 rium may, like the last, be supposed to be compound, 
 although there is never more than one ovule. All the 
 plants forming the natural order of Compositce have fruits 
 of this kind. The Diachemium, Fig. 206, composed of 
 two achenia, is the fruit of the Uiribdliferce. 
 
 7. Carceridus. A many-celled fruit ; the cells dry, 
 indehiscent, few-seeded, cohering round a common axis ; 
 as in Malva. 
 
 8. The Samara. A two-celled fruit ; the cells dry, 
 indehiscent, few-seeded, elongated into membranous ex- 
 pansions; as in the Ash, Elm, and Sycamore. 
 
 9. TheSiliqua. PI. XIV., Fig. 180. An elongated, 
 two-valved, many-seeded pericarp, having the seeds at- 
 tached to two lateral placentae, and a dissepiment formed
 
 122 COMPOUND OR SYNCARPOUS FRDIT3. 
 
 by a membrane, wbicli is a prolongation of tbe endocarp; 
 as in tbe Cabbage and Mustard. Tbe Silicula differs 
 merely in being proportionally broader ; PI. XIV., 
 Fig. 181. Tbese fruits characterise the Cruciferous 
 family of plants. 
 
 10. The Capwte, Capsula. PI. XIV., Fig. 178. 
 A dry, dehiscent, many-seeded, one-celled, or many- 
 celled pericarp ; as in Primula and SteUaria. PI. 
 XIV., Fig. 179, exhibits a transverse section of the cap- 
 sule of Stramonium, with its four cells, central placenta- 
 tion, and numerous seeds arranged round one of the 
 placentae. The fruit of Henbane, Pimpernel, and 
 Lecytbis, is a capsule, but it opens transversely, and has 
 hence received the name of Pysddium. 
 
 11. The Acorn, Glans. A one-celled fruit, with one 
 or few seeds, indebiscent, hard and dry, with its base 
 enveloped by an involucrum or cupule. The fruit of the 
 Oak, Hazel, and Chestnut, are of this kind. 
 
 12. The Gourd, Pepo. A one-celled, indehiscent, 
 fleshy fruit, with numerous seeds attached to parietal 
 pulpy placentae; as in the Melon and Cucumber. 
 
 13. Berry, Bacca. PI. XII,. Fig. 185. An inde- 
 hiscent, many-seeded, pulpy fruit; as in the Gooseberry 
 and Currant. The use of this term has been extended 
 to almost all fruits which are semi-liquid interiorly, and 
 indebiscent. In this sense it is opposed to the term 
 Capsule. It is said, for instance, that the Grape is a 
 berry, resulting from a free ovary, while the Gooseberry 
 is an adherent fruit. 
 
 14. The Apple, Pomum. PI. XII., Fig. 184. A 
 fruit consisting of several membranous or cartilaginous 
 carpels, containing few seeds, and embedded in a fleshy 
 mass, formed by an enlarged calyx; as in the Apple and 
 Pear. 
 
 15. The Hesperidium. A fleshy fruit, with a thick
 
 TERMS OF RARER OCCURRENCE. 123 
 
 envelope, and divided internally into several cells by mem- 
 branous dissepiments; as in the Orange and Lemon. 
 
 188. AGGREGATE or POLYANTHOCARPOUS FRUITS. In 
 these the floral envelopes or bracteas are enlarged and 
 thickened. 
 
 16. The Cone. The cone, or strobile, is an enlarged 
 catkin, the scales of which bear naked seeds. It is an 
 assemblage of sessile fruits, each consisting of a pericarp, 
 in the form of a convex scale, and of seeds situated at 
 the base of the pericarp, as in the Pine and the Fir. In 
 some cases the scales cohere, as in Juniper. 
 
 17. The Syconus. A fleshy, concave receptacle, en- 
 closing, more or less completely, some very minute, 
 distinct fruits, proceeding from a multitude of flowers, 
 as the Fig. 
 
 18. The Sorosis. A collection of carpels, of several 
 flowers, cohering by the enveloping parts of the floral 
 apparatus, of the bracts, and fleshy floral axes, which 
 adhere to one another, as in the Bread-fruit and the 
 Pine-apple. 
 
 189. Terms of Rarer Occurrence. According to the 
 number of seeds contained in a fruit, this is termed 
 oligospermous or polyspermous. The former contains 
 few, generally a determinate number of seeds ; in the 
 latter, the number is large and indeterminate. Fruits 
 in which the pericarp is very thin, and adheres closely 
 to the seed, are called pseudospermous, as in the Grami- 
 nese, Labiatse, Compositse, fcc. 
 
 In addition to the names of fruits, arranged and de- 
 scribed above, the following may be noticed : 
 
 19. Utricle. Utriculus. A simple or apocarpous, inde- 
 hiscent, membranous pericarp, elastic, sometimes burst- 
 ing transversely at its base, rather in consequence of a 
 shock, than by natural dehiscence, as in Amaranth. 
 
 20. Amphisarca. A compound or syncarpous, hide-
 
 124 TERMS OF RARER OCCURRENCE. 
 
 hiscent pericarp, rather hard than fleshy, containing 
 seeds in the cells surrounded with pulp, as in Crescentia 
 and Adansonia. 
 
 21. Nuculanium. A compound or syncarpous, inde- 
 hiscent fruit, with fleshy mesocarp, and pulp in the cells ; 
 it is in fact a berry, not adherent to the calyx. The 
 name is little used, the term berry being often employed 
 for it, as in the grape. 
 
 22. Conceptaculum. A compound or syncarpous, de- 
 hiscent fruit, formed of two follicles cohering at their 
 back. The name of double follicle is often used, as in 
 several Asclepiadacese. 
 
 23. Diplotegia or Adherent Capsule. A compound or 
 syncarpous, dehiscent fruit, consisting of a capsule co- 
 hering with the calyx or perigonium, as in Campanula. 
 These fruits are commonly called Capsules, owing to the 
 extension of the term by the old botanists, who had not 
 discovered the principle of the cohesion of organs. In 
 description, it is right to say whether the ovary is free 
 or adherent, and hence, when a capsule is spoken of, it 
 is at once understood whether it is adherent, or a true 
 capsule. 
 
 24. Cremocarpium. This is the compound or syn- 
 carpous, indehiscent fruit of the Umbelliferse, Araliacese, 
 &c., consisting of two or more carpels cohering with 
 the tube of the calyx, and interiorly with the single seed. 
 At a certain period, the carpels, called mericarps, when 
 there are two, separate from below upward, and burst 
 the tube of the calyx, a portion of which remains at- 
 tached to the back of each. This fruit is also termed 
 diakenium, pentdkenium, polakenium, according to the 
 number of akenia composing it. 
 
 25. Balausta. A compound or syncarpous, indehis- 
 cent, multilocular, adherent fruit, with a hard envelope; 
 its seeds surrounded by pulp without losing their points
 
 RECAPITULATION. 125 
 
 of attachment. The cells are superposed, owing to the 
 presence of two whorls of carpels, which adhere, the one 
 above the other, to each other, and to the tuhe of the 
 calyx a circumstance which can he ascertained only in 
 the flower-state. It occurs in the Pomegranate. 
 
 RECAPITULATION. 
 
 180. What is meant by the term fruit ? Of what parts 
 does it essentially consist ? How are minute fruits in some 
 cases distinguished from seeds ? Are there any naked seeds ? 
 181. What is the pericarp ? How are the base and the apex 
 of the pericarp determined ? Into what parts is the pericarp 
 divisible? 182. Describe the epicarp, the mesocarp, and 
 the endocarp of diiferent fruits. Explain their modes of 
 cohesion with one another. 183. Distinguish between apo- 
 carpous and syncarpous fruits. What is meant by a multi- 
 locular fruit ? What are dissepiments ? Explain the structure 
 of the fruit of the stramonium and of the apple. 184. What 
 is a suture ? Distinguish between the ventral suture and the 
 dorsal vein of a carpel. What is meant by dehiscence ? 
 Explain and give examples of septicidal, loculicidal, septifra- 
 gal, and circumscissile dehiscence. What are the valves of a 
 carpel? 185. Describe the three classes of fruit. 186. 
 What are the principal simple or apocarpous fruits ? Describe 
 the follicle. In what respect does the legume differ from the 
 follicle, and from the lomentum ? What is the nucule ? 
 Explain the structure of the fruit of the strawberry and of 
 the rose. What is a drupe ? Describe the fruit of the 
 raspberry and of the blackberry. What is the etserio ? 187. 
 What is a compound fruit ? In what cases does it assume 
 the appearance of a simple fruit ? Describe the caryopsis 
 and the achenium, the carcerule, and the samara. Distinguish 
 between the siliqua and the silicula. Describe the Capsule, 
 and state in what respect it differs from the berry. Describe 
 the Glaus, the Pepo, and the Berry ; the Pome and the Hes- 
 peridium. 188. What are aggregate fruits? Describe the
 
 126 THE SEED. 
 
 Cone, the Syconus, and the Sorosis. 189. What terms are 
 applied to fruits with reference to the number of their seeds ? 
 What is the Utricle ? What is the Amphisarca ? Describe 
 the Nuculanium and the Conceptaculum. What is the 
 Diplotegia ? lu. what does it differ from the true capsule ? 
 Explain the Cremocarpium. Give the name and structure of 
 the fruit of the Pomegranate. 
 
 CHAPTER XVII. 
 THE SEED. 
 
 1 90. Nature of the Seed. The fecundated and matured 
 ovule is the seed, a body inclosed within the pericarp, 
 and containing an organized embryo, which, on being 
 placed in favourable circumstances, is developed into an 
 individual, similar to that from which it derived its origin. 
 The reproductive organs of flowerless plants, as sea-weeds 
 and fungi, differ in structure, and in their mode of ger- 
 mination ; and are not considered as true seeds, but are 
 named spondes. The seed is attached to the placenta by 
 a small pedicle or umbilical cord, sometimes called the 
 podosperm. In some plants this cord is unusually expanded 
 into a partial covering of the seed, called the arillus ; 
 this body constitutes the mace, which irregularly envelopes 
 the Nutmeg. The seed consists essentially of an exter- 
 nal skin, called spermoderm, or perisperm, and a nucleus, 
 or kernel. 
 
 191. Spermoderm, or Perisperm. The spermoderm, 
 or skin of the seed, consists, in a general sense, of three 
 envelopes : the exterior one is the testa, the interior the 
 endopleura, and the intermediate the mesosperm. These 
 distinctions, adopted for the purpose of establishing an
 
 NUCLEUS OR KERNEL. 127 
 
 analogy between the spermoderm and the leaf, are not 
 commonly appreciable ; if parts of the ovule, correspond- 
 ing to them, as primine, secundine, and tercine, really 
 exist in the seed, their conditions are usually masked by 
 cohesion. The surface and the form of seeds vary con- 
 siderably. The seed separates from its support, leaving 
 a scar, called the hilum, cicatricula, or umbilicus ; this 
 part is sometimes very small, but in some cases it is 
 remarkably large, as in the Horse-chestnut, in which it 
 is of a whitish colour. This part always indicates the 
 true base of the seed. The centre of the hilum, through 
 which the nutrient vessels pass into the interior, is called 
 the omphalodium. At the summit of some seeds, as of 
 the Orange and the Almond, a brown spot is observed, 
 formed by the union of certain vessels which proceed from 
 the hilum ; this spot is the clialaza, and it is connected 
 with the hilum by a bundle of vessels which pass along 
 the face of the seed, and is termed the raphti. 
 
 192. Nucleus or Kernel. The nucleus of the seed is 
 the body contained within the spermoderm, and it con- 
 sists of the embryo and albumen, or of the embryo alone ; 
 the latter being the essential part of the nucleus. 1. 
 The albumen, when present, incloses the embryo ; it varies 
 considerably in consistence, being fleshy, farinaceous, 
 oily, horny, or bony. In many plants, as the Grasses, 
 the albumen constitutes a very nutritious fecula or farina. 
 It sometimes exists in very small quantity ; in other 
 cases it is abundant, and exceeds the embryo in size. 
 An important distinction derived from the presence or 
 absence of albumen, is that of albuminous and exalbu- 
 minous seeds. 2. The embryo is the young plant, and 
 it is composed of three parts, viz., the radicle, the plumule, 
 and the cotyledon, or cotyledons. 
 
 193. The Radicle. The radicle is a simple, minute 
 root, PI. I., Fig. 4, f t commonly thin and pointed, furm-
 
 128 THE COTYLEDONS. 
 
 ing one extremity of the embryo, and, when germination 
 takes place, giving rise to the root. The direction of 
 the radicle determines the position of the embryo, as it 
 always points toward a small hole, the foramen, in the 
 testa or outer coat of the seed. As this aperture may 
 be placed near the hilum, or at a distance from it, or 
 even on the opposite side, the embryo will be erect, in- 
 verse, or transverse. Sometimes the radicle is external 
 and exposed ; sometimes covered and concealed by a 
 body or sheath named the coleorrhiza, which it^bursts iu 
 germinating; and less frequently incorporated with the 
 albumen. These circumstances have given rise to a 
 division of plants into Exorrhizous, JEiidorrhizous, Synor- 
 rhizous, with which correspond the Dicotyledonous, 
 Monocotyledonous, and Polycotyledonous plants, the last 
 being the Coniferaj and the Cycadese. 
 
 194. The Plumule. The plumule is the young stem, 
 which is to be developed into the stem, leaves, and 
 flowers of the new plant. It is sometimes scarcely per- 
 ceptible in the seed; in other cases it is as long as the 
 radicle. It consists of two parts the caulide, or little 
 stem, and the gemmule, or little bud. These parts are 
 distinctly seen in PI. I., Fig. 4, 9, in which the seed has 
 germinated ; here the spermoderm is ruptured, the 
 radicle is represented as descending, the plumule as 
 ascending, with its gemmule at the summit, composed 
 of the rudiments of all the parts which are to be deve- 
 loped in the air. 
 
 195. The Cotyledons. The cotyledonary body is some- 
 times simple and undivided, thus constituting a single 
 cotyledon, as in Grasses and other endogenous plants; 
 sometimes formed of two cotyledons united at their base. 
 Plants whose embryos have a single cotyledon are named 
 monocotyledonous, while those which have two cotyledons 
 form the class of dicotyledonous plants. Sometimes there
 
 DICOTYLEDONOUS EMBRYO. 129 
 
 are more than two cotyledons, as in the Pines and other 
 Conifera?, in which the number varies, in different 
 species, from three to twelve. PI. I., Fig. 2, represents 
 the seed of Pinus Cembra, having about twelve coty- 
 ledons; and Fig. 3, a young plant of the Norfolk Island 
 Pine, which has four cotyledons. In plants destitute of 
 albumen, the cotyledons are generally thick, and in those 
 furnished with that organ, thin. It is therefore probable 
 that they supply nourishment to the young plant. After 
 germination, they become thinner, are raised to the sur- 
 face, acquire a green colour, and become the first or 
 seminal leaves, as in Lupine and Sycamore ; in this case 
 they are said to be epigeal. But sometimes they remain 
 under ground, and are named hypogeal, as in the Bean. 
 The cotyledons are frequently straight, but they may 
 also be arcuate, spiral, undulated, and of various forms. 
 They are usually placed face to face, but are often sepa- 
 rated to some distance. When folded with their back to 
 the radicle, they are said to be incumbent, and when 
 their edges are presented to that part, they are accum- 
 bent; these peculiarities occur in cruciferous plants : the 
 cotyledons are incumbent in the Stock, accumbent in the 
 Wall-flower. In the Cabbage, they are folded upou 
 themselves, and are then said to be conduplicate. 
 
 196. Dicotyledonous JSmbryo. In the embryo, of 
 which the Cotyledonary Body has two distinct lobes, the 
 radicle is cylindrical or conical, exposed, protruded, and 
 elongates at germination so as to become the true root 
 of the plant. The two cotyledons are attached to the 
 caulicle at the same height, opposite to each other, and 
 are generally thick. The gemmule is contained between 
 the cotyledons, by which it is more or less concealed. 
 Sometimes, however, the two cotyledons are intimately 
 united, as in the Horse-Chestnut; or they are increased 
 in number, as in the Couiferse; or are accidentally ab-
 
 130 MONOCOTYLEDOSTOUS EMBRYO. 
 
 sent, as in Cuscuta. In germination, the radicle elon- 
 gates and becomes the root, the cotyledons rise above 
 the ground, and are converted into leaves, and the gem- 
 inule unfolds itself into the stem, foliage, and flowers. 
 
 197. Monocotyledonous Embryo. In monocotyledo- 
 nous plants the embryo is generally a cylindrical or ob- 
 long, undivided, homogeneous body, in which there is no 
 obvious distinction of radicle, plumule, or cotyledons. 
 In germination, the upper end swells and remains within 
 the perisperm, while the lower elongates, and emits one 
 or several radicles, shooting downwards, and a slender 
 green body, protruding from its upper portion, and rising 
 into the air. The upper part remaining within the testa 
 is the single cotyledon; the radicle is at first enclosed in 
 the coleorhiza, which it bursts ; and the gemmule, also 
 contained in the interior of the cotyledon, is composed of 
 leaflets enclosing each other, the outermost usually 
 covering the rest. 
 
 198. With reference to the foregoing statements, it 
 will be advisable for the reader to examine a few seeds. 
 
 1. In the Orange, the seed is pendulous, occasionally 
 containing more than one embryo. The raphe and cha- 
 laza are distinctly marked. The embryo is straight ; the 
 cotyledons thick and fleshy ; the plumule conspicuous. 
 
 2. In the Almond, the seed is suspended, in consequence 
 of the cohesion of an umbilical cord, arising from the base 
 of the ovary, with its side. The embryo is straight, the 
 radicle pointing to the hilum. The cotyledons are thick; 
 albumen, none. 3. In the Nutmeg, the seed is nut-like, 
 enveloped in an arillus, or the mace. Albumen, between 
 fatty and fleshy, of a variegated appearance, termed 
 ruminate. The embryo is small; cotyledons, foliaceous; 
 the plumule conspicuous. 
 
 199. Classification. As it has already been stated 
 that the exogenous stem usually corresponds with a reti-
 
 RECAPITULATION. 131 
 
 culate leaf and a flower with five or four petals, and 
 the endogenous stem with a parallel-veined leaf and a 
 flower with three petals, it may here be added, that the 
 dicotyledonous embryo corresponds with the former, the 
 monocotyledonous with the latter class. Hence, a dico- 
 tyledonous plant is, in other terms, an Exogen; a mono- 
 cotyledonous, an Endogen. 
 
 RECAPITULATION. 
 
 190. Give a general account of the Seed. What is a Spo- 
 rule ? How is the seed attached to the placenta ? What is 
 the Arillus ? Of what parts is the seed composed ? 191. 
 Describe the Spermoderm. What is the Hilum, the Omphalo- 
 dium, the Chalaza, and the Raphe? 192. Of what is the 
 Kernel composed ? Is the Albumen always present ? What 
 are the position and general characters of the Albumen ? What 
 parts enter into the composition of the Embryo ? What 
 different positions may it assume ? 193. What names are 
 given to plants with reference to the position of the radicle ? 
 194. What is the Plumule ? Into how many parts is it 
 divided ? 195. Give an account of the Cotyledonary Body. 
 What is meant by Monocotyledonous and Dicotyledonous ? 
 Are there ever more than two Cotyledons ? Do the cotyledons 
 vary in form and direction ? Why are they distinguished into 
 epigeal and hypogeal ? When are they said to be incumbent, 
 accumbent, and conduplicate ? 19G. Describe the Dicotyle- 
 donous Embryo. 197. Describe the Monocotyledonous Em- 
 bryo. 198. Describe the seed of the orange, of the almond, 
 and of the nutmeg. 199. State the relations subsisting 
 between the structure of the seed and that of the leaf, of the 
 flower, and of the stem.
 
 132 FLOWERLESS PLANTS. 
 
 CHAPTER XVIII. 
 FLOWERLESS PLANTS. 
 
 200. General Remarks. The preceding chapters have 
 been devoted to two large classes of plants, viz., the 
 dicotyledonous or exogenous, and the monocotyledonous 
 or endogenous ; all the plants composing these two 
 classes are furnished with flowers. There remains 
 another large class, in which there are no cotyledons or 
 flowers. These are commonly called cryptogamic plants, 
 owing to the concealed nature of their organs of repro- 
 duction, and as distinguished from both the other classes, 
 which, from having these organs manifest, are called 
 phanerogamic. They are also called cellular plants, ow- 
 ing to their being formed of cellular tissue only, or of 
 cellular tissue and ducts. Their reproductive organs, 
 which are termed spores or sporules, are minute granular 
 bodies, having no distinct parts, but germinating from 
 any point of their surface. Flowerless plants form the 
 lowest series of the vegetable kingdom ; and it is in 
 some of these that a transition is exhibited to some of 
 the simplest forms of animals. The principal families of 
 flowerless plants are Ferns, Mosses, Lichens, Fungi, and 
 Algse. 
 
 201. Ferns. The Ferns are the largest of those plants 
 which are destitute of floral organs. They consist of a 
 number of leaves, named Fronds, attached to a stem, 
 which is either a subterranean rhizoma, or rises, like 
 the trunk of a tree, to the height sometimes of fifteen 
 or twenty feet. Their stem is formed by the cohesion of 
 the bases of the petioles round a cellular axis. Their 
 fronds are sometimes simple, but more frequently divided,
 
 LYCOPODIACE.E. 133 
 
 or variously decompounded, and in vernation are rolled 
 up. The reproductive organs consist of Tliecce, or minute 
 capsules, aggregated into little masses named Sori, of 
 various forms, and variously arranged on the back of the 
 frond, or along its margins. The thecae are either pedi- 
 cillate, and surrounded by an elastic ring, PI. XI., Fig. 
 145, or sessile, and destitute of a ring. When the sori 
 originate beneath the cuticle, they force it up in the 
 form of a delicate covering, called Indusium or Involu- 
 crum, PI. XL, Fig. 144. The Sporules, or reproductive 
 germs, are extremely small, and disposed without order 
 within the thecae. These plants approach in form, as 
 well as structure, to the flowering plants, especially the 
 Cycadece and Coniferce. 
 
 202. Equisetacece. These are herbaceous perennial 
 plants, with simple or branched, generally hollow, longi- 
 tudinally striated stems, jointed at intervals, and having 
 sheaths at the joints. The organs of reproduction are 
 arranged in a terminal spike or catkin, composed of 
 peltate scales, on the lower surface of which are Cap- 
 sides or thecse, filled with Granules of two kinds, some 
 very minute, others larger, and enfolded by four elastic 
 filaments. These larger granules are the reproductive 
 Sporules. 
 
 203. MarsileacecB, These are small aquatic plants, 
 of which the reproductive organs are a kind of leathery 
 Involucres, with one or more cells, containing Spondes, 
 and placed at the base of the leaves. 
 
 204. Lycopodiacece. These are intermediate in ap- 
 pearance between Mosses and Ferns. They are either 
 stemless, with erect subulate leaves, or they have creep- 
 ing stems and imbricated leaves. The organs of repro- 
 duction are sometimes small, globular, or reniforui 
 single-celled Capsules, containing numerous sporules, 
 sometimes larger capsules opening by two or three valves,
 
 134 MOSSES. 
 
 and containing only a few large granules. The capsules 
 are sometimes axillar and solitary, sometimes aggregated 
 in the axils of bractese, forming simple or digitate spikes. 
 205. Mosses. The Mosses are small plants entirely 
 composed of cellular tissue, but having a distinct axis of 
 vegetation, or stem, covered with leaves. Their repro- 
 ductive organs are of two kinds : axillar, cylindrical, or 
 fusiform bodies, containing minute roundish particles ; 
 and Thecce or capsules, supported upon a stalk or Seta, 
 covered with a Caly^tira, closed by an Operculum, within 
 which is a Peristome, composed of slender processes, 
 
 DESCRIPTION OF PLATE XVI. Seeds. Tig. 195. The 
 same as Tig. 194, more advanced, and become a young plant, 
 showing leaves and radicles. Fig. 196. Young plant of 
 Funaria hygrometrica. Pig. 197. Powdery wart of a Lichen, 
 presumed to be its barren flower. Tig. 198. Vertical section 
 of the shield or fruit of a Lichen, showing the seeds imbedded 
 iu its disk. Fig. 199. Section of the seed of a Date, Phoenix 
 Dadylifera, from Gcertner, having a lateral cell in the albu- 
 men, in which the embryo is lodged. Fig. 200. Section of 
 the Vitellus of Zamia, with its embryo. Fig. 201. Hough 
 coats of the seeds in Cynofflossum. Fig. 202. Fruit of a Carex. 
 Fig. 203. Seed of Afzelia, with its cup-shaped arillus. Fig. 
 204. Pappus or seed-down of a Tragopogon, being a calyx sur- 
 mounting the pericarp. Fig. 205. Tail of the seed in Dryas. 
 Fig. 206. Beaked fruit of Scandix, its two achenia separated from 
 the base. Fig. 207. Winged seed of Embothrium. Fig. 208. 
 Section of the conical, hollow receptacle of the Daisy. Fig. 
 209. Cellular receptacle of Onopordum. Fig. 210. Ligulate 
 floret, having a stamen and pistil, in the Dandelion. Fig. 
 211. Ligulate floret, having a pistil, but no stamens, in the 
 Daisy. Fig. 212, Tubular floret, from the disk of the Daisy. 
 Fig. 213. Capsule of a Moss, with a double peristome or 
 fringe, the operculum shown apart. Fig. 214. A portion of 
 the same peristome magnified, and showing the teeth.
 
 LICHENES. 135 
 
 named Teeth, and having a central axis or CdumeUa, the 
 space between which and the walls of the theca is filled 
 with minute Sporules. In PI. XII., Fig. 150 represents 
 a portion of moss with its theca and operculum ; Fig. 
 151, the calyptra. PI. XVI., Fig. 213, shows the seta, 
 theca, peristome, and operculum, of a moss ; Fig. 214, 
 the teeth of the peristome. The other bodies spoken of 
 above are represented by PL XV., Figs. 190, 191, 192, 
 The reproductive sporule, Fig. 193, is seen in the pro- 
 cess of germination in Fig. 194 ; and PL XVI., Fig. 
 195, shows the same farther advanced.; while Fig. 196 
 shows another moss in the same state. 
 
 206. Hepaticce. The Liverworts or Hepaticce are 
 small plants, having a loosely cellular substance, and 
 presenting the appearance of simple or lobed membranes, 
 furnished with a midrib, or having a small branched 
 stem bearing leaves. The reproductive organs are either 
 oblong or globular bodies, containing a minutely granu- 
 lar substance, escaping by an aperture, or Capsules con- 
 taining numerous sporules mixed with spiral filaments, 
 covered at first with a Calyptra, at length rising on a 
 peduncle, and opening into two or four valves. PL XII., 
 Fig. 152, represents one of these globular capsules, with 
 its calyptra. 
 
 207. Lichenes. The Lichens vary in form and tex- 
 ture, but may be defined as composed of fronds or Thatti, 
 presenting the appearance of membranous, powdery, lea- 
 thery, or gelatinous crusts or expansions ; simple or va- 
 riously lobed ; spreading on the ground, on rocks, stones, 
 the bark of trees, and dead wood. The reproductive or- 
 gans are of two kinds : Soridia, or heaps of pulverulent 
 bodies scattered over the surface of the thallus, PL XVI., 
 Fig. 197 5 or Apoihecia, varying in form and colour, Fig. 
 198, and enclosing the sporules. 
 
 208. CJiaracecB. These are aquatic plants, having
 
 136 STRUCTURE OF A COTYLEDONS. 
 
 slender, branched, green stems, with verticillate leaves, 
 on the upper of which are Capsules, each surrounded by 
 two or three bractese, and containing numerous sporules. 
 There are also on the branches sessile and rounded tuber- 
 cles of a reddish colour. 
 
 209. Algce. These plants are aquatic, some growing 
 in the sea, others in fresh water. They are destitute of 
 leaves properly so called, and present various forms, being 
 globular, filamentary, tubular, or laminar, simple or 
 branched, continuous or articulated. Their organs of 
 reproduction are minute Sporules, contained in Sporidia, 
 variously grouped, and usually placed in the substance of 
 the plants. All the plants named Sea-weeds belong to 
 this family. 
 
 210. Fungi. The Fungi are extremely diversified in 
 form, consistence, and colour ; being globular, oval, cup- 
 shaped, elongated, filamentary, simple or branched, and 
 composed of congeries of cellules. Their reproductive 
 organs consist of Sporules lying loose in the cellular tis- 
 sue, or enclosed in membranous cases or sporidia. Many 
 of them have a form resembling that of an umbrella, 
 being furnished with a PiLeus or convex part, having on 
 its lower part Tubes or Laminae, and a central or lateral 
 Stipe. Fig. 154, PI. XII., represents a mushroom co- 
 vered with its Volva. Fig. 153 shows the stipe and 
 pileus of another, with the former having upon it an 
 Annulus, being the remains of the volva. These plants, 
 together with the Algse, are considered as forming the 
 lowest or least organized of the vegetable series. 
 
 211. Structure of Acotyledons. It was stated, $$ 29, 
 30, that, on account of their peculiar mode of growth, 
 the stems of Dicotyledonous trees are named Exogenous; 
 those of Monocotyledonous trees, Endogenous. Another 
 term, Acrogenous, has been applied to the stems of 
 Ferns, which are cylindrical, usually hollow, or, if solid,
 
 CENTRIFUGAL GROWTH. 137 
 
 having the central part composed of a spongy suhstance, 
 destitute of woody fasciculi or medullary rays, and hav- 
 ing their external part composed of very hard plates 
 folded upon themselves. These plates, on being once 
 formed, continue without change as to number or quan- 
 tity, and seem to be prolongations of the woody matter 
 lying within the stalks of the leaves. Stems of this 
 kind differ in structure from those of exogenous plants, 
 which increase by addition to the outside of their wood, 
 and from those of endogenous plants, which increase by 
 addition of woody or vascular fibres to their interior. 
 They seem to undergo little or no enlargement in diame- 
 ter, and merely to elongate by the extension of their 
 summit, whence the term Acrogenous, by which they are 
 distinguished. 
 
 212. Centrifugal Growth. Another mode of growth, 
 termed Centrifugal, is that of fungi, lichens, and other 
 acotyledonous plants, which consist either of a spongy 
 mass, or of filaments radiating from a common centre. 
 " In an obscure plant called Marchantia, Mirbel found, 
 that a little thin green plate was first formed by the 
 action of the reproductive granules ; and that it was 
 from the edges of this plate, when once fully formed, 
 that all the succeeding expansions took place, as from a 
 common centre, but always upon the same plane ; so 
 that in such plants the central part is the oldest, and 
 the circumference the youngest. This is very apparent 
 in lichens, which, when very large, are always dead in 
 the centre, while they continue to go on growing from 
 every part of their margin. Fairy rings are an exem- 
 plification of the same thing in fungi. These appear- 
 ances are external indications of the centrifugal growth 
 of the subterranean stems of certain Agarics, which 
 originally spring from a common point, continually 
 spreading outwards upon the same plane, the central or
 
 138 RECAPITULATION. 
 
 first-formed parts perishing as the circumferential or 
 latest-formed parts develope." 
 
 RECAPITULATION. 
 
 200. What are the families of Plowerless Plants ? Explain 
 the terms phanerogamic and cryptogamic. What are Spores ? 
 201. Give a general account of Perns. 202. Describe the 
 Equisetaceae. 203. What are the Marsileaceae ? 204. What 
 plants do the Lycopodiacese resemble ? Describe their organs 
 of fructification. 205. What parts are observed in the theca 
 or capsule of a Moss ? 206. Describe the reproductive organs 
 of the Hepaticse. 207. Where do Lichens grow ? What are 
 their Soridia and Apothecia ? 208. Describe briefly the 
 Characese. 209. Of what nature are the reproductive organs 
 of the Algae. 210. What parts are observed in the Mush- 
 rooms properly so called ? 211. Why are the stems of Perns 
 said to be Acrogenous ? Give an account of their structure. 
 212. In what plants is the Centrifugal mode of growth ob- 
 served ?
 
 SECTION II. 
 FUNCTIONS OF PLANTS. 
 
 CHAPTER XIX. 
 
 GERMINATION, GEOWTH, AND MATURATION OF 
 * PLANTS. 
 
 213. GERMINATION. Plants being destitute of sensi- 
 bility and voluntary motion, have a less complex struc- 
 ture than animals, to which these faculties are essential. 
 Fixed in a particular spot, they increase in size by im- 
 bibing the nutritious elements by which they are sur- 
 rounded, are acted upon by the atmospherical agents, 
 and having reached the term of their annual or final 
 development, produce embryos of future individuals of 
 their species. Their functions are thus confined to nu- 
 trition and reproduction, the most intelligible mode of 
 observing which is to trace a plant from the commence- 
 ment of its growth to the completion of its organization. 
 Every plant originates from an impregnated ovule which 
 has been converted into a ripe and perfect seed. The 
 act by which a seed, on being placed in suitable cir- 
 cumstances, becomes developed so as to produce a plant 
 similar to that from which it sprang, is named Germi- 
 nation. 
 
 214. Conditions of Germination. The agents essen- 
 tial to this process are heat, moisture, and air. If a 
 seed be put into a place, the temperature of which is 
 below the freezing point, it remains torpid. On the other 
 hand, if the heat be very high, the seed is quickly dried
 
 140 PHENOMENA OF GERMINATION. 
 
 up, or, if kept moist, is softened and deprived of its 
 vitality. But if the temperature be moderate, and other 
 circumstances favourable, it soon begins to germinate. 
 Moisture is equally necessary, but must also be supplied 
 in moderate quantity. It softens the covering of the 
 seed, which is often very hard, rendering it more easy 
 for the embryo to burst it ; and it aifords a vehicle to the 
 substances which nourish the young plant. Atmospheric 
 air is not less necessary; for seeds buried to such a depth 
 as to be beyond its influence, remain in torpidity. But 
 light, instead of accelerating the development of the em- 
 bryo, seems to retard it, and seeds are found to ger- 
 minate readily in darkness. The conditions required for 
 germination, then, are access to moisture and air, and a 
 moderate temperature. These conditions are frequently 
 found to exist in the ordinary circumstances in which 
 seeds are left after dropping from the plants which pro- 
 duced them, but are more surely obtained by the inter- 
 ference of man, whose ingenuity enables him to place 
 them in the most favourable circumstances. 
 
 215. Phenomena of Germination. 1. The first evi- 
 dent effect of germination is the swelling of the seed, and 
 the softening of its envelopes. The latter burst after a 
 certain time, irregularly in some seeds, but regularly in 
 others. The period which elapses between the time 
 when seeds are placed in a situation favourable to their 
 development, and the time of germination, varies from a 
 few days to two years. Thus, the common Cress ger- 
 minates in two days, the Turnip in three, the Lettuce in 
 four, Grasses in a week, Hyssop in a month, many Pines 
 in a year, and the Hazel and Holly not until two years. 
 2. The next effect is of a chemical nature, and is called 
 decarbonization. In order to understand this process, ifc 
 must be known that, during the ripening of the seed, a 
 large quantity of carbon is fixed in its tissue, for the pur-
 
 PHENOMENA OF GERMINATION. 141 
 
 pose of insuring its durability. But this carbon Avill not 
 readily dissolve in water, and must therefore be got rid 
 of, in order to render the albumen and cotyledons avail- 
 able for nourishing the embryo. As an instance of this, 
 it was found by Senebier that unripe peas germinate 
 more rapidly than those which are ripe, the former con- 
 taining more liquid water, and less carbon. Accordingly, 
 in germination, the oxygen of the air unites with the 
 carbon of the seed, producing carbonic acid, which is 
 expelled; and the remaining substances are converted 
 into saccharine matter, which supplies nutriment to the 
 embryo. Hence it appears, that, during germination, a 
 seed undergoes a process exactly the reverse of that 
 which takes place during its maturation: in the one pro- 
 cess, it faces carbon; in the other, it discharges it. 
 
 216. Illustration of the Phenomena of Germination. 
 The process of converting barley into malt, by exposure to 
 warmth, moisture, and air, affords an excellent means of 
 studying the phenomena of germination. The barley is 
 first steeped in water for about two days, during which 
 it absorbs moisture, becomes soft, and swells consider- 
 ably. It is then removed to a frame, where it is laid in 
 heaps for about thirty hours; in this state its tempera- 
 ture is raised, and it is disposed to germinate. In order 
 that the heat may be diffused equally through the mass, 
 and that each grain may be brought into contact with the 
 air, the barley is spread out on an airy floor, and fre- 
 quently turned, for about fourteen days, until the ger- 
 mination has advanced to the extent required by the 
 maltster. So soon as the matters contained in the grain 
 have been converted by these processes into saccharine 
 matter, it is necessary to arrest the germination; for, 
 otherwise, the embryos would rapidly absorb the whole 
 of the nutriment thus produced. The grain is, therefore, 
 now removed to the kiln, where it is exposed to a tern-
 
 142 GERMINATION IN MONOCOTYLEDONS. 
 
 perature gradually rising from 100 to 160, for the 
 purpose of drying the grain completely, and of providing 
 against the continuance of germination by destroying the 
 vitality of the embryos. Hence it appears that, during 
 the germination of the barley, its hordein, which is in- 
 soluble, and cannot be applied to the uses of the young 
 plant, is converted into starch, gum, and sugar, the last 
 two of these principles being soluble, highly nutritive, 
 and capable of being absorbed by the embryo. 
 
 217. Germination in Dicotyledons. In the dicotyle- 
 donous seed, the radicle is generally conical and pro- 
 truded, the caulicle cylindrical, and the gemmule placed 
 between the bases of the two cotyledons, which are ap- 
 plied to each other. The entire mass of the seed becomes 
 permeated by moisture and swells. The perisperm or 
 testa bursts; the radicle elongates, and gives out deli- 
 cate ramifications; the gemmule rises and emerges from 
 between the cotyledons ; the caulicle elongates and raises 
 the cotyledons, which separate, expand, become green, 
 and are converted into leaves. When albumen is present 
 in the seed, it softens, and gradually disappears, being 
 absorbed by the embryo. 
 
 218. Germination in Monocotyledons. The embryos 
 of uionocotyledonous plants have a greater uniformity of 
 structure, so that their parts are often not easily distin- 
 guished until germination has commenced. The radi- 
 cular extremity elongates, bursts through its sheath or 
 coleorhiza, and passes downwards. Several radicles 
 generally come off from the lower part of the caulicle, and 
 when these are well developed, the principal radicle dis- 
 appears, so that plants of this kind never have a tapering 
 root, like that of the dicotyledons. The cotyledon en- 
 larges, and is perforated by the gemmule, which emerges 
 from its side or base, enclosed in a sheath, called the 
 coleopt'de. It then perforates this sheath, and elongates.
 
 PROGRESS OF DICOTYLEDONS. 14J 
 
 219. Progress of Dicotyledons. In this state the 
 young plant consists chiefly of cellular tissue, but with 
 vascular fibres forming a kind of cylinder in the centre. 
 This cylinder is the medullary sheath; within it is the 
 pith, and externally the bark. The root imbibes liquid, 
 which passing upwards through the cellular tissue, enters 
 the cotyledons, where it is aerated, and in part passes 
 down through the bark into the root. The plumule 
 gradually ascends, its rudimentary leaves are developed, 
 and soon acquire their full size, when they aerate the 
 sap or mass of imbibed fluid, give out oxygen, and retain 
 carbon. The axis of the plant elongates, other leaves 
 are developed upon it, and a layer of fibres is formed 
 between the pith and the bark. At length, as the season 
 draws to an end, the development of the plant is arrested, 
 and the leaves fall off, while in the axilla of each is formed 
 a bud, composed of a rudimentary branch and leaves. If 
 now examined, the stem will be found composed of a 
 central axis of dry cellular tissue forming the pith, a 
 cylinder of woody tissue, and an outer cylinder of bark. 
 
 220. Continued Progress of Dicotyledons. During the 
 winter the plant remains in a torpid state, but on the 
 return of warm weather vegetation recommences. The 
 sap ascends through the wood of the previous year, the 
 buds gradually expand into branches covered with leaves, 
 by which the fluids are aerated. Each new branch ex- 
 hibits the same phenomena as the stem of the first year, 
 on which a glutinous fluid, called cambium, is found in- 
 terposed between the wood and the bark, in the place of 
 which are ultimately formed a new layer of wood, and 
 another of bark. The leaves fall as before, leaving buds 
 in their axillae. After a period of repose, vegetation is 
 resumed in spring, continued through the summer, and 
 produces the same results. Each successive year, a new 
 layer of wood and a thinner layer of bark are added.
 
 144 PROGRESS OF MONOCOTYLEDONS. 
 
 When the tree has attained the age of puberty, which 
 varies in different species, and in different individuals of 
 the same species, flower-buds are formed, which unfold 
 their parts. The anthers burst, and part of their pollen 
 adheres to the humid stigma. The grains of pollen emit 
 a delicate tube, which, penetrating the stigma and style, 
 transmit the fecundating influence to the ovarium. The 
 ovula being impregnated, the petals and stamens fade, 
 the ovarium enlarges, and the seeds are perfected. At 
 the end of the season, they fall to the ground, either con- 
 tained in the pericarp, or after escaping from it, accord- 
 ing to the species. 
 
 221. Progress of Monocotyledons. -\i has been seen 
 that the enlargement of the stems of dicotyledonous 
 plants takes place by the addition of new matter between 
 the wood and the bark, or near the circumference; whence 
 the plants are named Endogenous, that is, growing at 
 their exterior. But in monocotyledonous plants, the 
 growth is in the inside; whence they are named Endo- 
 genous. When a monocotyledonous plant has germi- 
 nated, and the plumule has shot up, a leaf is emitted 
 from its base. This leaf is succeeded by another, aris- 
 ing from its axilla, and facing it; a third, a fourth, and 
 others follow in succession, until the stem is ready to be 
 produced. The bases of the leaves being upon the same 
 plane, each having been produced from the axilla of the 
 other, without any intervening space, a kind of fleshy 
 stock is produced by their union, consisting of parenchy- 
 matous tissue, with perpendicular fasciculi of vascular 
 and woody tissue, continuous with the veins of the leaves. 
 The whole body is thus a mass of cellular, vascular, and 
 woody tissue, intermingled, without any distinction of 
 pith, medullary sheath, or bark. This mass now elon- 
 gates upwards; leaves are developed from its central part 
 or apex; the former leaves are left forming a circle at
 
 GROWTH OF PLANTS IN GENERAL. 145 
 
 the base; and when the stem has ascended to some 
 height, a new circle, or a spiral series, is formed. The 
 new leaves thrust toward the circumference those which 
 preceded them ; the old leaves decay, their bases remain- 
 ing as part of the stem ; which does not increase in 
 diameter, and has its central parts of softer texture than 
 those toward the exterior, the pressure acting from within, 
 so that the outer parts ultimately assume the appearance 
 of a solid mass of woody fibres, the cellular tissue having 
 become almost obliterated. In this manner, the growth 
 of palms, and many arborescent monocotyledonous plants, 
 takes place. Other plants of that series exhibit differ- 
 ences in their mode of development; the Grasses, for 
 example; but in all, the stem differs from that of dico- 
 tyledonous plants. 
 
 222. Growth of Flowerless Plants. The sporules of 
 these plants appear to germinate from any part of their 
 surface, there being in them no distinction into radicle 
 and plumule. In some, however, roots and stems are 
 formed much in the same manner as in monocotyledonous 
 plants. In Tree Ferns the stem appears to be produced 
 by the bases of the leaves. In the purely cellular tribes, 
 the parts seem to be mere expansions of the cellular 
 tissue; but on this subject nothing very precise can be 
 stated. 
 
 223. Growth of Plants in General. By the absorption 
 of fluids by the roots, a mass of nutritious matter is 
 gradually accumulated in the stem and branches. This 
 fluid passing into the leaves, there undergoes a process 
 by which part of the water is discharged, the remaining 
 part being subjected to the action of the atmosphere; 
 carbonic acid is generated, and then decomposed by the 
 action of light; carbon is fixed in the form of a nutritive 
 material, which is carried into the system ; a further 
 elaboration of this material takes place, after which it is
 
 146 RECAPITULATION. 
 
 applied to the development of all the organs; while, by 
 certain changes, it is also converted into various matters, 
 which are either retained or ejected. The stems and 
 branches, with the leaves and stipules, are gradually de- 
 veloped; the flowers make their appearance, and unfold 
 their parts; the anthers shed their pollen, the application 
 of which to the stigma is followed by the development of 
 the ovules; the fruit is at length matured, and drops to 
 the ground, where the seeds, under favourable circum- 
 stances, become developed into new individuals. The 
 various processes by which the results of vegetation are 
 obtained, may all be resolved into the two functions of 
 Nutrition and Reproduction. But before treating of 
 these, it is necessary to advert to circumstances having 
 reference to the vital power of plants, the properties of 
 vegetable tissues, and the agents by which vegetation is 
 stimulated. 
 
 RECAPITULATION. 
 
 213. What are the principal functions of plants ? From 
 what do plants originate? What is meant by Germination? 
 214. What agents are essential to germination ? Do seeds 
 germinate at a temperature below that of freezing ? What 
 follows when the temperature is too high ? What are the 
 uses of moisture in germination ? Is light beneficial ? Is air 
 necessary ? 215. Within what periods does germination take 
 place in different seeds ? Explain the process of decarboni- 
 zation. 216. Illustrate the phenomena of germination, as they 
 occur in the process of malting barley. 217. Describe the 
 germination of Dicotyledonous Plants. 218. How does ger- 
 mination take place in Monocotyledonous Plants ? 219, 220. 
 Give an account of the progress of growth in Dicotyledons. 
 221. Describe the progress in Monocotyledons. 222. How 
 are Flowerless Plants developed ? 223. Give a short account 
 of the growth of Plants in general.
 
 PROPERTIES OF VEGETABLE TISSUE. 147 
 
 CHAPTER XX. 
 
 VEGETABLE LIFE, PKOPEETIES OF ORGANS, AND 
 STIMULANTS TO VEGETATION. 
 
 224. Vegetable Life. Plants exhibit phenomena simi- 
 lar to those which in animals are considered as charac- 
 teristic of vital agency, agreeing with them in many 
 essential respects, although they differ in others, espe- 
 cially in being destitute of sensibility and voluntary 
 motion. What life really is, whether it be a principle, 
 or influence, or substance, apart from the material fabric 
 by which its phenomena are exhibited, or merely the 
 result of the operation of the elements of nature upon 
 organs adapted for the purpose, seems to be little known. 
 We may therefore speak of life, either as a distinct 
 principle, or as the general result of the operations of 
 an organized body. In reference to this subject, little 
 more can be said of plants than that they are organized 
 and living bodies, having a less complex structure, and 
 exhibiting less remarkable vital actions than animals, 
 between which and mineral bodies they are intermediate, 
 although more intimately allied to the former than to the 
 latter. 
 
 225. Properties of Vegetable Tissue. The cellular and 
 vascular tissues of plants possess various properties in 
 common with animal tissues. Thus, they are extensile, 
 elastic, and absorbent. But they are destitute of the 
 irritability manifested by muscular fibre, and of the sen- 
 sibility dependent upon nervous influence. The processes 
 of secretion and circulation are performed in a different 
 manner in plants and animals. From the manner in 
 which the elementary organs are intermixed in plants,
 
 148 IRRITABILITY. 
 
 and the impossibility of tracing their actions separately, 
 or in succession, our knowledge of their functions is very 
 imperfect. 1. The Cellular Tissue has the property of 
 transmitting fluids in all directions. In many plants 
 there is no other kind of tissue, and yet the sap circulates 
 in all their parts. The pith, the medullary rays, the 
 parenchyma of the leaves, and the greater part of the 
 bark, are composed of it; and in all these parts, at some 
 period, the fluids are diffused and propelled. 2. The 
 Woody Tissue is also pervious to fluids, and gives firm- 
 ness and elasticity to the parts in which it occurs. 
 Wherever vascular tissue exists, it is protected by bundles 
 of woody tissue; and, hence, many parts in which they 
 are united, as the veins and petioles of leaves, are de- 
 scribed as composed of fibro-vascular tissue. 3. The Vas- 
 cular Tissue is partly subservient to the transmission of 
 fluids, and partly of air; at least, the spiral vessels are 
 generally believed to contain the latter. The elasticity 
 of tissue is obviously displayed in many instances, and 
 is more conspicuous when the parts are distended with 
 fluid. The effect of moisture, producing what is called 
 Hygroscopicity, gives rise to motions, which might often 
 be supposed to depend upon irritability. 
 
 226. Irritability, The irritability of plants, if not 
 different from that of animals, is, at least, of a much in- 
 ferior character; and has therefore been by some referred 
 to a property, to which is given the name of Excitability. 
 This property is defined as being that by which the 
 tissue becomes in some manner or degree sensible of the 
 action of external influences, and by which it resists such 
 as would otherwise decompose it. It is a property of 
 life, it is said, to resist destruction, and this property is 
 possessed by plants in common with animals. The irri- 
 tability of animal organs, being inherent in muscular 
 fibre, can have no place in plants; and what is meant by
 
 MOVEMENTS CAUSED BY TOUCH. 149 
 
 the term in Vegetable Physiology is merely the result of 
 movements, which may he referred to other causes. The 
 closing of the leaves and flowers of plants, the shrinking 
 of others when touched, the motions of the leaves of 
 Dioncea, and of the stamens of the Barherry, are of this 
 kind. 
 
 227. Sleep of Plants. Toward the approach of night, 
 in plants which have compound leaves, the leaflets fold 
 together, and the petiole is hent downwards. At the 
 return of day the petiole rises, and the leaflets expand. 
 In some plants, the leaves converge over the flowers; in 
 many, the flowers themselves close, in the absence of the 
 direct light of the sun. The corollas of the Dandelion, 
 Daisy, and many other ComposUce, become erect in 
 gloomy weather, and spread' out in sunshine. The Lu- 
 pine drops its leaflets at dusk. The Convolvulus minor 
 closes its corolla early in the evening, and opens it again 
 as soon as the sun is above the horizon. The Lotus 
 ornithopodioides hides its blossoms beneath its leaves in 
 the evening, so as to escape detection altogether by the 
 most inquiring eye. Phenomena of this nature have 
 been termed the Sleep of plants, and are, no doubt, in 
 some way owing to the action of light, although other 
 causes may also operate. 
 
 228. Movements caused by Touch. The Sensitive 
 Plant, Mimosa pudica, has long been known for the pro- 
 perty possessed by it, in common with other species, of 
 folding up its leaves when touched, or burnt, or other- 
 wise injured. The leaves of this plant are compound, 
 with four pinnate divisions, each partial petiole being 
 furnished with numerous pairs of leaflets. If one of the 
 leaflets be touched, it rises along with its fellow, the 
 leaflets successively bring their upper surfaces together in 
 pairs, and incline toward the summit of the partial petiole; 
 the other pinncB go through the same action, the four par-
 
 150 SPONTANEOUS MOVEMENTS. 
 
 tial petioles come together, and lastly, the petiole itself 
 bends downwards. It appears that the elevation and depres- 
 sion of the leaf is somehow produced hy the tissue in the 
 tumid hasal part of the petiole, for, if its upper portion 
 be cut off, the petiole remains erect, but if its lower por- 
 tion, it remains depressed. Dutrochet considers that 
 the transmission of the excitation is effected by the 
 woody part of the plant, and not by the cortical or 
 medullary parts; for these, he found, might be entirely 
 removed, and irritation above or below the spot would 
 still be propagated beyond it. The excitation extends 
 gradually from the points to which the stimulus is ap- 
 plied; first, the nearest leaves, then the most distant, 
 becoming folded. The excitability is greatly influenced by 
 light and temperature, as well as by the pressure or ab- 
 sence of atmospheric air. Both the excitability and the 
 mobility of the Mimosa are lost after a few days, when 
 the plant is deprived of light; the susceptibility of ex- 
 ternal stimulus being lost before the movements of sleep 
 and waking cease. Variations in the temperature of the 
 atmosphere also cause the quickness of the transmission 
 of the excitation from one part of the plant to others to 
 vary; and at 471 Fah. no motions could be excited. 
 
 229. Spontaneous Movements. Some plants exhibit 
 motions which have been called Spontaneous, merely 
 because not excited by touch or external violence. Of 
 this kind are those of the two lateral leaflets of the ter- 
 nate leaves of Hedysarum gyrans, which are in continual 
 motion, day and night, especially in warm weather. 
 When the fruit of Momordica elaterium has attained 
 maturity, its peduncle is suddenly expelled, along with 
 the seeds, and the mucilaginous fluid by which they are 
 surrounded. But, according to Dutrochet, this pheno- 
 menon is caused by a circumstance of general occurrence 
 in plants, to which he has given the name of Endosmose.
 
 ACTION OF POISONS. 151 
 
 230. Endosmose. Although vegetable and animal 
 membranes, when examined with the microscope, are 
 not observed to have any pores, but appear perfectly con- 
 tinuous, it is found that liquids readily pass through them. 
 If mucilage, or gum dissolved in water, be enclosed in 
 a piece of bladder, which is then immersed in water, a 
 portion of the gum will pass through the bladder into the 
 water, of which a portion will, on the other hand, pass 
 into the bladder. If the experiment be reversed, so will 
 the result. It is the same with milk, or any other liquid. 
 The general law, according to M. Dutrochet, is, that 
 when two fluids of unequal density are separated by a 
 membrane, the denser fluid will attract the less dense. 
 When the attraction is from without inwards, he names 
 the action Endosmose; when from within outwards, Exos- 
 mose. The transmission he considers as caused by gal- 
 vanic agency. There can be no doubt that many of the 
 phenomena of vegetation are dependent upon this pro- 
 perty of membrane; and some are of opinion, that it is 
 the principal cause of the motion of the fluids of plants. 
 
 231. Action of Poisons. As a proof of the existence 
 of sensibility in plants, has been adduced the action of 
 many substances, which prove destructive to life, without 
 corroding or decomposing the tissue. M. Marcet, of 
 Geneva, found, that not only oxide of arsenic, corrosive 
 sublimate, preparations of lead, tin, and copper, potash, 
 and other acrid poisons, on being absorbed by the roots, 
 produce death; but also solutions of opium, nux vomica, 
 belladonna, prussic acid, and other narcotic poisons, 
 which are understood to act upon the nervous system in 
 animals. From the experiments made, he infers, that 
 metallic poisons act on plants nearly as on animals, alter- 
 ing and destroying the tissue by their corrosive powers; 
 and that vegetable poisons, especially those which cause 
 death in animals by their action upon the nervous sys-
 
 152 ACTION OF LIGHT. 
 
 tern, destroy life in plants without altering the tissue. 
 Similar results have been obtained by M. Macaire, and 
 others. Yet nothing analogous to a nervous system, 
 even of the kind observed in the lower series of animals, 
 has been observed in plants. 
 
 232. Stimulants of Vegetation. Whatever may be the 
 kind or degree of sensibility possessed by plants, or 
 whatever the peculiarities of the intimate structure of 
 their organs, we know that their vital power languishes 
 or remains dormant, or, on the other hand, manifests 
 itself with greater energy, according to the varied in- 
 fluence of external agents. Thus, a seed will not ger- 
 minate unless supplied with moisture and atmospheric 
 air, and submitted to a moderate temperature ; after a 
 long drought, plants become shrivelled and languid; and, 
 when deluged with continued rains, shoot out long but 
 feeble stems, or, if they perfect the branches and leaves, 
 bear little fruit. The stimulants to vegetation are light, 
 heat, electricity, air, and water. 
 
 233. Action of Light. When a plant is made to 
 vegetate in a cellar or other dark place, it remains white; 
 and when brought into the light, soon acquires its natu- 
 ral green colour. The practice of blanching Celery and 
 Kale, by covering them from the light, is familiar to 
 every one. Light being essential to the healthy develop- 
 ment of all the parts of plants, not only the stems, but 
 the leaves and flowers, manifest a tendency to direct 
 themselves toward it. In the open air, the upper sur- 
 face of leaves is turned toward the sky, and in a hot- 
 house all the plants present the fronts of their leaves. 
 Many flowers are equally sensible to light, and especially 
 those of the Composite, such as the Dandelion, Daisy, 
 and Sunflower, which are observed in some degree to turn 
 themselves toward the sun. What is called the Sleep of 
 Plants, I 227, or the folding up and drooping of their
 
 ACTION OF HEAT. 153 
 
 leaves at night, appears to depend chiefly upon the dimi- 
 nution of light; for it has been found, that some plants 
 will unfold their leaves under the action of lamp-light. 
 The colours of the flowers, the odorous secretions of 
 plants, and the firmness of their texture, also depend, in 
 a great measure, upon the supply of light. 
 
 234. Action of Heat. The great influence which 
 temperature exercises on the development and functions 
 of plants, is abundantly obvious. When other circum- 
 stances are equal, the vegetation is much more vigorous 
 in warm than in cold climates. In countries where the 
 temperature is below the freezing point, plants cannot 
 exist; and during winter, when the same takes place, no 
 nourishment can be obtained by the roots, as the water 
 in the soil is frozen. It does not appear that any natu- 
 ral degree of heat is injurious to vegetation, provided 
 moisture be supplied in sufficient abundance. But all 
 plants are not equally adapted for bearing the same de- 
 grees of heat or cold. Some grow within the influence 
 of hot springs, in which the thermometer stands at 
 200 ; while others are capable of resisting the severity 
 of winter in climates where the temperature falls to 30 
 or more. Most tropical plants are killed by a freezing 
 degree of cold; and many introduced into our climates 
 require an artificial temperature. On the other hand, 
 many of the plants of cold climates do not thrive in 
 tropical regions. Particular species thus have a peculiar 
 constitution ; and it has been found, that some have a 
 higher temperature than others. It is a general law in 
 our climates, that the temperature of trees is higher in 
 winter than the average temperature of the air, and lower 
 in summer ; which may be accounted for, in a great 
 measure, by their roots penetrating to a depth where the 
 soil is always warmer than the air in winter, and colder 
 in summer. It has been observed that some plants, at
 
 154 ACTION OF AIR AND WATER. 
 
 the period of flowering, emit a considerable degree of 
 heat. This has been observed, particularly in the 
 Arums, Senebier having noticed that the temperature 
 of the spadix of Arum macidatum was 7 higher than 
 that of the surrounding air ; and M. Hubert, on placing 
 a thermometer in the centre of twelve spadices of Arum 
 cordifolium, in the Isle of France, having found the 
 temperature to be 121, while that of the air was 
 only 66. 
 
 235. Action of Electricity. It has been observed, 
 that plants grow with increased vigour during electrical 
 weather ; but in this case, the high temperature, and 
 abundant supply of moisture, which accompany thunder- 
 storms, may of themselves account for the phenomenon. 
 It has long been an opinion, that some trees are more 
 liable to be struck by lightning than others ; and this is 
 probable enough, although it does not appear that the 
 subject has undergone any strict examination. All 
 trees, however, by the numerous points which their 
 twigs and leaves present, are well adapted for silently 
 drawing electricity from the clouds. 
 
 236. Action of Air and Water. Plants, like animals, 
 when deprived of air, perish. It is by the action of this 
 fluid upon their elementary organs and juices, that 
 materials are procured for the development of their 
 parts, as will be subsequently explained. Atmospheri- 
 cal currents, by agitating the stems and foliage, promote 
 the circulation of the sap ; but when their velocity is 
 great, they frequently prove injurious, by breaking or 
 bruising the organs. Water, being the vehicle of all the 
 nutritious matters absorbed by plants, is essential to their 
 existence. When it is supplied in diminished quantity, 
 they become stunted ; and when furnished in too great 
 profusion, they acquire an inordinate development, but 
 are unable to discharge all their functions in an efficient
 
 RECAPITULATION. 155 
 
 manner. Continued or heavy rains are injurious to the 
 impregnation of the ovules, by washing away the pollen 
 before it has exerted its influence. But, as in the sub- 
 sequent chapters, these and other circumstances will be 
 explained, it is inexpedient to offer any further observa- 
 tions on the action of water. 
 
 We now proceed to the consideration of the functions 
 of Nutrition and Reproduction. 
 
 RECAPITULATION. 
 
 224. Have plants many properties in common with ani- 
 mals ? 225. What are the properties of the tissues of plants ? 
 Do fluids circulate in the cellular tissue ? What properties 
 have the woody and the vascular tissues ? 226. Are plants 
 possessed of Irritability ? Does it differ from that of animals ? 
 What is Excitability ? 227. What is meant by the sleep of 
 plants ? Illustrate this phenomenon in several plants. 228. 
 What plant exhibits peculiar motions on being touched ? 229. 
 Have plants spontaneous motions ? 230. What are the phe- 
 nomena designated by the terms Endosmose and Exosmose ? 
 Is it probable that they operate in plants ? 231. Are plants 
 acted upon by poisons, in the same manner as animals ? As 
 vegetable poisons act upon the nervous system in animals, is 
 it proved, by the similarity of their action in plants, that the 
 latter have a nervous system ? Have nerves been detected 
 in plants ? 232. Mention the principal stimulants to vege- 
 tation. 233. Give some account of the action of Light upon 
 plants. 234. What effect has Electricity upon them? 235. 
 State some particulars relative to the influence of Heat. What 
 plants have been observed to emit heat ? 236. What effects 
 are produced on plants by the action of air and water ?
 
 156 FUNCTION OF NUTRITION. 
 
 CHAPTER XXI. 
 
 FUNCTION OF NUTRITION. 
 
 ABSORPTION. THE ASCENDING SAP, OB LYMPH. PROGRES- 
 SION OF THE LYMPH. EXHALATION. RESPIRATION. 
 
 237. Function of Nutrition. We have seen that 
 plants are furnished with roots, stems, leaves, flowers, 
 and fruits, together with various subordinate parts ; and 
 it has been stated, 6, that these organs may be phy- 
 siologically disposed into two classes; the root, stem, 
 and leaves being subservient to the function of Nutrition, 
 the flower and fruit to that of Reproduction. 
 
 When the young plant is developed in consequence of 
 germination, it extracts from the soil or the air the 
 materials necessary for its further growth, and assimi- 
 lates them, or transforms them into its own substance. 
 This great function, which characterizes the second 
 epoch in the life of the plant, is known by the name of 
 NUTRITION. It includes several subordinate functions, 
 which establish as many distinct periods. The plant 
 extracts its food from the ground by means of its roots ; 
 the nutritious fluid or sap is then conveyed through the 
 stem to the leaves ; there the superfluous water is ex- 
 pelled ; the remaining part is in the same organs sub- 
 mitted to the action of the air, part of which combines 
 with it ; the sap thus altered, descends from the leaves 
 to the roots, and is applied to the nourishment of all the 
 organs of the plant ; lastly, the portion of the sap not 
 required for this purpose is converted into substances, 
 intended for particular uses, or to be ejected from the
 
 ABSORPTION. 157 
 
 plant. These subordinate functions or processes may be 
 designated: 
 
 1. Absorption, or imbibition of liquid. 
 
 2. Progression, or ascent of the crude sap. 
 
 3. Exhalation, or transpiration of liquid. 
 
 4. Respiration of oxygen of carbonic acid. 
 
 5. Retrogression, or descent of the elaborated sap. 
 
 6. Increase, or growth of the plant. 
 
 7. Secretion of retained or rejected matters. 
 
 238. Absorption. It was stated, \ 32, that the Roots, 
 besides fixing the plant in a commodious situation, ex- 
 tract from the soil, by the spongy extremities of their 
 fibrils or radicles, the substances intended for the 
 nourishment of the plant. The nutritious particles must 
 be dissolved or suspended in water before they can be 
 absorbed. Now, all vegetable tissues have the property 
 of attracting water until they are in equilibrium as to 
 humidity with the surrounding bodies. This action of 
 vegetables is known by the name of Absorption, or Suc- 
 tion. The leaves absorb moisture from the atmosphere, 
 chiefly by their lower surface, and all the green parts of 
 plants possess the same faculty ; but it is chiefly by the 
 roots that this function is performed. These organs are 
 especially adapted for the purpose, by having the ex- 
 tremities of their fibrils destitute of cuticle ; and, as the 
 ground is never entirely deprived of moisture, and is 
 often profusely supplied with it, a constant fund of nu- 
 tritious matter is afforded. Some plants, however, vege- 
 tate luxuriantly in an arid soil, and are furnished with 
 very small roots. They must, therefore, extract their 
 nourishment almost exclusively from the atmosphere, 
 which they absorb by their whole surface. This is what 
 is specially observed in succulent plants, or those having 
 thick and fleshy leaves and stems ; as Cactus, House- 
 leek, and Stonecrop.
 
 158 FOOD OF PLANTS. 
 
 239. Food of Plants. The food of plants consists of 
 carbon, hydrogen, oxygen, nitrogen, and certain earthy 
 particles or ashes. 
 
 (1.) The carbon of plants is mainly derived from car- 
 bonic acid, taken either from that of the air, or from that 
 which is evolved by the spontaneous decomposition of 
 manure in contact with the roots. But it is from the 
 former source especially that plants derive their carbon, 
 a statement which cannot be doubted, when we reflect 
 upon tbe enormous quantity of carbon whicb has been 
 fixed by trees of long growth, compared with the very 
 limited extent of their roots. The soil into which the 
 acorn fell, a hundred years ago, did not contain a 
 millionth part of the carbon now deposited in the oak : 
 the atmosphere has furnished all the rest. It was found 
 by M. Boussingault, that peas sown in sand, watered 
 with distilled water, and fed by the air alone, derived 
 from this air all the carbon necessary for their develop- 
 ment, flowering, and fructification ; and that the leaves 
 of a vine, enclosed in a glass vessel, absorbed the whole 
 of the carbonic acid from a stream of air transmitted 
 through the vessel, however rapid the transmission. 
 
 (2.) The hydrogen of plants is obtained by the decom- 
 position of water, as carbon is obtained by the decom- 
 position of carbonic acid. This follows from the experi- 
 ment of the vegetation of peas in close vessels. The fact 
 is proclaimed more decisively by the production of the fat 
 and volatile oils which abound in various parts of plants, 
 and are known to be rich in hydrogen. This can be 
 derived only from water, inasmuch as plants have no 
 other hydrogenous compound to feed on but water. 
 
 (3.) The nitrogen of plants is procured from the atmo- 
 sphere, or from manures added to the soil. In either 
 case it seems probable that the nitrogen enters the plant 
 only in the form of ammonia or of nitric acid. The experi-
 
 
 CAUSES AND STIMULANTS OP ABSORPTION. 159 
 
 ments of M. Boussingault have shown that certain plants, 
 as Jerusalem artichoke, abstract large quantities of nitro- 
 gen from the air ; and that others, on the contrary, as 
 wheat, depend upon manure for the supply of this element 
 of nutrition. " What an important distinction," says 
 M. Boussingault, " is this for agriculture. Is it not 
 obvious that we must begin by raising plants which assi- 
 milate the nitrogen of the atmosphere, with these feed 
 animals which shall furnish us with manure, and then 
 apply this to the culture of those plants which are de- 
 pendent on manure for their nitrogen ?" 
 
 (4.) The ashes found in plants are obtained through the 
 medium of water, an immense quantity of which passes 
 through a plant during the term of its existence. This 
 water evaporates from the surface of the leaves, and neces- 
 sarily deposits, as its residue, the salts which it held in 
 solution. These salts constitute the ashes of plants 
 products evidently derived from the soil, and restored to 
 it again by plants after their death. The forms in which 
 these mineral products are deposited in the tissues of 
 plants are numerous ; one of the most frequent and 
 abundant forms is that of pectinate lime, which occurs 
 in the woody tissues of most plants. Other matters are 
 the phosphate of magnesia, common salt, nitre, the salts 
 of iron and copper, <kc. 
 
 240. Causes and Stimulants of Absorption. The juices 
 existing in the plant at germination, and in the earliest 
 stage of its subsequent development, being probably 
 denser than the surrounding liquid or aerial media, the 
 absorption of these media may perhaps be accounted for 
 by endosmosis. If the tissue had the power of remov- 
 ing the fluids, and causing them to ascend as fast as they 
 are absorbed by the spongioles, we might, as Professor 
 Henslow remarks, imagine the possibility of a supply 
 being kept up by the mere hygroscopic property of the
 
 160 PROGRESSION OF THE SAP. 
 
 tissue, much in the same way as the capillary action of 
 the wick of a candle maintains a constant supply of wax 
 to the flame by which it is consumed. The action of the 
 spongioles is indirectly stimulated hy the atmospheric 
 heat and light which cause the removal of a large por- 
 tion of the general mass of fluid hy exhalation ; hut light 
 is not a direct stimulant, for plants ahsorh in the dark, 
 and the roots are generally deeply buried in the soil. It 
 does not appear that many substances, which stimulate 
 the organs of animals, have any such effect upon the 
 radicles of plants, which as readily absorb inert as acrid, 
 and noxious as useful, matters, provided they be suffi- 
 ciently comminuted or dissolved. It might appear, from 
 the effects of manure, that it must stimulate the roots, 
 otherwise it might seem impossible to account for the 
 rapid growth to which it gives rise. 
 
 241. The Lymph. The mass of fluid imbibed by the 
 root and other absorbent surfaces is named the Ascending 
 Sap or Lymph. In its most simple state, it is found to 
 be composed of water, with a little mucilage or sugar. 
 As the two latter substances do not exist in the soil, it 
 must be inferred that they have been produced within 
 the plant by some chemical action upon the imbibed 
 liquid. Of the many other substances found in plants, 
 although in very small quantity, as flint, some suppose 
 them to be products of the vital action of the plant itself, 
 while others, with more probability, maintain that they 
 must have been absorbed from the soil. In the first 
 state of the sap, the substances which it holds in solution 
 or suspension bear an extremely small proportion to the 
 mass of water. 
 
 242. Progression of the Sap. The aqueous fluid 
 absorbed by the root, and which is more abundant than 
 that imbibed by the other organs, has a constant ten- 
 dency to ascend towards the leaves. Hales removed
 
 PROGRESSION OF THE SAP. 161 
 
 the soil from the root of a pear-tree and cut the root 
 across ; he then introduced the portion of the root 
 attached to the tree into a tube filled with water, 
 hermetically closed above, and dipping below into a basin 
 of mercury ; the water hi the tube was absorbed by the 
 section of the root, and this with such force that the 
 mercury rose eight inches in the tube, to replace the 
 water. In the stems of dicotyledonous trees, it has been 
 ascertained that the course of the sap is through the 
 woody tissue, and especially the alburnum or outer layers 
 of softer wood. Its ascent takes place, as above stated, 
 with great force ; but there are circumstances in which 
 its progress is accelerated, and its quantity increased, in 
 a very perceptible degree. In general, heat increases 
 its velocity, while cold diminishes it. In perennial 
 plants, the sap is observed to be greatly increased at the 
 commencement of spring, before the leaves have been 
 developed. At this period, trees and shrubs absorb a 
 great quantity of water, which mingles with the nutri- 
 tious fluid with which all the parts are then gorged. 
 Another period at which the sap accumulates is in 
 August. It is to be remarked that the spring sap cor- 
 responds to the period at which the buds of the preceding 
 year begin to unfold, and the August sap to that at 
 which the buds of the ensuing year begin to be formed ; 
 as if these buds, whose development is due to the afflux 
 of sap, attracted that nutritious fluid to them, and thus 
 accelerated its ascent. If a tree be felled in spring, 
 the sap is found to issue most abundantly from the cen- 
 tral parts ; but it usually or often pervades all the woody 
 parts, and may be obtained in great quantity, in certain 
 trees, as the Birch and Sycamore, by making an incision 
 into the outer layers of the wood. It has not been 
 ascertained whether the sap in its progress undergoes 
 any alteration, analogous to digestion in animals ; but
 
 162 CHANNELS OF THE ASCENDING SAP. 
 
 when a tree is tapped at different heights in spring, the 
 fluid that exudes from the lower orifice is found to be 
 clearer than that from the upper. This, however, may 
 he owing to the admixture of the newly-absorbed liquid 
 with the juices previously elaborated, and deposited in 
 the wood. When it has arrived at the extremities of the 
 branches, it enters the leaves, where it undergoes a change 
 which renders it fit for becoming assimilated. 
 
 243. Channels of the Ascending Sap. There is con- 
 siderable difference of opinion respecting the channels 
 through which the sap is conveyed. Some observers 
 suppose it to be propelled through the ducts or vessels, 
 others through the intercellular or intervascular pas- 
 sages, while others think it passes from cell to cell by 
 transfusion. The cause of this discrepancy is the ex- 
 treme attenuation of the vesicles and tubes of the tissue 
 of plants, and the difficulty of being convinced whether 
 the fluids are without or within the vessels, the micro- 
 scope not affording a sufficiently distinct view of the parts. 
 Whether by the intercellular passages or by transfusion 
 from one cell or vessel to another, the sap, in its ascent, 
 tends to a lateral extension, as is indicated by its reach- 
 ing the summit of a tree in which deep incisions have 
 been made at intervals on different sides. It appears, 
 from the experiments of Mr. Rainey, that " the crude 
 sap ascends along a tissue which chiefly exists between 
 the cells, but which enters also into the structure of the 
 more solid and permanent parts of a plant." The loca- 
 lity of this intercellular tissue may be seen by referring 
 to Fig. 3, p. 9 ; in which the dark parts between the 
 cells at a and h represent this tissue. "The quantity 
 of intercellular tissue contained in different parts of the 
 same plant varies very considerably ; there is scarcely 
 any between the cells of the pith, or between those 
 containing the starch in cotyledons, but it exists abun-
 
 CAUSES OP PROGRESSION. 163 
 
 dantly between all the cells of the wood, and also be- 
 tween some of the cells of the bark. The intercellular 
 tissue, besides serving for the ascent of the sap, will, 
 from its universal existence and general contiguity, be 
 the means also of its lateral diffusion. The medullary 
 rays are composed of cells longest generally in their 
 horizontal diameter, and, like the cells of wood in other 
 parts, surrounded by intercellular tissues." (Experi- 
 mental Inquiry.} 
 
 244. Causes of Progression. The rapidity with which 
 the sap ascends is evident from the great loss which 
 plants often undergo from exhalation, and which must 
 be made up by radicular absorption. A young leaf of 
 a vine perspires so profusely in a hot day, that a glass 
 placed near its lower surface is presently covered with 
 vapour, which soon trickles down in streams. Hales 
 found a sun-flower to lose one pound four ounces, and a 
 cabbage one pound three ounces, a-day, by perspiration. 
 This exhalation itself may be one cause of the ascent of 
 the sap, although it may also be propelled by a power 
 residing in the extremities of the roots. De Candolle 
 supposes it to be conveyed along the intercellular pas- 
 sages by an alternate contraction and dilatation of the 
 cells themselves ; but of this it appears there is no proof. 
 Hales, having cut off the stem of a vine in spring, and 
 luted a bent tube to the top of the stump, found, by in- 
 troducing mercury at the open end, that the force of the 
 rising sap equalled the pressure of an atmosphere and a 
 half. If a piece of bladder be tied over the surface of 
 such a stump, it soon becomes distended, and ultimately 
 bursts. Tbese phenomena certainly indicate a powerful 
 force, for which endosmosis and capillary attraction seem 
 hardly sufficient to account. Du Petit Thouars, however, 
 explains it on that principle. In spring, he says, when 
 vegetation commences, the extremities of the branches
 
 164 EXHALATION OF LIQUID. 
 
 and the buds begin to swell ; for the supply of these 
 buds a quantity of sap is attracted from the neighbour- 
 ing tissue, which is again instantly filled from that 
 beneath it ; and thus the whole mass of fluid is set in 
 motion. He thus thinks that the expansion of the buds 
 and leaves is not the effect, but the cause, of the ascent 
 of the sap. 
 
 245. Exhalation or Transpiration of Liquid. The 
 sap, on arriving in the leaves, undergoes a change, of 
 which the first stage is a diminution of its mass by the 
 exhalation of a great part of the water which served as 
 the vehicle of the nutritious substances contained in it. 
 This is evident from the mere observation of fading 
 plants, and from the deposition of moisture on the inner 
 surface of a bell-glass, containing plants, and exposed to 
 the sun ; so much as two spoonfuls of water has been 
 collected from the exhalation of a leafy branch in the 
 period of two hours. The quantity of moisture exhaled 
 has been measured by weighing the plant at different 
 periods, and reckoning the amount of water supplied to 
 it. In this way, Hales found that a sunflower lost 20 
 ounces, and a cabbage 19 ounces of water in the course 
 of the day. He considered that, surface for surface, 
 the plant exhales 17 times more than man. When the 
 transpiration is moderate, the water, on arriving at the 
 surface of the leaf, is entirely evaporated, and the process 
 resembles that of insensible perspiration in animals ; but 
 when too large a quantity of fluid arrives at the surface, 
 its evaporation cannot take place at once, and we then 
 see it oozing in the form of extremely small drops at the 
 tip of the leaf, and especially at the extremities of the 
 nerves; several of these limpid drops often unite, and 
 then acquire a considerable size. In this manner a large 
 quantity of clear water is often seen collected on the 
 leaves of the cabbage, poppy, and other plants. This
 
 STIMULANTS TO EXHALATION. 165 
 
 water is not produced by dew, as it forms when all com- 
 munication of the plant with the amhient air is inter- 
 cepted by covering it with a glass, and with the surface 
 of the ground by applying over the latter a leaden plate 
 having a hole in the middle for the passage of the stem. 
 It having been found that those plants exhale most which 
 have the greatest number of stomata, and that those 
 surfaces which are destitute of stomata produce little 
 effect beyond what may be accounted for by ordinary 
 evaporation, it appears evident that the stomata are the 
 exhalant organs, and exhalation is more abundant on the 
 under surfaces of leaves, because there the stomata are 
 generally most numerous. 
 
 246. Stimulants to Exhalation. If we distinguish be- 
 tween ordinary evaporation, which operates alike on dead 
 and living plants, and exhalation by the etomata, we find 
 ourselves unable to account satisfactorily for the latter, 
 as the manner in which the stomata act is unknown. 
 When a plant is placed in a dark room, its exhalation 
 ceases, and when restored to the light, returns. Hence 
 it is inferred that light is its principal stimulant. Heat 
 also appears to aifect it ; at least evaporation is thereby 
 greatly increased. Many succulent plants have so few 
 stomata, that they may be preserved for weeks out of 
 the ground, without dying ; on the other hand, submersed 
 plants, which are destitute of epidermis, dry up rapidly 
 on being exposed to the air. The water exhaled by the 
 leaves is so pure that scarcely any traces of foreign 
 matter are found in it. It is calculated that in general 
 about two-thirds of the fluid absorbed by the roots are 
 exhaled. The remaining portion, thickened and retain- 
 ing the various substances originally dissolved in it, 
 undergoes a further change. 
 
 247. Respiration. By this term is denoted the func- 
 tion by which the atmospheric air and the fluids con-
 
 166 COLOUR OF PLANTS. 
 
 tained in the vegetable organs mutually modify each 
 other. 1 . During the day, the slight portion of carbonic 
 acid contained in the atmosphere is decomposed by the 
 green parts of plants ; the carbon is fixed -within the 
 plant, the oxygen remains in the air. Carbonic acid 
 exists also in the liquid absorbed by the root ; this quan- 
 tity is also decomposed by the green parts, the carbon 
 being, as in the other case, fixed in the plant, while the 
 oxygen is restored to the air. This is sometimes termed 
 the function of digestion, or the assimilating power of 
 plants. 2. During the night plants absorb or inspire, 
 by their green parts, a certain quantity of oxygen from 
 the atmosphere ; this gas appears to combine with the 
 carbon contained in the sap, forming carbonic acid, 
 which is afterwards decomposed by the action of solar 
 light. Plants also, at all times, especially during the 
 night, part with carbonic acid in small quantities. This 
 absorption of oxygen and evolution of carbonic acid con- 
 stitute the function of respiration, properly so called. 
 3. The healthful relation of plants to the atmosphere 
 appears, therefore, to consist in the alternate decomposi- 
 tion and recomposition of carbonic acid ; and its result 
 is the increase of bulk in the plant, by the assimilation 
 or digestion of carbon. 4. It follows also that plants 
 are the great purifiers of the atmosphere, since they con- 
 sume the products of animal respiration and of all 
 organic putrefaction, and convert them into matter 
 adapted to the use of man. It has been found that 
 plants purify the air much more by their assimilating, 
 than they vitiate it by their respiratory, function. 
 
 248. Colour of Plants. The green colour of plants 
 appears to result from the decomposition of carbonic 
 acid, and the fixation of carbon ; and as this effect takes 
 place only through the action of light, we see how great 
 an influence that agent exercises upon the coloration and
 
 EFFECT OF RESPIRATION. 167 
 
 nutrition of plants. As already mentioned, vegetables 
 which grow in darkness, are blanched, slender, and more 
 watery and elongated than they would be, were they ex- 
 posed to the sun's light. The green colour of plants, 
 and indeed all colours, depend upon the presence of 
 minute granules in the vesicles of the cellular tissue. 
 The granules that produce the green tints are named 
 Chromule, and are composed chiefly or entirely of car- 
 bon. The parts of plants which are coloured otherwise 
 than green, do not assimilate the oxygen of the air, but 
 whether by day or by night, this oxygen combines with 
 a part of their carbon which is superabundant, and thus 
 reproduces carbonic acid. 
 
 249. Effect of Respiration on the Atmosphere. Plants 
 vitiate the air around them, because their green parts 
 inspire by night a certain quantity of oxygen, which 
 they do not entirely restore by day, and because the parts 
 which are not green form carbonic acid at the expense 
 of their proper substance. On the other hand, plants 
 purify the air by decomposing the carbonic acid formed 
 within them, and that which they absorb dissolved in 
 air or water. The ultimate effect of vegetation plainly 
 consisting in an increase of the mass of carbon fixed in 
 plants ; and, carbon arriving in them only through the 
 decomposition of the carbonic acid of the air, it is clear 
 that vegetables, considered in a general sense, tend to 
 diminish the quantity of carbonic acid in the atmosphere, 
 and to increase that of oxygen. But the respiration of 
 animals and combustion tending to produce just the con- 
 trary effect, the general stability of the constitution of 
 the atmosphere is not perceptibly disturbed. 
 
 The sap altered by respiration in the leaves and other 
 green parts, now descends into the stem and root, and 
 is rendered subservient to the development of all the 
 organs.
 
 168 RECAPITULATION. 
 
 RECAPITULATION. 
 
 237. What are the two principal functions of plants, and 
 the organs by which they are performed ? Give a general 
 account of the function of Nutrition, and enumerate its 
 various stages. 238. What is meant by Absorption? By 
 what organ is it chiefly performed ? What other parts of 
 plants imbibe moisture ? How are succulent plants, which 
 grow in dry sand, nourished ? 239. Of what substances does 
 the food of plants consist ? From what sources is the carbon 
 derived? What experiments have been instituted on this 
 subject ? Whence is the hydrogen, and the nitrogen of 
 plants obtained ? What minerals are found in the tissues 
 of plants ? 240. How may endosmose act in producing 
 absorption ? What effects have heat and light upon absorp- 
 tion ? 241. What is the Sap ? Of what is it composed ? 
 How are the various substances found in it supposed to be 
 introduced or generated? 242. What becomes of the fluid 
 absorbed by the roots ? At what periods of the year is the 
 sap most abundant ? Is there any difference in the quality of 
 sap obtained at different heights in trees ? What becomes 
 of the ascending sap ? 243. Through what channels is the 
 sap conveyed ? 244. What are the causes of its progression ? 
 245. What change is first undergone by the sap on its 
 entering the leaves ? What were the results of Hales's experi- 
 ments ? When the transmission of sap into the leaves is very 
 rapid, what happens ? How is it proved that the drops on 
 leaves are not produced by dew ? How does it appear that 
 the stomata are the exhalant organs ? 246. What circum- 
 stances are favourable to exhalation? Are succulent plants 
 more readily dried ? What proportion of the sap is exhaled? 
 247. What is meant by respiration ? Explain the assimi- 
 lating power of plants, which is in operation during the day. 
 What alternate economy occurs during the night. Do plants 
 give off carbonic acid during the night as well as during the 
 day ? How are plants increased in bulk ? Explain the 
 healthful action of plants upon the atmosphere. 248. How
 
 NUTRITION. 169 
 
 is the green colour of plants produced ? What is Chromule ? 
 249. How does vegetable respiration affect the state of the 
 air ? What effect has the respiration of animals upon it ? 
 
 CHAPTER XXII. 
 
 NUTRITION (Continued.) 
 
 THE ELABORATED OR DESCENDING SAP. ITS PROGRESS DOWN- 
 WARDS. VEGETABLE SECRETIONS. ASSIMILATION. 
 
 250. Descent of the Elaborated Sap. The crude, or 
 ascending sap, having expended two-thirds of its amount 
 by aqueous transpiration, and a slight proportion of its 
 gases by respiration, is converted into a fluid capable of 
 being assimilated by the various parts of the plant, and 
 consequently of directly affording them nourishment. 
 It then forms what has been called the Nutritious Juice, 
 Proper Juice, True Sap, or Descending Sap. In this 
 state it contains a large proportion of gum, sugar, or 
 fecula, and is further submitted to modifications resulting 
 in the formation of various substances, either to be 
 retained or separated as useless. Owing to the manner 
 in which the juices are intermixed, and on account of 
 the great number of vegetable products contained in 
 them, it seems impossible to determine the true nature 
 of the elaborated sap. All these products are composed 
 merely of different modifications of the same elements, 
 namely, carbon, oxygen, and hydrogen ; but the fluids 
 of different species of plants present great differences 
 in their palpable qualities ; so that no particular modifi- 
 cation can be assumed as characterizing the general sap, 
 analogous to the blood in animals. In some plants the
 
 170 DESCENT OF THE SAP. 
 
 sap is a white and milky juice, in others yellowish, in 
 many limpid ; and its properties are equally various. 
 
 251. Descent of tlie Sap. The principal movement 
 of the elaborated sap is in the inverse direction of that 
 of the lymph or fluid absorbed by the roots. If a tight 
 ligature be applied to the trunk of a dicotyledonous tree, 
 or a ring of bark removed from it, the nutritious juices 
 being unable to descend, accumulate above the ligature 
 or ring, and there form a circular swelling, which be- 
 comes more and more prominent. It is further remarked, 
 that the part of the trunk situated beneath the ligature 
 ceases to grow, and that no new woody layer is added to 
 those already existing, because the nutritious fluid is 
 unable to reach it. This fact therefore proves, that it 
 is to the descending sap that the growth of the plant is 
 due. It circulates chiefly in the parts of the stem in 
 which new layers are formed, or along the bark and 
 alburnum. It covers the inner surface of the former, 
 and the outer surface of the latter, with a fluid, which 
 becomes more and more viscid, and then takes the name 
 of Cambium. Presently traces of organization appear 
 in this fluid, and there are formed in it new cellules and 
 fibres, which gradually acquire consistence. This, as 
 has been stated, is the mode of growth in the trees of 
 our climates ; but it does not appear that anything is 
 known with precision regarding the descending sap in 
 the stems of monocotyledonous trees. 
 
 252. If the channel of the ascending sap has been a 
 matter of much uncertainty, that of the descending sap 
 has occasioned at least equal perplexity. Mr. Rainey 
 observes "Now the only parts which connect the leaves 
 of the exogenous plant with its branches, are cells, 
 vessels, and intercellular tissue ; and it has been shown 
 that the descending sap does not pass along the last 
 of these, that is, the intercellular tissue ; it must, there-
 
 PECULIAR OR LOCAL MOVEMENTS. 171 
 
 fore, be conducted either by the cells or by the vessels. 
 The cells being distinct one from another, surrounded 
 by intercellular tissue, and having no openings of com- 
 munication one with another, can scarcely be supposed 
 to serve as conductors of a fluid ; . . . and therefore 
 the function of conducting the elaborated sap may fairly 
 be inferred to be performed by vessels. Moreover, 
 vessels are continuous passages extending from the leaves 
 all along the branches and stem down into the roots, and 
 have large and extremely well defined openings of com- 
 munication one urith another, and therefore possess all 
 the necessary anatomical characters of tubes designed 
 for the transmission of a fluid." (Experimental Inquiry.) 
 It remains only that we notice the elaboration which 
 takes place in the root, and the ascent of the elaborated 
 sap, in the early part of the year, before the leaves 
 appear. This process is analogous to that of germina- 
 tion ; as the starch deposited in the seed becomes con- 
 verted into sugar and gum for the nutrition of the 
 embryo, so the starch deposited in the root while the 
 leaves were in active operation, probably undergoes a 
 similar change, in the early part of the year, for the 
 nutrition of the leaf-buds. The ascent of this elaborated 
 fluid takes place from the roots into the vessels of the 
 stem, thence into those of the branches, and lastly into 
 the vessels of the developing leaf-buds. The cause of 
 this ascent is endosmose a process which has been 
 already explained. 
 
 253. Peculiar or Local Movements. The ascending 
 sap and the descending sap cannot be supposed to be 
 strictly confined within certain limits, as the organs 
 through which they pass are contiguous, and, in what- 
 ever way it may be accomplished, a transfusion or lateral 
 movement takes place. In the cells of certain plants, 
 especially those of the genus Chara, a Cydosis or cir-
 
 172 VEGETABLE SECRETIONS. 
 
 cular movement of the fluid, rendered observable by the 
 existence of opaque granules in it, is observed, the gra- 
 nules ascending by one side of a cell and descending by 
 the other. Another kind of circulation was discovered 
 by M. Schultes, who describes the proper juices of many 
 plants as undergoing a complex kind of motion, in par- 
 ticular vessels, which occur in the root and stem, and 
 appear to anastomose in their whole extent. 
 
 254. Vegetable Secretions. The descending sap is 
 not merely subservient to nutrition, but furnishes various 
 matters which are secreted or separated from its mass, 
 and afterwards elaborated by particular organs. Many 
 of these matters are ejected, and constitute what are 
 called Excretions. Whether they are to be considered 
 as components of the sap, or secretions from it, there 
 are four substances, closely allied in chemical composi- 
 tion, which are of very general occurrence : gum, sugar, 
 fecula, and lignin. 
 
 1. Gum is a substance destitute of taste or smell, in- 
 soluble in alcohol, but forming with water a viscid fluid 
 to which the name of mucilage is given. It is observed 
 in various parts of plants, as in seeds, bark, and roots. 
 The purest kinds are gum-arabic and gum-tragacauth. 
 
 2. Sugar is a substance having a sweet taste, and 
 soluble in water, as well as more sparingly in alcohol. 
 It is met with in most parts of plants. Several kinds 
 are distinguished. That in common use as an article of 
 food is obtained from a species of grass, the Sugar Cane, 
 by expression and evaporation. The sugar of the beet- 
 root, chestnut, and maple, is similar. When pure, this 
 sugar crystallizes in a regular manner, and then forms 
 candy-sugar. Grape sugar, which is extracted from the 
 grape, gooseberry, apricot, and fig, has a different taste, 
 and contains more water. 
 
 3. Fecula or Stardi is a substance composed of organic
 
 VEGETABLE PRODUCTS. 173 
 
 granules, which is extracted, by trituration in water, from 
 the roots, tubercles, and stems of various plants, and 
 chiefly from the seeds of wheat, barley, oats, and other 
 cereal grasses. Each granule is formed of a membranous 
 covering, and an inclosed substance of a gummy appear- 
 ance. The fecula is deposited at the bottom of the water 
 in the form of a white shining powder, destitute of taste 
 or smell. It forms a mucilage with boiling water, and, 
 if the solution is evaporated, a kind of jelly is obtained. 
 
 4. Lignine, which is also composed of granules, 
 having an external pellicle, is contained in the elongated 
 cells or vessels of the woody tissue of plants, and does 
 not appear to answer any other purpose in the vegetable 
 economy, but remains unchanged in the cells. It differs 
 from gum, starch, and sugar, chiefly in containing a 
 larger proportion of carbon. 
 
 255. Other Vegetable Products. Besides these four 
 substances, which appear to be the simplest modifica- 
 tions assumed by the nutritious materials found in plants, 
 there are many others, of which the more remarkable 
 are here mentioned. The Fixed Oils are combustible 
 substances, insoluble in water, and forming soaps with 
 alkalies. They occur in the fruits, and chiefly in the 
 seeds of various plants, and are divided into such as 
 thicken and become opaque when exposed to the air, as 
 olive oil and oil of almonds, and such as dry without los- 
 ing their transparency, like varnish, as linseed oil. Vege- 
 table Wax differs from fixed oil only in being solid at 
 common temperatures. It is seen on plums, oranges, and 
 the leaves of the cabbage, in the form of a very fine glau- 
 cous powder ; on the fruit of Myrica cerifera, and the 
 trunks of some palms, in a thick layer ; and it preserves 
 plants from the injurious action of moisture. Volatile 
 Oils are much more common, and are met with in the 
 bark, leaves, flowers, and pericarps of plants. They re-
 
 174 VEGETABLE PRODUCTS. 
 
 semble the fixed oils, but are distinguished from them 
 by a strong smell, a slight solubility iu water, and the 
 property of being volatilized without decomposition. They 
 are used in painting or as perfumes. Most scented sub- 
 stances or aromas owe their properties to these volati- 
 lized oils. They are found in the bark of the cinnamon, 
 the leaves of the Labiatse, such as Mint and Thyme, 
 and the rind of oranges and citrons. Camphor, which 
 is nearly allied to the Volatile Oils, is a solid, colourless, 
 transparent, highly odorous, and inflammable substance, 
 obtained by distillation from the wood of certain species 
 of Laurel. 
 
 256. Vegetable Products, continued. The Resins are 
 dry, brittle substances, insoluble in water, soluble in 
 alcohol, softened by a low degree of heat, and highly in- 
 flammable. Resins, mixed with volatile oils and benzoic 
 acid, form the Balsams, which are inflammable and odo- 
 rous. Of the former may be mentioned the resin of the 
 pines, mastic, dragon's-blood, and copal ; of the latter 
 benzoin, storax, and balsams of Peru and Tolu. Caout- 
 chouc or Elastic Gum, which flows in the form of a milky 
 juice from several trees of the equatorial zone, is neither 
 a gum nor a resin, but a peculiar substance which is in- 
 soluble in water and alcohol, coagulates in the air, becomes 
 brown, assumes the appearance of leather, and acquires 
 an extreme elasticity. Plants contain acid principles, 
 and others possess alkaline properties. The most re- 
 markable vegetable acids are Acetic Acid, or pure vine- 
 gar, furnished by the fermentation of various liquors, and 
 the distillation of wood ; Malic and Citric Acids, which 
 are extracted from fruits, and particularly from the apple 
 and lemon ; Oxalic Acid, which is found in the leaves of 
 oxalis, in combination with potash ; Tartaric Acid, which 
 occurs in the free state in the pulp of certain fruits, and 
 in combination with potash in the juice of the grape,
 
 ADVENTITIOUS SUBSTANCES IN PLANTS. 175 
 
 when it forms cream of tartar ; Prussia Add, a very active 
 poison, which is extracted from hitter almonds, and from 
 the kernel of the peach, apricot, plum, cherry, and other 
 drupes ; Gallic Acid, which produces a black colour, with 
 red oxide of iron, and is found in gall-nuts, and in most 
 harks of trees, communicating its astringent property to 
 most of the vegetable substances which contain it, among 
 others to the tannin used for preparing leather. Of the 
 alkaline substances may be mentioned Morphine, which 
 is contained in opium, or the juice extracted from the 
 white poppy, and of which the salts formed by its combi- 
 nation with acids, especially acetic acid, are very danger- 
 ous poisons ; and Quinine, which is extracted from Cin- 
 chona. Plants, moreover, contain various colouring mat- 
 ters, which are found sometimes in the roots, as madder ; 
 sometimes in the stems, as the colouring substance of 
 Brazil wood ; sometimes in the leaves, as indigo ; or in 
 the flowers, as the red of Carthatnus. 
 
 257. Adventitious Substances in Plants. Besides the 
 numerous products of Secretion, resulting directly from 
 the action of the elementary organs, there are sub- 
 stances which have been absorbed by the roots, or have 
 resulted from the combination of these substances with 
 the vegetable products. Lime is generally found in the 
 ashes of plants, in the form of a carbonate, or in union 
 with various acids. Silica also occurs in considerable 
 abundance, especially in the stems of some monocotyle- 
 donous plants. The glossy pellicle on the surface of reeds, 
 canes, and other grasses, contains a large proportion of it, 
 insomuch that if two canes be rubbed against each other 
 in the dark, they emit a light like that given out by the 
 friction of two pieces of quartz. On the inner surface of 
 the fistular joints of the Bamboo, a substance named Ta- 
 basheer is deposited, in plates or masses, at first moist 
 like paste, but ultimately resembling semi-transparent
 
 176 EXCRETIONS. 
 
 disintegrated opal. When a stack of corn has been burnt, 
 the ashes are found fused into a partially vitrified mass, 
 resulting from the silica and alkali contained in the straw. 
 Salts of potash and soda are abundant in many plants, 
 those of the latter in such as grow near the sea. Common 
 Soda or Carbonate of Soda is obtained by burning several 
 maritime plants, as Salsola Kali and Salsola Soda, as 
 well as marine algse, such as Fucus vesiculosus and 
 FWMS serratus. These substances are so abundant in 
 plants that they can hardly be considered as merely 
 adventitious ; but various other products, such as metallic 
 oxides and salts, that occur in small quantities in the 
 ashes of plants, have probably been derived from absorp- 
 tion by the roots or leaves. 
 
 258. Excretions. Many of ^the substances above 
 enumerated are to be regarded as excrementitious, espe- 
 cially wax, which is found on the surface of fruits, gums, 
 and resins, which exude from the bark ; also volatile oils 
 and glutinous juices. Stinging plants, as Nettles, secrete 
 an alkaline caustic juice, contained in a cellular bag, sur- 
 mounted by a hollow bristle. When the bristle is pressed, 
 the fluid passes through the tube, and is ejected into the 
 wound, by a mechanism precisely similar to that of the 
 poison fangs of serpents. Clammy substances are often 
 secreted on the stems by glandules or glandule-tipped 
 hairs. Among the most remarkable secretions are those 
 discharged from the roots of plants, it being found that 
 some give out acid, others milky, mucilaginous, or saccha- 
 rine substances. It has been suggested by M. De Can- 
 dolle that the theory of the succession of crops is to be 
 sought for in this circumstance. It had been observed 
 that some plants will not prosper in situations where 
 others of the same kind had previously grown, and that 
 certain plants succeed best when sown in ground pre- 
 viously occupied by certain other species. Now, among
 
 TASTE AND ODOUR OP PLANTS. 177 
 
 the substances which act as poisons to plants, it has been 
 found that most vegetable secretions are to be enume- 
 rated, and it is a general law that no plant is capable of 
 digesting its own excretions. But, although the excre- 
 tions of a plant may be noxious, not merely to its own 
 species, but to others of the same genus or family, they 
 may be harmless or even beneficial to plants of other 
 families. It seems thus probable that, by a proper 
 rotation of crops, the soil may be preserved in a state of 
 fertility, without the application of much manure. 
 
 259. Taste and Odour of Plants. The tastes of 
 plants must depend upon the nature of their juices and 
 the substances secreted from them. This subject, how- 
 ever, has received little attention, and the classification 
 and nomenclature of tastes, as well as of smells, is merely 
 empirical. Some pai'ts or substances are tasteless, or 
 nearly so, as membrane, mucilage, and resin ; sweet tastes 
 depend upon the presence of sugars ; sour, upon that of 
 acids ; bitter, upon alkaline salts or extractive matter ; 
 astringent, on acids in excess ; acrid, on volatile oils. 
 The odours of plants depend chiefly upon the emission of 
 an essential oil, which differs in the different species, 
 being more or less volatile, and in various degrees 
 miscible with water. The oil is stored in the stems and 
 leaves, and when these parts are rubbed or bruised, the 
 odour becomes more sensible. Heat generally renders 
 the odours of plants more powerful, but sometimes dis- 
 perses the odorous particles so rapidly that little smell 
 is perceptible. Some flowers emit their odour only in 
 the evening or at night, as is the case especially with 
 those Cruciferse, as the Wall-flower, that have a dingy 
 brown colour. The nomenclature of scents is not more 
 intelligible than that of tastes ; they are sweet, aromatic, 
 musky, fetid, alliaceous, acrid, nauseous, and oppressive. 
 Very different impressions are made on different indi-
 
 178 ASSIMILATION. 
 
 viduals by the scent of the same flower. Some odours 
 make very deleterious impressions on persons of weak 
 nerves, insomuch that death has sometimes resulted from 
 them. 
 
 260. Assimilation. The sap having heen elaborated 
 and conveyed to the different parts of the plant, is 
 applied to the nourishment and development of its various 
 organs. But of the manner in which this assimilation 
 of the nutritious fluid takes place, it appears that no- 
 thing is known with precision. How the first cellules 
 of the elementary tissue are produced, and in what man- 
 ner they are increased or extended, have never been 
 satisfactorily determined ; for the various organs already 
 exist in some degree of development before we can sub- 
 mit them to examination, and their extension cannot be 
 traced in continuance with the necessary minuteness and 
 attention. The process already described and that of 
 assimilation go on simultaneously, and although we are 
 sensible of the general results, we are unable to trace the 
 progress of the parts in detail. Some suppose the tissue 
 to be extended by the development of young cells within 
 the old ones, which they rupture and replace ; others 
 think that the new cells originate from the minute 
 granules or dots seen on the surface of some cells ; and 
 others are of opinion that the cells become divided by 
 transverse partitions, the space between each pair of 
 which becomes a new cell. The vascular tissue is sup- 
 posed by some to be similar in origin to the cellular tis- 
 sue, the vessels being merely elongated cells, or series 
 of united cells. Others consider the new vessels as ana- 
 logous to roots, and maintain that they proceed from the 
 buds placed in the axilla3 of the leaves. Some parts of 
 plants once formed appear to be incapable of receiving 
 further development. Of this kind is the pith, which is 
 enclosed in a cylinder of tissue that prevents its exten-
 
 PRUNING. 179 
 
 sion. The woody layers also remain stationary, the only 
 change effected upon them heing the filling up of their 
 cavities hy the deposition of lignine and other substances. 
 It appears to be by the cellular or parenchymatous tissue 
 that the development of plants chiefly takes place. The 
 pith, then, filled with fluid, is the first part that appears 
 when the stem shoots up. Scales, young stamens, and 
 pistils, and the tips of the radicles, are composed of it ; 
 in all cases of wounds, as in pruning, propagating by 
 slips, or grafting, it is the part first generated. 
 
 261. Pruning. When a limb or branch is cut off, 
 for the purpose of improving the timber of the stem, or 
 for giving the plant a more agreeable form, a portion of 
 the inner parts of the woody layers is exposed. These 
 being incapable of generating new tissue, would remain 
 exposed, and decay, were it not for the newer tissue 
 round the edge of the wound, which gradually extends 
 over its surface, so as to meet in the centre, forming 
 a complete cicatrix. In dicotyledonous trees and shrubs, 
 as has already been stated, the growth takes place at the 
 part where the outer layer of wood and the inner layer 
 of bark are in contact. Now, in the case adduced, the 
 wood covered over by the extension of the parenchyma- 
 tous tissue of the bark produces no new layer, and the 
 layer of wood formed over it does not adhere to it. As 
 the growth of the tissue that covers the wood depends 
 upon the returning sap for its nourishment, the branch 
 must not be lopped at a distance form the trunk, other- 
 wise it will not heal over, there being nojeaves upon it 
 to furnish a supply of elaborated sap, and whatever 
 descends from the stems is expended in developing the 
 tissue and lower parts of the stump of the amputated 
 limb. Since the surface of the cut never adheres to the 
 new tissue formed over it, and the wood is always more 
 or less blemished by pruning, it is obvious that the opera-
 
 180 GRAFTING. 
 
 tion should be performed when the branches are young, 
 or even when only in bud ; but if this cannot be done, 
 the cut should be made quite close to the trunk, and its 
 surface protected by some compost to prevent any degree 
 of decomposition, till it is healed over. 
 
 262. Grafting. The operation of grafting also shows 
 the superior vitality of the parenchymatous tissue, and 
 proves that the nutritious fluid circulates in the more 
 external parts. The object of this process is chiefly to 
 propagate particular varieties of fruits, which cannot be 
 obtained from seed. A bud or twig of the tree to be 
 propagated is united to another tree on which it grows, 
 the fruit produced continuing to be similar to that of the 
 original tree, and not of the stock on which it has been 
 grafted. This kind of union takes place between indi- 
 viduals of the same species, between species of the same 
 genus, or between species of different genera of the same 
 natural family, and the more nearly the two species are 
 allied, the more readily do they unite. The operation is 
 performed in various ways. When the branches of two 
 or more trees are united, the process is called Grafting 
 by approach. Usually in this case two plants are placed 
 near each other, and their branches grafted. When they 
 have become perfectly united, one of them is separated 
 from its stem, and left to grow on that of the other. 
 Another way is to cut a shoot from a tree, and attach it 
 to the extremity of the branch of another tree prepared 
 for the 'purpose by being cleft or otherwise cut. This 
 method is called Grafting by slips. A common practice 
 also, called Budding, is to remove a bud along with a 
 portion of the surrounding bark, cut out a corresponding 
 piece from another tree, and insert the bud in its place. 
 In all cases the alburnum and liber of the two trees must 
 be placed in correspondence. The graft is secured from 
 displacement or access to air for some time, and complete
 
 DO PETIT-THOUAIIS'S THEORY. 181 
 
 union takes place. In this manner are multiplied dif- 
 ferent kinds of fruits, as apples, pears, and plums, each 
 of which is only a variety accidentally raised from seed, 
 but is not capable of being further propagated in the 
 same way. It is thus apparent that in dicotyledonous 
 trees the principal seat of the vital operations is in the 
 liber, alburnum, and intervening cambium. Two of the 
 theories which explain the growth of these trees may 
 here be mentioned. One of them, of which the author 
 is M. Du Petit-Thouars, attributes the successive forma- 
 tion of the woody layers to the development of the buds ; 
 the other, or M. Mirbel's theory, to the cambium. 
 
 263. Du Petit-Thouars' s Theory. The considerations 
 upon which this theory are founded are the following: 
 Buds are the first perceptible phenomena of vegeta- 
 tion : there is one in the axilla of each leaf ; but it is 
 only in Dicotyledonous Plants, and in the Gramineae, 
 that the buds are apparent, they being in other plants 
 latent, and consisting merely of a vital point, which, in 
 certain circumstances, is capable of being developed. 
 Buds, by their development, give rise to shoots, which 
 are furnished with leaves, and generally with flowers. 
 Each bud is, in some measure, independent of the rest, 
 and may be considered as analogous to the embryo of a 
 seed. Buds may thus be called Fixed Embryos, in oppo- 
 sition to seeds, which are Free Embryos. If we examine 
 the interior of the buds on a shoot or young branch, we 
 find that it communicates directly with the pith, which 
 is at first green, and filled with sap, from which the buds 
 derive the first materials of their development. Having 
 thus supplied the buds, the internal parenchyma dries up, 
 and becomes converted into pith, properly so called. As 
 soon as the buds appear, they obey two general motions, 
 an ascending and a descending, being in this respect 
 similar to the seeds. The layer of cambium, situated
 
 182 MIRBEL'S THEORY. 
 
 between the wood and the bark, is analogous to the 
 soil in which the seed grows. The bud sends upwards a 
 shoot or young branch, and downwards into the cambium 
 fibres, or radicles, which, gliding between the liber and 
 alburnum, descend to the lower part of the plant. In 
 their course downwards these fibres meet those which 
 descend from other buds, unite with them, anastomose, 
 and thus form a layer, which acquires consistence and 
 solidity, and forms each succeeding year a new woody 
 layer. The liber, once formed, does not change its 
 nature, and undergoes no transformation. This theory, 
 which is very ingenious, and remarkably simple, has not 
 been generally adopted. 
 
 264. Mirbd's Theory. If we examine a young branch 
 at the period of vegetation, we find between the liber 
 and alburnum a layer of fluid, at first limpid, hut gra- 
 dually thickening and acquiring consistence. This fluid, 
 the Cambium, is the descending sap, mixed with part of 
 the proper or secreted juices. As it thickens, filaments 
 are seen to form in it, and it gradually assumes the 
 appearance of vegetable tissue, the development of the 
 layer continuing during the whole period of the develop- 
 ment of the buds. In this manner a new layer of woody 
 tissue is formed each year in the trunk of dicotyledonous 
 trees, being produced by a part of the cambium, which 
 is organized, and becomes solid. The alburnum formed 
 the preceding year acquires more density, and changes 
 into wood, properly so called. A thinner layer, also 
 formed from the cambium, is added to the liber or inner 
 bark. This theory is the one most generally adopted by 
 writers on vegetable physiology. 
 
 265. Continuance of Growth. Although an apparent 
 cessation of the development of plants takes place in 
 winter, after the leaves have fallen, yet even during that 
 season some slight enlargement of the buds is observed,
 
 SUMMARY OF NUTRITION. 183 
 
 and the sap is not entirely quiescent. When spring 
 advances, the increased temperature gives a continued 
 impulse to the vital powers ; the sap flows with rapidity 
 towards the twigs, and the buds are quickly developed. 
 As the summer advances, the motion of the fluids gra- 
 dually diminishes. In autumn, the huds which have 
 been formed in the axils of the leaves continue to grow, 
 while the other herbaceous parts decay ; and thus there 
 is caused a renewed, but less vigorous motion in the 
 sap, which ceases as the cold increases. As the fluids 
 are in a state of torpidity, and the development of the 
 parts arrested, in winter, trees or other vegetables may, 
 at that season, be transplanted with less injury than at 
 any other. 
 
 266. Summary of Nutrition of Organized Beings. The 
 difference between nutrition and reproduction consists in 
 this the phenomena of the former relate to the de- 
 velopment and support of the individual, those of the 
 latter to the perpetuation of the species. In each king- 
 dom of organized being, the vegetable and the animal, 
 nutrition comprises seven stages, or classes of phenomena, 
 which may be briefly represented as follows : 
 
 (1.) In both kingdoms the aliment, liquid or solid, 
 is introduced into the system by one or more fixed orifices. 
 In most animals the orifice is single, the mouth ; ex- 
 ceptions occur in rhizostomes, in which there are several 
 mouths in the form of suckers. In plants, the orifices 
 are usually numerous, being composed of the spougelets, 
 or terminations of the fibres of the root. In animals, 
 the food is liquid and solid ; in plants, it is only liquid. 
 
 (2.) The aliment, when introduced, is conveyed into 
 organs specially provided for the purpose of elaboration. 
 In plants, it is conveyed directly by the root and stem 
 to the foliaceous parts, where it is brought into contact 
 with the atmosphere. In animals there are some special
 
 184 SUMMARY OF NUTRITION. 
 
 cavities, as stomach and intestines, in which the aliment 
 undergoes a preliminary modification the unnutritive 
 portion is rejected as excrement, the remainder is con- 
 veyed onward in the form of chyle. 
 
 (3.) The liquid aliment the chyle in animals, the sap 
 in plants is conveyed to the surface, where it is brought 
 into relation with the external air. A portion of it 
 passes off by evaporation, in both kingdoms, by transpir- 
 ation from the entire surface ; or, in another sense, by 
 abundant transpiration in the lungs of animals, and by 
 exhalation by the leaves in vascular plants. 
 
 (4.) The alimentary matter, having acquired greater 
 consistency, is modified chemically by contact with the 
 atmospheric air. In animals there is an increase of 
 oxygen ; in plants, of carbon. This difference corresponds 
 with the energy, activity, and mobility of the former, 
 compared with the fixity and stationary condition of the 
 latter. In the higher animals and plants this chemical 
 effect takes place in the lungs, branches, and leaves ; 
 in the lower, in air-cavities, where the air is exposed to 
 the fluids, or by the whole external surface. 
 
 (5.) The alimentary fluid, modified by the preceding 
 operations, has become highly nutritive. In animals it 
 is now blood; in plants it is cambium. It is now deposited 
 in the tissue by the function of circulation. 
 
 (6.) A portion of the elementary molecules, contained 
 in the sap, is so deposited as to be capable of being con- 
 veyed, in the sap or lymph, from one organ to another. 
 This is the case with the fat in animals ; with tubers, 
 fleshy cotyledons, receptacles, and other fleshy deposits 
 in plants. 
 
 (7.) Some peculiar organs, called glands, are capable 
 of separating from the alimentary liquid substances of 
 very variable properties. These are secretions. Of these, 
 some are expelled, and termed excretions, as the urine ;
 
 RECAPITULATION. 
 
 185 
 
 others continue in the system for useful purposes, as the 
 bile, the saliva, <fcc. This distinction is more obscure 
 in plants. 
 
 Hence, we conclude that 
 
 AN ANIMAL 
 
 is an Apparatus of Combustion ; 
 Possesses the faculty of Locomo- 
 tion; 
 Burns Carbon, 
 
 Hydrogen, 
 Ammonium ; 
 Exhales Carbonic Acid, 
 Water, 
 
 Oxide of Ammonium, 
 Azote ; 
 Consumes Oxygen, 
 
 Neutral azotized mat- 
 ters, 
 
 Fatty matters, 
 Amylaceous matters, 
 Sugars, gums; 
 Produces Heat, 
 
 Electricity ; 
 Restores its elements to the air 
 
 or to the earth ; 
 
 Transforms organized matters into 
 mineral matters. 
 
 A VEGETABLE 
 
 is an Apparatus of Reduction 
 Is fixed and stationary ; 
 Reduces Carbou, 
 
 Hydrogen, 
 Ammonium; 
 Fixes Carbonic Acid, 
 Water, 
 
 Oxide of Ammonium, 
 Azote ; 
 Produces Oxygen, 
 
 Neutral azotized mat- 
 ters, 
 
 Fatty matters, 
 Amylaceous matters, 
 Sugars, gums; 
 Absorbs Heat, 
 Abstracts Electricity ; 
 Derives its elements from the air 
 
 or earth ; 
 
 Transforms mineral matters into 
 organic matters. 
 
 RECAPITULATION. 
 
 250. What names are given to the elaborated juice ? Are 
 its general characters easily denned ? Does it vary in its 
 qualities ? 251. What course does the sap now take ? How 
 may its descent be proved ? Where does it chiefly circulate ? 
 252. By what organs does this sap descend? What argu- 
 ments in proof of this have been employed ? At what period 
 does the elaborated sap ascend in a plant ? Eor what purpose 
 does it ascend ? Is there any analogy between this process 
 and that of germination ? What is the Cambium ? What 
 change stake place in it? 253. Does the descending sap 
 follow a strictly defined course ? What motions are observed
 
 186 RECAPITULATION. 
 
 in the cells of Chara ? What kind of circulation has been 
 seen in the proper juices? 254. What are the substances 
 most generally found in the sap ? Give an account of Gum. 
 What are the characters of Sugar ? Describe Fecula. To 
 what use is Lignin peculiarly applied ? 255. Mention some 
 other vegetable products. What are the general characters 
 of the Fixed and Volatile Oils ? Mention some plants that 
 produce wax. How is Camphor obtained ? 256. What is 
 the nature of Resin ? Describe Caoutchouc. What are 
 some of the most remarkable vegetable Acids? Mention 
 some Alkaline substances. In what parts are colouring mat- 
 ters contained ? 257. What adventitious substances are con- 
 tained in plants ? What is Tabasheer ? Do many plants 
 contain potash? In what kinds is soda found? 258. What 
 substances may be considered as excrementitious ? How do 
 the excretions of the roots of plants account for the rotation 
 of crops? 259. Upon what do the tastes of plants depend? 
 What is the principal cause of their odours ? 260. How are 
 the elaborated juices applied to the development of the organs? 
 Mention the three different opinions regarding the develop- 
 ment of the cellules. How is the vascular tissue supposed 
 to be formed ? What parts remain stationary after being 
 formed ? On what tissue does the growth of plants chiefly 
 depend ? 261. What is meant by Pruning ? What takes 
 place when a branch is cut from a tree ? Should branches 
 be cut off short, or at some distance from the trunk ? 262. 
 What is Grafting? Describe its three principal kinds. 
 What parts must be placed in correspondence ? What results ? 
 263. What is the theory of Du Petit-Thouars with regard to 
 the growth of Dicotyledonous trees ? 264. State the theory 
 of M. Mirbel on the same subject. 265. Is the progress 
 of vegetation entirely arrested during winter ? At what 
 season may vegetables be transplanted with least injury? 
 266. What is the precise difference between Nutrition and 
 Reproduction? Trace the analogies presented by the two 
 organized kingdoms in reference to the seven successive 
 stages of nutrition.
 
 FUNCTION OF REPRODUCTION. 187 
 
 CHAPTER XXIII. 
 FUNCTION OF REPRODUCTION. 
 
 PROPAGATION BY DIVISION. REPRODUCTION, PROPERLY SO 
 CALLED. FLORATION. FECUNDATION. MATURATION. 
 DISSEMINATION. 
 
 267. General Idea of Reproduction. The process by 
 which the vegetable prepares the means of continuing 
 its specific form, by generating new individuals, is named 
 Reproduction. The term Propagation is of more com- 
 prehensive meaning, for it includes not only the natural 
 means of continuing the species, but also those to which 
 recourse may be had by cultivators of plants. Naturally, 
 also, there are two modes by which vegetables are propa- 
 gated : Reproduction without fecundation, and Reproduc- 
 tion by fecundation. Plants may be multiplied by means 
 of germs, which are formed on all parts of their surface, 
 and are developed by the action of the nutritious fluids, 
 when in circumstances rendering them capable of receiv- 
 ing their influence. These latent buds or germs may 
 form either roots or aerial shoots, the former being pro- 
 duced when a part in which the juices abound is sur- 
 rounded with moist soil, or protected from air and light ; 
 the latter, when it is exposed to the influence of these 
 agents. Germs of this kind, as well as Buds, properly so 
 called, and Bulbils, are parts of a plant which may be 
 separated, and yet continne to live, and have an inde- 
 pendent existence. They give rise to a continuation of 
 the individual, not merely in regard to its general resem- 
 blance to the species, but even in all the peculiarities by 
 which it is distinguished from other individuals. Another
 
 188 PROPAGATION BY SUBDIVISION. 
 
 mode of propagation is by seeds, which are impregnated 
 ovules, subsequently developed. The two modes may be 
 distinguished as Propagation by Subdivision, and Repro- 
 ducf,ion, properly so called. 
 
 268. Propagation by Subdivision. When the descend- 
 ing sap is increased in quantity, or its motion diminished 
 in any part, there are evolved buds, some of which pro- 
 duce branches, others flowers. Thus, in the axils of all 
 the leaves the sap is somewhat retarded in its progress, 
 and there is naturally developed there a bud, which 
 changes into a branch. This branch may be considered 
 as a distinct individual, which has been produced upon 
 another individual, from which it derives its nourishment, 
 but which may be separated from it, and obtain nourish- 
 ment either from the soil in which it is placed, or from 
 another individual to which it may be affixed by grafting. 
 This process of grafting, which has already been spoken 
 of, \ 262, and which consists in transferring a bud or 
 branch from one individual to another, is of great use to 
 cultivators, as it serves to perpetuate varieties, which 
 could not be reproduced by seeds; economizes time by 
 quickly procuring a great number of trees, which are 
 with difficulty multiplied by other means; and accelerates 
 the fructification of certain plants by several years. 
 Many plants may be propagated by slips or cuttings, a 
 portion of a twig being separated from the parent plant, 
 and placed in the ground, where it takes root. Indi- 
 viduals are also multiplied by bending a branch and 
 covering it with earth, into which it sends roots ; or by 
 surrounding with earth the extremity of a branch, after 
 applying a ligature to it, to make it push out roots, 
 after which the branch is cut off. The tubers which 
 form on the roots of certain plants, on being removed 
 and again planted, produce new individuals, as in the 
 Potato. When a plant, as the Strawberry, sends out
 
 REPRODUCTION AND FLORATION. 189 
 
 shoots or runners, 54, the buds at their extremity take 
 root and develope leaves, after which the runners decay, 
 or are cut across, and thus new individuals may he ob- 
 tained. Many plants, as elms and poplars, throw up 
 suckers from their roots, at some distance from the 
 trunk, which, under favourable circumstances, may be- 
 come distinct trees. But although many plants may be 
 propagated by these methods, all those which produce 
 flowers secure the continuation of their species by a dif- 
 ferent process. 
 
 269. Reproduction. By Reproduction, properly so 
 called, is meant the formation of seeds, containing the 
 germs of new individuals. To this function are sub- 
 servient the Perianth, Stamens, and Pistils. A seed 
 is a germ or embryo, which having been formed upon 
 the parent plant, and for some time derived its nourish- 
 ment from it, has become free, after being fecundated, 
 or in other words, after receiving the principle of life, or 
 the power of becoming developed under particular cir- 
 cumstances. The seed, which separates from the parent 
 plant, is furnished with proper envelopes and with organs 
 of nutrition. It is not, like the bud or bulbil, a continua- 
 tion of the same individual ; but a new individual re- 
 sembling that from which it has been derived only in the 
 parts essential to the species. Reproduction by means 
 of seeds comprehends several distinct periods or processes, 
 as, 
 
 (1.) Floralion, or the development of the flower. 
 (2.) Fecundation, or the function of the pollen. 
 (3.) Maturation, or the development of the fruit. 
 (4.) Dissemination, or the dispersion of the seeds. 
 
 270. Floration. Flowers are formed in some plants 
 long before they appear externally : in Hyacinths, the 
 racemes exist in the bulb before the leaves are developed ; 
 and in Palms, the rudimentary regimes (see p. 75), exist
 
 190 STIMULANTS TO FLOWERING. 
 
 one, two, or even, it is said, seven years before they are 
 developed exteriorly. The causes of the production of 
 Flowers are unknown. Some plants flower in a few 
 weeks after germination, others take some months, and 
 others require several years. Flowers are not, as was 
 long supposed, mere ornaments to plants, for they con- 
 tain the organs essential to reproduction, namely, the 
 stamens and pistils. When first distinguishable, their 
 parts are in a rudimentary state, especially the perianth, 
 which for some time continues to enlarge much less 
 rapidly than the stamens. All the organs, however, 
 gradually enlarge until expansion takes place. In the 
 bud, the calyx usually covers and protects the other 
 parts, the corolla is generally closed over the stamens 
 and pistils, the anthers are developed, and burst at the 
 period of expansion, or presently after. 
 
 271. Stimulants to Flowering. The period of flower- 
 ing is accelerated by an increase of temperature, and 
 retarded by cold. These causes also operate in de- 
 termining the buds to assume the character of leaf-buds 
 or flower-buds. Superabundant moisture retards the 
 flowering, and renders the flower-buds less numerous, as 
 in the case of a too profuse supply of nutriment, or of an 
 unusual excitement by heat ; hence the fruit-trees of 
 temperate climates, on being carried to the tropics, often 
 vegetate vigorously, although they become barren. It 
 seems to be a general law that the number of flowers 
 produced by a plant is in some measure proportional to 
 the quantity of nutritious matter which it has accumula- 
 ted. Thus, after a warm and bright summer, during 
 which the branches have acquired only a moderate de- 
 velopment, and nutritious matter has been stored up, a 
 profusion of flowers is produced. There appears to be 
 an antagonism between the reproductive and the nutri- 
 tive functions. In flowering plants, it is well known
 
 PERIODICITY OF FLOWERING. 191 
 
 that an excessive supply of nutriment will cause an evo- 
 lution of leaves at the expense of the flowers, so that 
 what would have been floiver-buds are converted into 
 leaf-bids; or the parts of the flower essentially con- 
 cerned in reproduction, as the stamens and pistil, are 
 converted into foliaceous expansions, as in the produc- 
 tion of double flowers, as they are called, from single 
 flowers, by cultivation. In the Algaj, which are plenti- 
 fully supplied with water, the dimensions attained by 
 the nutritive parts of plants are exceedingly dispropor- 
 tionate to the reproductive apparatus ; while in the 
 Fungi, the whole plant seems made up of reproductive 
 organs, and as soon as these have brought their germs 
 to maturity, it ceases to exist. 
 
 272. Periodicity of Flowering. Different species 
 flower at different periods of the year, varying to a con- 
 siderable extent, however, according to the state of the 
 weather, and the degree of temperature. Thus, the 
 Christmas Rose flowers in January, the Snowdrop in 
 February, the Crocus in March, the Primrose in April, 
 the Lily of the Valley in May, the Wood- Vetch in June, 
 the Yellow Iris in July, the Tansy in August. The rea- 
 sons of this variation we are unacquainted with; and, 
 when we attribute it to the peculiar character of the 
 species, we merely use words to conceal our ignorance. 
 Owing to some peculiarity in the constitution of indivi- 
 duals, they flower earlier or later than others of the 
 same species ; and in both cases, advantage is taken of 
 the circumstance by propagating peculiar races, which 
 afford the cultivator a longer succession of crops. After 
 producing a very ^abundant crop, which has exhausted 
 the nutritious matter prepared in the stem, few flowers 
 are produced the next season ; and thus, apple and pear 
 trees usually have alternate years of productiveness and 
 comparative sterility. Many plants, as the Elm and
 
 192 HORARY EXPANSION OF FLOWERS. 
 
 Alder, flower before producing leaves ; but the greater 
 number, after. Sometimes, when the leaves have been 
 destroyed in summer by drought or insects, a second 
 crop of flowers is produced in autumn. The period of 
 flowering in plants is analogous to that of puberty in 
 animals. Herbaceous plants flower in the first or second 
 year, rarely later; woody plants, generally later; and 
 this protracted period corresponds with their tardier 
 growth and longer existence. The flowering period is 
 earlier in warm than in cold climates ; beyond a certain 
 geographical limit, it occurs not at all. 
 
 273. Horary Expansion of Flowers. The flowers of 
 particular species of plants open at certain periods of the 
 day, some in the morning, others at noon, and others 
 in the evening. Most plants, however, appear to have 
 no determinate period in this respect, their flowers, when 
 once expanded, continuing open until they decay. Lin- 
 naeus named those flowers Ephemeral which open at a 
 particular time, and wither in the course of a day ; and 
 Equinoctial, such as open and close several days in suc- 
 cession at the same hour, some of them being diurnal, 
 and others nocturnal. He constructed tables, which he 
 fancifully termed Flora's Time-pieces, Horologia Florae, to 
 show the hours of expansion of various flowers. Thus : 
 
 Tragopogon pratense, opens from 3 to 5. 
 
 Papaver nudicaule, . . at 5. 
 
 Hypochseris maculata, . . 6. 
 
 Nymphsea alba, . 7. 
 
 Anagallis arveusis, . . 8. 
 
 Calendula arvensis, . . 9. 
 
 Arenaria, .... 9, 10. 
 
 Mesembryantheraum, . . 11. 
 
 274. Functions of the Perianth. The alyx and 
 corolla, when present, obviously serve to protect the 
 sexual organs. The petals usually fall off before the
 
 FECUNDATION. 193 
 
 fruit is matured, but the calyx often remains, enlarges, 
 and covers the pericarps. Sometimes the perianth forms 
 appendages of various kinds to the fruit, as in the Com- 
 positce, in which the calyx constitutes the pappus, 
 \ 137. As no part of a plant can be intended merely for 
 ornament, the corolla must answer some important pur- 
 pose with reference to the production of the seed ; but 
 the functions of the perianth are little known, and as it 
 is sometimes absent, it is imagined by some to be in a 
 manner unessential, although even in such cases its office 
 may be supplied by the glands or other parts. It has 
 been conjectured that the petals and nectaries secrete a 
 fluid intended for the nourishment of the anthers and 
 ovules ; and this process has been compared to that of 
 germination, to which it bears a further analogy by the 
 development of heat. This phenomenon is most remarkable 
 in Arum, as has already been mentioned, \ 234. 
 
 275. Fecundation. When the flower has attained a 
 certain degree of development, the pollen formed by the 
 anther falls upon the stigma, and thus causes the fecun- 
 dation of the ovules contained in the ovarium or lower 
 part of the pistil. It is easy to prove that the action of 
 the pollen upon the pistil is absolutely necessary for the 
 fecundation of the ovules and the production of the seeds 
 which are developed in that organ. 1. In dioecious 
 plants, as the Poplar and Bryony, the stamens and pistils 
 are on different individuals ; and it has been found that 
 the pistils do not fructify, or at least do not yield fertile 
 seeds, without the agency of the pollen, as is evident 
 when the staminiferous are separated from the pistil- 
 liferous plants. 2. In monoecious plants, as the Maize, 
 in which the stamen and the pistils occur in different 
 flowers, if the staminiferous flowers be removed, the pistil- 
 liferous will not produce fertile seeds. 3. In artificial, 
 fecundation, the pollen of a plant is placed upon the
 
 194 SEXES ITT PLANTS. 
 
 stigma of another plant closely connected with it, and 
 seeds are produced as in the natural course. It has heen 
 known to the people of the East, from time immemorial, 
 that the Date Palm, which is dioecious, will not perfect 
 its fruit unless some of the staminiferous individuals are 
 cultivated in the vicinity of the fruit-bearing trees, or 
 unless bunches of the male flowers should be suspended 
 near them. In Egypt, and other Eastern countries, the 
 female trees only are cultivated, and bunches of the male 
 flowers are brought annually from the deserts. It is 
 stated that when the French were in Egypt, in 1800, 
 the inhabitants were prevented from procuring the 
 blossom, and a general defect of the date crop ensued. 
 Another proof is derived from the production of hybrids; 
 for if the stamens of a flower be removed, and its pistil 
 impregnated with the pollen from another plant of a 
 different species of the same genus, the seeds will be 
 matured, and on germinating will produce plants having 
 characters intermediate between those of the two species. 
 It is thus obvious that the stamens and pistils are the 
 sexual organs of plants. 
 
 276. Sexes in Plants. The distinction and uses of 
 the stamens and pistils were even in some degree known 
 to various individuals before the time of Linnaeus, who, 
 however, was the first to demonstrate in a satisfactory 
 manner the sexes of plants, or at least, to bring the 
 subject more particularly into notice, by employing the 
 sexes as the basis of his classification. However, the 
 existence of stamens is not necessary in all plants to 
 produce the germs of new individuals ; for in Ferns, 
 Lichens, Fungi, and other flowerless plants, male and 
 female organs are not discoverable. It has been alleged, 
 too, that Hemp and Spinach sometimes produce fertile 
 seeds without the contact of pollen ; but even should this 
 occasionally be the case, it would not militate against
 
 FORMATION AND PROTECTION OP POLLEN. 195 
 
 the general law, for in these dioecious plants some male 
 flowers might exist among the female, and the pollen is 
 often wafted by the winds to almost incredible distances. 
 Thus, it is said that in 1805, a female date palm at 
 Brindes, which regularly flowered, but never bore fruit, 
 was fecundated by a male plant of the same species, 
 thirty miles off, at Otranto, which had then only attained 
 a sufficient height to overtop the trees in its neighbour- 
 hood, and thus allow its pollen to be dispersed. 
 
 277. Formation of Pollen. The cells of the anthers 
 are at first filled with a mass of cellular tissue, in each 
 vesicle of which are one or more grains of pollen. These 
 grains gradually enlarge, and at length rupture the 
 vesicles, when the remains of the cellular tissue form loose 
 shreds or fibres intermixed with the pollen. Each grain 
 is generally composed of two membranes, of which the 
 outer presents various appearances, while the inner is an 
 extremely delicate pellicle. The granules, which it con- 
 tains, are of various forms, being spheroidal or cylindrical. 
 The grains themselves appear to have no attachment to 
 the walls of the anther, and the granules in the fovilla 
 often exhibit a rotatory motion. 
 
 278. Protection of Pollen. When matured pollen is 
 placed in water, it presently dilates, bursts, and emits 
 a mass of granules. It is therefore necessary that it 
 should be protected from moisture. In many cases the 
 anthers are matured before the corolla opens, as is the 
 case especially in all the Compositse. Plants that grow 
 in water elongate their peduncles until the flowers reach 
 the surface, where they float, as in Nymphcea, or emerge 
 to a considerable height, as in Alisma. In Zostera ma,' 
 rina, the flowers, although developed under water, are 
 placed within a cavity filled with air, and are thus effi- 
 ciently protected. Perhaps the most remarkable instance 
 of this protection of the pollen from the action of water,
 
 196 DISPERSION OF POLLEN. 
 
 is that exhibited by an aquatic plant, Vattisneria spira- 
 lis, a native of the south of Europe. It is dioecious, and 
 grows at the bottom of the water. The female flowers 
 are borne on peduncles several feet long, and twisted in 
 a spiral manner, which allows them to be elongated or 
 shortened. The male flowers, on the contrary, have very 
 short peduncles. At the period of fecundation, the 
 female flowers ascend to the surface of the water to ex- 
 pand, the male flowers detach themselves from their 
 peduncles, expand at the surface, situated around or in- 
 termingled with the female flowers. Soon after fecun- 
 dation is effected, the female flowers, by the contraction 
 of their peduncles, are drawn back into the water, and 
 there perfect their seeds. 
 
 279. Dispersion of Pollen. When the pollen is ma- 
 tured, it bursts the anthers, escapes, and is scattered 
 around. The stigma, which is adapted for receiving it, 
 by being moistened with a clammy fluid, or furnished 
 with filaments, is so placed, with reference to the anthers, 
 as to insure the pollen falling upon it. Thus, some- 
 times when the pistil is much longer than the anthers, 
 the flower droops; when it is shorter or equal, the flower 
 is erect. Some flowers incline upwards, others down- 
 wards, when fecundation is about to take place, so as to 
 put the stigma in a proper position for receiving the 
 pollen. To favour the emission of the pollen, and its 
 reception by the stigma, the fecundating organs perform 
 very remarkable motions. Frequently the anthers open 
 by the side of the pistil, with a kind of explosion, and 
 thus cast the pollen upon it ; the stamens sometimes ap- 
 proach the pistil at the time of emission, or bend their 
 filaments so as to place the anthers over the stigma ; or 
 the pistils themselves incline toward the stamens. Nu- 
 merous other contrivances, contributing to the same gene- 
 ral effect, might be mentioned. The pollen is dispersed
 
 ACTION OF THE STIGMA. 197 
 
 partly by the elasticity of the anthers in bursting, partly 
 by its weight, and partly by the action of the air. In 
 dioecious plants especially, when the male plants are 
 often placed at a great distance from the female indivi- 
 duals, the dispersion is operated by the winds. Dry 
 weather is necessary for the free dispersion of the pollen, 
 and sometimes, when the rains are heavy and continued, 
 the process is rendered defective. 
 
 280. Action of the Stigma. The grains of pollen 
 which have fallen upon the stigma adhere to the glutinous 
 fluid with which it is covered. After they have remained 
 for some time there, the outer coat of each grain bursts, 
 and the granules, contained in the delicate inner mem- 
 brane, are protruded. This membrane, now termed the 
 pollen-tube, contains, as has been stated, a liquid, the_/b- 
 villa, in which are numerous pollen-granules. The pol- 
 len tubes penetrate between the vesicles of the cellular 
 tissue of the stigma, rapidly increase in length, extend 
 down the style, make their way into the cavity of the 
 ovarium, traverse the placenta, and surround the ovules. 
 Each pollen-grain may emit a different number of these 
 tubes or vermiform appendages ; there may be only one, 
 or two, or three, as in the triangular pollen of Onagra- 
 ceae ; Amici thinks that one grain may emit from ten to 
 thirty of these tubular bodies. At this period the stigma 
 has been compared to a velvet pin-cushion, with pins in- 
 serted into it, the pollen-grain representing the head of 
 the pin, the tube its stem. Amici supposes that the 
 pollen-tubes extend throughout the entire length of the 
 style to the placenta which bears the ovules. Brongniart, 
 on the contrary, says, that after penetrating more or less 
 deeply into the style, they burst, and that the granules 
 pass freely by the intercellular spaces to the ovules. 
 
 281. Theories of Fecundation. The analogy which 
 subsists between the granules of thefovitta and the sper-
 
 198 SCHLEIDEN'S VIEWS. 
 
 malic animalcules of animals, has given rise to three 
 theories of fecundation: 1, the germ is furnished by 
 the male organ, and nourished hy the female ; or, 2, it 
 is produced by the female, and developed by the stimu- 
 lant action of the male ; or, 3, it is the result of a mate- 
 rial combination of elements produced by both. The last 
 theory is that of Buffon, and accords with the fact that 
 the product partakes of the nature of both parents ; the 
 second explains the development of seeds without fecun- 
 dation, as observed by Spallanzani in dioecious plants ; 
 the first agrees best with the results of positive obser- 
 vation. 
 
 282. Schleideri's Views. Schleiden published his views 
 in 1837. He believes that the passage of the pollen- 
 tubes from the stigma to the ovulum is the general pro- 
 cess in the fructification of phanerogamous plants ; that 
 one, seldom several, of these tubes traverse the intercel- 
 lular spaces of the nucleus ; and that the tube which 
 reaches the embryo-sac presses it forward, indents it, 
 and then appears like a cylindrical bag, forming the 
 commencement of the embryo, which, therefore, is stated 
 to be nothing more than a cell of the leaf-parenchyma 
 ingrafted upon the summit of the axis. According to 
 this view, the embryo is formed by the pollen-tube and 
 the indented embryo-sac; and in plants whose ovula con- 
 tain several embryos, there will be just as many pollen- 
 tubes present as there are embryos ; whence there is 
 derived the important conclusion that the two sexes of 
 plants have been named altogether erroneously, each 
 pollen-grain being the germ of a new individual; that the 
 embryo-sac, on the contrary, should be,considered as the 
 male principle, which only determines dynamically the 
 organisation of the material substratum. 
 
 283. Meyen's Views. In opposition to Schleiden's 
 views, Meyen states 1, that, in many cases, no pollen-
 
 THE GERM-VESICLE. 199 
 
 tubes have been observed during impregnation ; and, 2, 
 that, in many cases, the embryo-sacs are wholly want- 
 ing. He observes that, in most cases in which embryo- 
 sacs occur, they are formed out of the apex of the 
 nucleus, and grow upward to meet the pollen-tube ; that 
 the union of the pollen-tube with the apex of the embryo- 
 sac is the very act of impregnation ; that, after this 
 union, there originates, in some cases, probably by the 
 reciprocal dynamical action, a small protuberance at the 
 place of union, which grows larger and larger, becomes 
 filled with a turbid, slimy substance, and, separating 
 itself from the pollen-tube, becomes a vesicle, which 
 very soon expands in length, and grows deeply into the 
 embryo-sac. This vesicle he terms the germ-vesicle, and 
 considers it the first product resulting from the sexual 
 action which the pollen-tube exerts on the apex of the 
 embryo-sac. The germ-vesicle is not the result of a 
 violent irruption of the pollen-tube into the embryo-sac, 
 whose membrane would thereby be indented ; but it is 
 formed of the substance of the two cohering membranes, 
 viz., that of the end of the pollen-tube, and that of the 
 apex of the embryo- sac. 
 
 284. The germ-vesicle is nourished by the substance 
 in the interior of the end of the pollen-tube, and by that 
 in the interior of the embryo-sac ; and from the union of 
 these two substances and their innate formative proper- 
 ties, results the new product, viz., the base for the future 
 embryo. There is no ejaculation of the fructifying con- 
 tents of the pollen-tube into the cavity of the embryo- 
 sac, but the fructifying substance passes, in very slight 
 quantity only, into the forming germ-vesicle ; soon after 
 which, this free communication of the originated germ- 
 vesicle with the pollen-tube ceases, by a constriction 
 resulting from the formation of a diagonal septum. Upon 
 this, in most cases, the end of the polleu-tube shrivels,
 
 200 MATURATION OF THE FRUIT, 
 
 and very soon its former communication with the embryo- 
 sac ceases entirely. 
 
 285. The germ-vesicle now expands in length, growing 
 up into the depth of the embryo-sac, and usually repre- 
 sents a cylindrical tube, from whose end a simple globu- 
 lar cell then separates, which is the young embryo. The 
 other remaining part of the cylindrical tube forms the 
 funiculus of the embryo, assuming in different plants 
 various forms and structure. After the formation of the 
 young embryo, the funiculus generally dies off, and dis- 
 appears, without leaving a trace behind it. 
 
 286. Conclusions. The following conclusions are 
 drawn from the observations above detailed: 1. The 
 embryo, in all cases in which it is formed in the interior 
 of the embryo-sac, does not proceed directly from the pollen- 
 tube, but is formed at the extremity of an organ, subse- 
 quently serving as it funiculus, which originates from 
 the prolongation and further development of the germ- 
 vesicle. 2. The embryo, on its first appearance, is nothing 
 more than a simple globular cell, and thus presents the 
 form and structure of the simplest plant. 
 
 287. Maturation of the Fruit. When fecundation is 
 accomplished, the nutritious fluids which were equally 
 distributed among all the parts of the flower cease to 
 supply the stamens, then the corolla, often also the styles, 
 and the calyx. The stamens and corolla thus shrivel 
 and fall off, as do the style and stigma, and in many 
 cases the calyx. The ovarium, to which the fluids are 
 now exclusively directed, becomes developed, and assumes 
 the name of Fruit. From the time when it thus begins 
 to enlarge, until the seeds are perfected, is the period of 
 Maturation, or of Fructification, properly so called. 
 
 288. Development of the Ovules. When the Ovules 
 are first seen, they are small protuberances arising from 
 the surface of a cavity in the ovarium, and present no
 
 DEVELOPMENT OF THE OVOLE8. 
 
 201 
 
 distinct traces of organization, (Fig. 14, a). Soon after 
 they elongate, b, c, d, and are found to consist of an 
 internal part, or nucleus, composed of cellular tissue, 
 and of two coats, p, s, by which the nucleus is partially 
 invested. These coats gradually extend, so as at length 
 to cover the nucleus, leaving only a small orifice, named 
 the Foramen, e, f. The outermost coat is named Pri- 
 mine, the inner Secundine. The nucleus itself is com- 
 posed of two, sometimes three sacs ; the outer, or Tercine, 
 f, t, thick and fleshy; the inner, or Quartine q, delicate. 
 
 (Kg. U.) 
 
 As the ovule enlarges, it changes its position. The 
 apex, which at first was on the side of the ovule, opposite 
 the part by which it is attached to the ovary, is brought 
 close to its base. The place at which the secundine is 
 attached to the primine, and which is named the Cha- 
 laza, z, is distinct from the place where the podosperm 
 or funiculus is attached to the primine. The vascular 
 
 (Kg. 1*0 
 
 tissue which passes through the podosperm extends 
 through the substance of the primine, from the hilum to
 
 202 PROGRESS OF THE SEED. 
 
 the chalaza, forming a fasciculus named the Raphk. 
 When the hilum and the chalaza are contiguous, and 
 the foramen is at the other extremity, the ovule is said 
 to he Orthotropous, (Fig. 15, o). This is the case with all 
 ovules in their earliest stages. When a greater develop- 
 ment of the integuments and nucleus takes place on one 
 side than on the other, the ovule hecomes hent, and is 
 said to he Campylotrop&us, c. When the chalaza is dis- 
 tant from the hilum, so that the position of the ovule is 
 reversed, it is named Anatropous, a. 
 
 289. Progress of the Seed. Soon after the pollen- 
 tuhes have passed down the stigma into the ovarium, the 
 emhryo makes its appearance, as a minute vesicle, af- 
 fixed to the top of the embryonic sac, with its radicle 
 directed towards the foramen, and the cotyledons directed 
 towards the chalaza. All the parts of the ovule gra- 
 dually increase; the primine and secundine lose their 
 juices, and form a single skin or testa ; sometimes the 
 nucleus itself becomes similarly exhausted ; and some- 
 times nutritious matter is deposited within the tercine, 
 or outer membrane of the nucleus. This nutritious 
 matter, or amnios, in many cases is not entirely absorbed 
 by the ovule, but remains, and constitutes the albumen. 
 The embryo continues to increase, while the envelopes 
 diminish, and ultimately forms the greater part of the 
 seed, which, on attaining maturity, consists of the em- 
 bryo, endosperm or albumen when present, and a single 
 covering, the episperm or testa, composed of the remains 
 of all the coats blended together. Should some of the 
 ovules not be impregnated they soon wither, and in 
 ovaries containing numerous ovules it sometimes hap- 
 pens that only one ovule is perfected, as in the Oak 
 and Horse-Chestnut, of which the pericarps originally 
 contain several. The mature seed has already been 
 described, 190.
 
 PROGRESS OF THE FRUIT. 203 
 
 290. Progress of tlie Pericarp or Fruit. While the 
 ovules gradually enlarge, the pericarp acquires a corre- 
 sponding development, becoming more and more leathery, 
 woody, cartilaginous, or membranous, and changes from 
 green to brown or white. In many cases the pericarp 
 increases iu a much greater ratio than the seeds, becomes 
 succulent, acquires various bright colours, and then con- 
 stitutes what is popularly termed a fruit. The rapid 
 development of the fruit draws the sap with increased 
 rapidity towards the branches on which it is situated, so 
 as to cause a speedy exhaustion of the nutritious mate- 
 rials deposited in the stem. Hence the thinning of the 
 fruit of a plant, by increasing the supply afforded to that 
 which is left, insures a greater development in the indi- 
 viduals. Some plants ripen their fruit in a few days 
 after flowering ; most of the grasses take from fifteen 
 days to a month; many, as the Raspberry and Straw- 
 berry, take about two months ; the Lime and Bird-cherry, 
 three; the Horse-Chestnut and Whitethorn, four; the 
 Apple and Pear, five; the Beech and Walnut, six; the 
 Olive, seven; the Colchicum, eight or nine; most Pines, 
 ten or eleven; but some of them more than a year; and 
 some Oaks require eighteen mouths. The progress of 
 development of the seed is much accelerated by increase 
 of temperature. The removal of a ring of bark from the 
 branches or stems has a similar effect, by preventing the 
 elaborated juices from descending towards the root. 
 
 291. Action of fruits upon the Atmosphere. Accord- 
 ing to M. Th. de Saussure, fruits, while green, act much 
 in the same manner as leaves, differing only in the in- 
 tensity of their action. In the night they absorb the 
 oxygen of the atmosphere, and replace it with carbonic 
 acid, which the partially re-absorb. If exposed to the 
 sun, they disengage, entirely or partially, the oxygen 
 which they inspired at night, and preserve no trace of
 
 204 CHEMICAL CHANGES IN THE FRUIT. 
 
 carbonic acid in their own atmosphere. Many fruits, on 
 being detached from the plant, thus add oxygen to air, 
 which contains no carbonic acid. When their vegetation 
 is very feeble, or extremely languid, they vitiate the air 
 under all circumstances, but less in the sun than in the 
 shade. Green fruits detached from a plant, and exposed 
 successively to the action of the sun and of darkness, 
 change the air little or not at all, either in purity or volume. 
 In their natural state they decompose, either entirely or 
 in part, not only the c arbonic acid they have produced 
 during the night, but also such quantity as may be artifi- 
 cially added to their atmosphere. 
 
 292. Chemical Changes in the Fruit. If we examine 
 the changes which the fleshy parts of fruits undergo in 
 ripening, we first remark that their fibrous or cellular 
 tissue is merely lignin, in most cases lighter and less 
 dense than common lignin, but in the stony parts of 
 fruits denser and heavier. The fluid in succulent peri- 
 carps consists of sap lying in the intercellular passages, 
 and the matter contained in the cellules. It contains, 
 besides a great quantity of water, sugar, gum, malic 
 acid, malate of lime, colouring matter, a vegeto-animal 
 substance, and an aromatic secretion peculiar to each 
 fruit, besides several other substances in particular cases. 
 On comparing ripe with unripe fruits, it is found that a 
 large proportion of water has disappeared. This diminu- 
 tion appears to depend partly upon the fruit's absorbing 
 less water as it approaches maturity, and partly upon 
 the combination of a portion of the water it has received 
 with its tissue. Sugar, on the contrary, continually in- 
 creases as the fruit advances. It is sometimes in a con- 
 crete state, as in the Grape and Fig; sometimes liquid; 
 and seems to be formed at the expense of other matters, 
 which are proportionally diminished, gum, jelly, and 
 fecula being very easily convertible into sugar. The other
 
 COMPOSITION OF RIPE SEEDS. 205 
 
 matters increase in some fruits, and diminish in others. 
 In general, it may be stated, that the solid part of suc- 
 culent fruits consists of lignin, and their fluid parts of 
 water mixed with gum, malic acid, rnalate of lime, colour- 
 ing matter, and vegeto-animal matter, together with an 
 aromatic substance peculiar to each species. 
 
 293. Composition of Ripe Seeds. In the progress of 
 development of the seed, the foramen first closes, the em- 
 bryo makes its appearance iii the form of an opaque 
 speck near the summit of the nucleus, gradually pro- 
 jects into the cavity of the ovule, and absorbs the fluid 
 with which it is surrounded, until, when ripe, no water 
 remains in an unfixed state. During its solidification, it 
 exchanges its saccharine matter for the amylaceous, 
 oleaginous, resinous, and other secretions peculiar to it. 
 There is also deposited among its tissue a quantity of 
 earthy matter and of carbon, which gives it a variable 
 degree of hardness, and it is then heavier than water. 
 Complete maturity is not necessary to enable seeds to 
 germinate, as may be seen in corn, which in wet seasons 
 often germinates on the stems ; but it seems essential to 
 their preservation for a certain length of time. 
 
 294. Dissemination. The manner in which seeds are 
 dispersed varies according to the nature of the plant, and 
 its peculiar conditions. Sometimes, they fall immediately 
 around the parent plant, and spring up, if numerous, to 
 the exclusion of other plants. Many seeds and pericarps 
 are furnished with appendages, by means of which they 
 are transported to a great distance by the winds. Of 
 this kind are the fruits of the Ash and Sycamore, which 
 have wing-like membranes ; of the Valerians, which have 
 the calyx developed into filaments; and of the Thistles, 
 Hawkweeds, and other Compositce, which are surmounted 
 by a pappus. Fleshy fruits fall directly to the ground, 
 where they rot, unless eaten or removed by animals.
 
 205 DISSEMINATION. 
 
 The seeds of many of them, however, are encased in a 
 hard envelope, which resists the action of moisture, and 
 protects them from the influence of the putrid mass by 
 which they are surrounded. Such fruits are often eaten 
 by animals, which digest the pulp only, the seed being 
 passed by them. Seeds enclosed in capsules are usually 
 dispersed by the wind, which shakes out a few at in- 
 tervals, but sometimes the valves open with a jerk, and 
 scatter the seeds to a distance. " The various modes," 
 says Sir J. E. Smith, " by which seeds are dispersed can- 
 not fail to strike an observing mind with admiration. 
 Who has not listened in a calm and sunny day to the 
 crackling of furze bushes, caused by the explosion of their 
 little elastic pods ; nor watched the down of innumerable 
 seeds floating on the summer breeze, till they are over- 
 taken by a shower, which, moistening their wings, stops 
 their farther flight, and at the same time accomplishes 
 its final purpose by immediately promoting the germina- 
 tion of each seed in the moist earth ? How little are 
 children aware, as they blow away the seeds of dandelion, 
 or stick burs in sport upon each other's clothes, that they 
 are fulfilling one of the great ends of nature! Some- 
 times the Calyx (Involucrum) beset with hooks, forms a bur, 
 as in Arctium Lappa; sometimes hooks encompass the 
 fruit itself, as in Xanthium, and some species of Galium, 
 particularly G. Aparine. Plants thus furnished are ob- 
 served by Linnaeus to thrive best in a rank, manured 
 soil, with which, by being conveyed to the dens of wild 
 animals, they are most likely to meet. The awns of 
 grasses answer the same end. Pulpy fruits serve quad- 
 rupeds and birds as food, while their seeds, often small, 
 hard, and indigestible, pass uninjured through the intes- 
 tines, and are deposited far from their original place 
 of growth, in a condition peculiarly fit for vegetation. 
 Even such seeds as are themselves eaten, like the various
 
 PRESERVATION OF SEEDS AND PRDIT8. 207 
 
 sorts of nuts, are hoarded up in the ground, and occa- 
 sionally forgotten, or carried to a distance, and in part 
 only devoured. Even the ocean itself serves to waft the 
 larger kinds from their native soil to far distant shores." 
 295. Preservation of Seeds and Fruits. It appears 
 that the length of time during which seeds can preserve 
 their vegetative powers, depends in a great measure upon 
 the degree of protection afforded them by their integu- 
 ments ; seeds that have a very thick or hard covering, 
 generally retain their vitality much longer than those in 
 which it is soft or membranous. It does not, however, 
 appear that this circumstance alone is that which deter- 
 mines the durability of vitality in seeds, as some not 
 firmly covered, such as those of the Graminece and 
 Cruciferce, have been known to retain the power of 
 germinating for a long series of years. Seeds of Indian 
 Corn have grown after thirty years, Rye after forty, the 
 Sensitive Plant after sixty, and Kidney Beans, after a 
 hundred years. On turning up ground which has not 
 from time immemorial been under cultivation, many 
 plants are frequently found to spring up, some of them 
 of species different from those growing in the neighbour- 
 hood. From observations made on such occasions, and 
 others of a like nature, it is inferred that a uniform tem- 
 perature, moderate dryness, and exclusion of light, are 
 the conditions most favourable to the preservation of 
 seeds. Various expedients have been tried and suggested 
 for preserving seeds during long voyages, such as putting 
 them into bottles or tin cases, surrounding them with 
 wax or tallow, or burying them in dry clay ; but with- 
 out much success, for most of the seeds of very remote 
 countries seldom survive a protracted voyage, in the 
 course of which they are subjected to great alternations of 
 temperature. The decomposition of fleshy fruits may 
 be prevented for months, by putting them into vessels
 
 208 RECAPITULATION. 
 
 hermetically sealed, from which the air has previously 
 been expelled. 
 
 296. Growth and Reproduction of Mowerless Plants. 
 In such floweiiess plants as resemble in some degree 
 those of the higher classes, we may suppose that the 
 function of assimilation is performed in the same manner 
 as in them. In such other cases as seem to be destitute 
 of the various organs described, the changes subservient 
 to increase in size must take place in the cellular tissue, 
 although in what manner is not apparent. But all these 
 plants differ in being destitute of true seeds, containing 
 reproductive germs, which in becoming developed divide 
 into a descending and an ascending axis. Their sporules, 
 however, are lodged in parts which may be considered 
 as analogous in function to carpels, although they may 
 have no structural resemblance. It is certain that the 
 sporules of Ferns and Mosses act like the seeds of other 
 plants in reproducing individuals of their kind; but they 
 are mere homogeneous masses of matter, and sprout from 
 any point of their surface ; that portion which is exposed 
 to the light shooting out into a stem, and that which is 
 in darkness forming a root. But of the peculiarities of the 
 lower tribes, as the Fungi, Lichens, and Algae, physielo- 
 gists profess an almost entire ignorance. 
 
 RECAPITULATION. 
 
 267. What is meant by Reproduction ? By what two 
 modes are plants naturally propagated ? What are latent 
 buds ? Are plants produced by buds or bulbils in all respects 
 similar to the individuals from which they are derived ? 268. 
 How are buds produced ? Is a branch emanating from a bud 
 a distinct individual ? What is the object of grafting ? What 
 other modes of division are there ? 269. What is meant by 
 Reproduction properly so called ? What organs are subser- 
 vient to it ? Define the seed. Is it a continuation of the
 
 RECAPITULATION. 209 
 
 individual, or a new individual? What are the periods of 
 reproduction ? 270. At what age do plants flower ? In 
 what state are flowers when first distinguishable? 271. 
 What circumstances act as stimuli to flowering? Explain 
 the antagonism which prevails between the reproductive and 
 the nutritive functions. How do you explain the production 
 of double flowers ? How is this antagonism exhibited in the 
 Algse, and in the Fungi ? 272. Do plants differ in the period 
 of the year at which they flower ? Do individuals of the 
 same species differ in the period of flowering ? What advan- 
 tage of this circumstance is taken by cultivators ? How have 
 fruit-trees alternate seasons of productiveness and sterility ? 
 273. What is meant by Elora's Clocks ? 274. What are 
 the functions of the perianth? 275. How is fecundation 
 accomplished? Mention some proofs of the existence of 
 sexes in plants. What happens in the case of the Date Palm ? 
 How are hybrids produced ? 276. Who first brought the ex- 
 istence of sexes into general notice ? What exceptions occur 
 to the action of the pollen ? May the pollen be transmitted 
 to a great distance ? 277. How is the pollen formed ? 
 
 278. How is the pollen protected from moisture ? What 
 contrivances are employed for this purpose in aquatic plants ? 
 
 279. What happens when the pollen is matured ? How is 
 the stigma adapted for receiving the pollen ? How is it dis- 
 persed? Is rain favourable to fertilization ? 280. When 
 the pollen adheres to the stigma, what results ? Is there any 
 uniformity as to the number of pollen-tubes emitted from the 
 pollen-grain ? What are the views of Amici and of Brong- 
 niart as to the action of these tubes ? 281. State the three 
 theories of fecundation. What degree of probability attaches 
 to each ? 282. Explain Schleiden's views. What remark- 
 able conclusion is derived from them? 283. By what argu- 
 ments does Meyen oppose the views of Schleiden ? What is 
 the germ-vesicle ? Of what is it formed ? 284. To what is 
 the germ-vesicle indebted for its nourishment? 285. What 
 is the embryo ? Whence does the funiculus originate ? 286. 
 To what conclusions do the views of Meyen lead ? 287. What 
 happens during the period of maturation? 288. Give an
 
 210 DIRECTION OF THE ORGANS OF PLANTS. 
 
 account of the development of the ovules until the period cf 
 the action of the pollen. What is meant by orthotropous, 
 campylotropous, and anatropous ovules ? 289. Describe the 
 progress of the seed after impregnation. 290. Give an account 
 of the growth of the pericarp. How does thinning the fruit 
 tend to enlarge it ? Do plants vary much with regard to the 
 time occupied in maturing their fruit ? What circumstances 
 accelerate maturation ? 291. What effect have fruits upon 
 the atmosphere ? 292. What chemical changes take place in 
 the fruit ? 293. What is the composition of ripe seeds ? 294. 
 How are seeds dispersed? 295. Do seeds long retain their 
 vitality? What circumstances are favourable to their pre- 
 servation ? 296. Are the functions of growth and reproduc- 
 tion performed in flowerless plants in the same manner as in 
 others ? In what respect are sporules different from seeds ? 
 
 CHAPTER XXIV. 
 DIRECTION OF THE ORGANS OF PLANTS. 
 
 297. General Observations. We know, as a general 
 fact, that terrestrial bodies tending towards a central 
 point, become aggregated so as to produce an integral 
 mass of matter forming the globe of the earth, and to 
 this general fact we give the name of gravitation ; but of 
 the causes and essential nature of gravitation we are 
 ignorant. In like manner, we observe that a plant in 
 germinating shoots a stem upwards into the air, and a 
 root downwards into the ground, and we can perceive the 
 advantages resulting to it from so doing ; but we have 
 not discovered the causes by which it is impelled to per- 
 form these actions. The phenomena are so common and 
 so obvious, that they scarcely attract notice or excite re- 
 flection ; yet philosophers have failed to account for them.
 
 EFFECTS OF GRAVITATION. 211 
 
 Although it is strictly true that stems ascend and roots 
 descend, yet their direction is seldom vertical in the 
 advanced state of the plant. Roots after proceeding 
 downwards, branch out, and run obliquely into the soil, 
 often spreading to a great extent, even farther than the 
 branches ; stems are often inclined, sometimes even pros- 
 trate ; and branches incline in all directions, sometimes 
 even curving downwards. 
 
 298. Effects of Gravitation. Various hypotheses have 
 been adduced to account for the direction of the stems 
 and roots ; but philosophers have usually, as in other 
 puzzling cases, referred it to the action of the vital prin- 
 ciple. It has been supposed by some that gravity is 
 the cause of this phenomenon. Mr. Knight affixed some 
 French beans to the circumference of two wheels, one 
 horizontal, the other vertical, and both kept in constant 
 motion. The radicles of the seed on the vertical wheel 
 extended outwards, the plumules inwards. The seeds on 
 the horizontal wheel sent their radicles downwards, and 
 their plumules upwards ; but the radicles inclined out- 
 wards, and the plumules inwards, and the more so in 
 proportion to the velocity of the wheel. These modifi- 
 cations of direction were obviously producd by the cen- 
 trifugal force obviating the effects of gravity ; but still 
 this does not account for the natural direction of the 
 radicle. Some had supposed that there is an affinity 
 between the root and moisture or darkness. Dutrochet 
 filled with earth a box, in the bottom of which holes were 
 bored. In those holes he placed French beans, and sus- 
 pended the box in the air, at the height of about eighteen 
 feet. The seeds thus received from beneath the influ- 
 ence of the atmosphere and light, and the moist earth 
 was placed above them. Were the cause of the direction 
 of the root its predilection for moist earth, the radicle 
 would ascend ; but this was not the case, for the roots
 
 212 GERMINATION OF THE MISTLETOE. 
 
 shot downwards into the air and soon withered, while the 
 plumules ascended into the soil. It was thus found that 
 there was no affinity between the radicle and the seat of 
 moisture sufficient to counteract its natural downward 
 tendency ; and it was also inferred that no more positive 
 affinity existed between the stems and the atmosphere. 
 
 299. Germination of the Mistletoe. Parasitic plants, 
 or such as strike their roots into the stems of other 
 plants, seem to be exempt from this general tendency. 
 Thus, the seed of the mistletoe, which is enveloped in a 
 slimy substance, will germinate in any direction, upwards, 
 downwards, or laterally. When it happens to fix itself 
 to the upper part of a branch, its radicle will be directed 
 downwards ; but when it is placed on the lower part, the 
 radicle directs itself upwards. M. Dutrochet made it 
 germinate on a cannon ball, when he found that it always 
 directed the radicle toward the centre. Hence, it is 
 obvious, that the tendency of the root of this plant is not 
 towards a medium suited to afford nourishment to the 
 young plant, but that it obeys the attraction of the body 
 on which the seed is fixed, of whatever nature it may be. 
 It is the same with parasitical fungi, and other agamic 
 plants, which do not grow on the ground, but obey the 
 attraction of the bodies to which they adhere. 
 
 300. Effects of Liyht. The radicle of the mistletoe 
 presents another unvarying tendency, that of avoiding 
 light. If seeds of this plant are made to germinate on 
 the inner surface of the pane of a window, all the radi- 
 cles will be seen turning from the light, and projecting 
 toward the interior of the apartment. If placed on the 
 outside of the glass, their radicles will apply themselves 
 to it, as if tending toward the shade. But the stem of 
 this plant does not show the opposite tendency of direct- 
 ing itself towards the light, for its branches are developed 
 indifferently in all directions. Yet the stems of plants
 
 DIRECTION OF THE LEAVES AND FLOWERS. 213 
 
 in general evidently seek the light, as is shown by making 
 them grow in a room, in which light is admitted hy a 
 single aperture, in which case they invariably direct them- 
 selves to it. This has been supposed to be owing to the 
 greater decomposition of carbonic acid on the side next 
 the light, and a greater deposition of carbon on that side, 
 in consequence of which it acquires a greater rigidity, 
 and the other side having more freedom of development, 
 the stem bends. M. Dutrochet infers from this and 
 other phenomena of a like nature, that light is a princi- 
 pal cause of the direction of the organs of plants ; but 
 that those parts only which are green are attracted toward 
 it, while those which are colourless have a contrary ten- 
 dency, insomuch, that colourless stems are known to 
 assume the direction of roots. 
 
 301. Direction of the Leaves and Flowers. The sur- 
 face of the leaf which is next to the upper part of the 
 plant is always directed toward the sky, and this disposi- 
 tion or tendency is so strong, that, if the position of the 
 leaf be inverted, the petiole will become twisted, so that 
 the leaf will recover its natural position. The upper 
 surface of leaves, in general, is more deeply coloured 
 than the lower ; and, as in the case of the stem seeking 
 the light because green, aud the root receding from it 
 because pale, it has been said that the upper surface 
 seeks the light, not because it is the upper surface, but 
 because it is of a deeper green. This law is so constant, 
 that, if the surface of a leaf which is naturally inferior 
 is more deeply coloured than the other, the petiole will 
 become twisted, so as to turn it upwards. The same 
 circumstance is observed in the petals, of which the upper 
 surface is generally more highly coloured. But still it is 
 supposed that the direction of the leaves is not mechani- 
 cally caused by an external agent, but is due to a spon- 
 taneous motion, put in action by the influence of external
 
 214 RECAPITULATION. 
 
 agency. M. Dutrochet took a leaf, and cutting off its 
 petiole, substituted for it a hair, and sinking it by a 
 weight in a vessel of water, exposed it to the light, the 
 lower surface of the leaf being turned toward the window. 
 No alteration in its position took place, although leaves 
 immersed in water under similar circumstances, but with 
 their petioles and stem uninjured, turned towards the 
 light. In many instances, the direction of the flowers is 
 dependent upon mechanical causes. Thus, when the 
 peduncles are slender and feeble, the flowers necessarily 
 droop, as in many Grasses, the Common Bell-flower, and 
 Hyacinths. But the ultimate cause of the directions 
 assumed by flowers, is probably the protection of the 
 sexual organs during the process of fertilization. 
 
 RECAPITULATION. 
 
 297. What is the general direction of the stem ? Do roots 
 always descend perpendicularly ? 298. What is the cause of 
 this direction ? What happened in Mr. Knight's experiment 
 when beans were made to germinate on the circumference of 
 two wheels in motion ? Has the root a special predilection 
 for moisture ? When Dutrochet caused seeds to germinate 
 in holes in the bottom of a suspended box, what happened ? 
 299. State the peculiarity of the Mistletoe as to germination. 
 Is it the same with any other plants ? 300. State the circum- 
 stances showing that the radicle of the Mistletoe tends to 
 avoid the light. How is it shown that stems seek the light ? 
 How has the curvature of a stem toward the light been ac- 
 counted for ? What is M. Dutrochet's general inference on 
 this subject ? 301. If a leaf be inverted, what happens ? 
 What side of a leaf is the greener ? Why is the upper side 
 directed to the light ? Is the direction then entirely caused 
 by light ? What happened when a leaf was sunk in water 
 with a hair substituted for its petiole ? Why do many 
 flowers droop ? What is the probable reason for the direc- 
 tions of flowers ?
 
 METAMORPHOSIS OF ORGANS. 215 
 
 CHAPTER XXV. 
 METAMORPHOSIS OF ORGANS. 
 
 302. Regular Metamorphosis. It has been assumed, 
 in consequence of an extended comparison of plants with 
 reference to the form, arrangement, and mutual transi- 
 tion of their organs, that all the parts appended to the 
 ascending axis are modifications of a single organ, and 
 may he considered as leaves adapted to special purposes. 
 The organs of plants are disposed, so as to constitute 
 several series of whorls of leaves ; and it is found, that 
 in many cases these pass into, or are substituted for, 
 one another. 
 
 303. Leaves, Stipules, and Bracteas. The Leaves, 
 which have already been pretty fully described, may be 
 assumed as the fundamental organs. Appended to, or 
 connected with them, are the Stipules. These organs 
 are not present in all plants. Sometimes they are mem- 
 branous appendages, destitute of vessels, or having a vas- 
 cular fasciculus running up their centre. Frequently, as 
 in Roses, and the Leguminosce, they are in pairs, ap- 
 pended to the base of the leaf-stalk, and have a structure 
 similar to that of the divisions of the leaf, although they 
 may differ in form. Sometimes they have the appear- 
 ance of distinct leaves. They may therefore be consi- 
 dered as rudimentary leaves, or as parts of the leaf. The 
 Bracteas are organs intermediate between the leaves and 
 the sepals. In very many plants the leaves, larger and 
 more divided at the base of the axis of vegetation, become 
 gradually smaller and more simple as they ascend on it, 
 and at length, changing their colour and assuming a more
 
 216 CALYX AND COROLLA. 
 
 membranous structure, appear as bracteas. Here no real 
 distinction can be made between the leaves and the brac- 
 teas. In some Roses the bracteas are exactly similar to 
 the leaves, while in others they are expanded peduncles 
 ' with enlarged stipules. In the garden Tulip, a bractea 
 is often seen at some distance from the flower, which, in 
 texture and colour, partakes of the nature both of the 
 leaf and the sepal. It has been said that bractete differ 
 from leaves, in having no buds in their axillae ; but this 
 is not always the case ; for in viviparous plants, such as 
 Polygonum viviparum, the flowers themselves are con- 
 verted into buds in the axils of the bractese ; Bdlis 
 perennis sometimes bears buds in the axils of the involu- 
 cral leaflets ; and, in the bracteas of Roses, there is 
 always a bud. 
 
 304. Calyx and Corolla. The Sepals, as every one 
 must have observed, very often resemble the leaves in 
 structure and colour, sometimes more or less in form. 
 In Roses, one of the sepals is obviously formed like a 
 leaf, and the rest more or less so. The sepals often dif- 
 fer very little from the bractete, and in many plants these 
 organs are perfectly identical. It has been objected to 
 this assimilation, that the sepals are always verticillate, 
 or come off at the same level, and that they seldom have 
 buds in their axillae ; but, in order that organs should be 
 considered as modifications of each other, it is not neces- 
 sary that they should agree in all their characters. 
 Leaves themselves are frequently verticillate in various 
 degrees, and although they should usually be spirally 
 disposed, they might very naturally be supposed to 
 become verticillate when proceeding from the abrupt 
 termination of the axis or branches. In some cases 
 also, as in Double Tulips, the outer leaves or sepals lose 
 their verticillate arrangement ; and in double Lilies, all 
 the parts of the flower are disposed alternately upon an
 
 THE CARPELS. 217 
 
 elongated axis. The sepals then are leaves reduced to 
 a particular state. 
 
 305. Corolla and Stamens. The corolla is composed 
 of a series of leaves, alternating with those of the calyx, 
 and not always distinguishable from them. In many 
 plants the sepals and petals are alike in colour, texture, 
 and odour ; and when the perianth is single, the sepals 
 and petals seem to be combined. The stamens, when in 
 a single row, alternate with the petals ; or, if opposite to 
 them, may be considered as belonging to a second or inner 
 row. The expansions of the filaments sometimes form 
 petaloid bodies, as in the cup of Narcissus, which, from 
 analogy, is considered as formed of the three outer stamens 
 expanded and united. In the White Water-Lily, the 
 petals gradually diminish in size toward the axis, their 
 margins become altered and assume a yellow colour, and 
 the transition proceeds until we come to the regularly 
 formed stamens. A similar transition is observed in 
 Double Roses, Anemonies, Ranunculuses, Cherries, and 
 Almonds. 
 
 306. Tlie Carpels. In its most simple state, the Car- 
 pel bears the greatest analogy to a leaf, as is seen in 
 the pod of the pea, which resembles a leaf folded upon 
 itself. The same structure is seen in many fruits, of 
 which the carpels are arranged in a verticil, and from the 
 various modifications thus produced are derived the varie- 
 ties of form and internal division of the ovarium, which 
 have already been described, 167, p. 105. Sometimes 
 the pistil reverts to the state of a green leaf, folded 
 upon itself, as in the double Cherry. Frequently also 
 it reverts to the state of petals, as in double Narcissi, 
 Wall-flowers, Ranunculuses, and Saxifrages. It is 
 remarkable, however, that the pistil seldom reverts to 
 the form of the stamen, and that transitions between the 
 stamens and pistils are very rarely met with.
 
 218 CHANGES OF ROOTS AND TUBERS. 
 
 From what has been said above, it appears that all the 
 organs of Flowering Plants are similar in their general 
 plan, graduate into each other, and may be considered as 
 leaves modified for special purposes. The subject is what 
 some have named Morphology, and refers to the natural 
 or normal condition of the organs. 
 
 307. Irregular Metamorphosis. Owing to various 
 circumstances, especially superabundant nourishment, 
 change of soil and climate, and the alteration of the 
 natural condition of plants, they undergo many changes 
 in all their organs. It is probable that every plant has 
 a particular range of distribution, in which, being sub- 
 jected to limited atmospherical influences, it remains 
 unchanged ; but that, when its conditions are materially 
 altered, its form and functions are liable to be modified. 
 In the wild or natural state changes of this kind are 
 rare, while in our gardens and hot-houses they are con- 
 tinually taking place. Of the essential causes of these 
 changes, and the precise manner in which they are 
 effected, it appears that nothing is known with certainty. 
 
 308. Changes of Roots and Tubers. The roots of 
 plants undergo numberless changes. Thus, the wild 
 carrot has a slender tapering fleshy root of a yellowish 
 white colour ; in sandy soil denser, more tinged with 
 yellow, and having an aromatic flavour ; in rich soil, 
 more succulent, whiter, and sweetish. Under cultiva- 
 tion, it increases, becomes much more fleshy, and assumes 
 a deep orange or red colour. The Parsnip varies from 
 fusiform to conical; the Turnip from globular to depressed, 
 turbinate, and fusiform, the epidermis being white, yellow, 
 purple, or partially green. The Potato assumes number- 
 less shapes, being orbicular, oblong, flattened, or curved; 
 and various colours, as white, yellow, red, purple, or 
 variegated ; even its interior becoming sometimes purple 
 or blackish.
 
 CHANGES OF FLOWERS. 219 
 
 309. The Stem and Leaves. Changes of the stem 
 are less frequent. In alpine situations the stem becomes 
 short, and in low and humid situations elongated ; in 
 open pastures firm and coloured, in woods more tender 
 and green. By domestication tall stems are rendered 
 short, and short stems lengthened. The stem of the Wild 
 Cabbage is rather firm and slender, but in a cultivated 
 variety it has become fleshy and fusiform, and in another 
 forms a fleshy tumour above the ground. The changes 
 which leaves undergo are numberless. In some varieties 
 of the Cabbage and Lettuce, for example, they enlarge, 
 become more succulent, and curve inwards, forming what 
 gardeners call a heart. In other varieties, the parenchyma 
 increases more than the veins, and they become puckered ; 
 and again, the margins enlarge more than the disk, 
 when they become curled. Simple leaves assume various 
 marginal alterations, or even become compound ; and 
 compound leaves are sometimes rendered simple, or lose 
 some of their parts, or acquire additional parts. The 
 colours of leaves also undergo many changes. 
 
 310. Changes of Flowers. Changes in the floral 
 organs are extremely common. The petals are increased 
 in number, stamens are converted into petals, the colours 
 of the parts are altered, and their odours modified. The 
 sepals of the tulip, which are six, are multiplied inde- 
 finitely, and assume numberless tints and patterns. Roses, 
 Auemonies, and Ranunculuses, which in the natural 
 state have five petals, acquire an indefinite number. 
 When the petals are increased by an additional whorl 
 or two, the flower is said to be double ; but when the 
 increase is so great, as to destroy the sexual organs, it 
 is said to be full. " With regard to colour," as Pro- 
 fessor Liudley observes, " its infinite changes and meta- 
 morphoses in almost every cultivated flower, can be com- 
 pared to nothing but the alterations caused in the plumage
 
 220 CHANGES IN THE FRUIT. 
 
 of birds, or the hairs of animals by domestication. No 
 cause has ever been assigned for these phenomena, nor 
 has any attempt been made to determine the cause in 
 plants. We are, however, in possession of the knowledge 
 of some of the laws under which change of colour is 
 effected. A blue flower will change to white or red, but 
 not to bright yellow ; a bright yellow flower will become 
 white or red, but never blue. Thus, the hyacinth, of 
 which the primitive colour is blue, produces abundance 
 of white and red varieties, but nothing that can be com- 
 pared to bright yellow; the yellow hyacinths, as they are 
 called, being a sort of pale yellow ochre verging to 
 green. Again, the ranunculus, which is originally of 
 an intense yellow, sports into scarlet, red, purple, and 
 almost any colour but blue. White flowers, which have 
 a tendency to produce red, will never sport to blue, 
 although they will to yellow ; the Roses, for example, 
 and Crysanthemums." 
 
 311. Clianges in the Fruit. These are very common 
 and obvious. The Crab Apple, a small, globular, acid 
 fruit, has, by cultivation, been converted into number- 
 less varieties, differing in size, colour, flavour, and 
 smell. The Sloe, in like manner, has produced the 
 different kinds of plum. The varieties of the Bean and 
 the Pea, and in short of almost all the Plants cultivated 
 for their fruits, or seeds, are endless. In herbaceous 
 plants, these varieties may be propagated by the seeds, 
 but in trees only by subdivision, that is by grafting, by 
 slips, suckers, or layers. 
 
 RECAPITULATION. 
 
 302. Do the organs of plants graduate into each other ? 
 303. Have all plants stipules ? What appearance do the 
 stipules present ? Why may they be considered as rudimen- 
 tary leaves, or as parts of the leaf ? How do leaves graduate
 
 GEOGRAPHICAL DISTRIBUTION OF PLANTS. 221 
 
 into bracteas? What takes place in Roses and Tulips? 
 Have bracteae axillar buds ? 304. Do sepals ever resemble 
 leaves or bracteas ? How do they differ from leaves as to 
 arrangement ? Are leaves ever verticillate ? Are sepals 
 always so? 305. Of what is the corolla composed? Are 
 the sepals and petals ever similar on the same plants ? Do 
 the stamens ever assume the appearance of petals ? Men- 
 tion an instance of the gradation of petals into stamens. 
 
 306. How is a carpel analogous to a leaf ? Mention an in- 
 stance of the pistil becoming a leaf. In what plants does the 
 pistil revert to the state of petals ? What is Morphology ? 
 
 307. What is meant by Irregular Metamorphosis ? How are 
 changes produced in plants ? 308. Mention some instances 
 of changes in the root. 309. What changes take place in 
 the stem ? Are the leaves very liable to change ? What 
 is called a heart ? How are curled leaves produced ? 310. 
 What changes take place in flowers ? What are Double and 
 Full flowers ? Do all colours change into each other ? 311. 
 From what plants are the cultivated apples and plums de- 
 rived? 
 
 CHAPTER XXVI. 
 
 REMARKS ON THE GEOGRAPHICAL DISTRIBUTION 
 OF PLANTS. 
 
 312. General EemarJcs. Botanical Geography, which 
 includes the distribution of plants over the globe, the 
 relative number of families, genera, and species, in dif- 
 ferent districts, the influence of beat, altitude of situa- 
 tion, and soil, the means of dispersion and limitation, 
 together with various subordinate subjects, cannot be 
 here spoken of in full, because a knowledge of the specific 
 forms of plants, and their arrangement into groups, is 
 necessary to him who would enter upon its consideration. 
 But some observations on this important subject may
 
 222 STATIONS OP PLANTS. 
 
 here be made with advantage to the student. If we 
 examine our own country with reference to its vegetation, 
 we find, that many of the plants which occur on the sea- 
 shore are different from those met with in the interior, 
 and that the summits of mountains exceeding 3000 feet 
 in height have a vegetation unlike that of the plains and 
 valleys. Were we to extend our view to other countries, 
 we should find, that although most of the plants of Britain 
 occur in France, while those of the latter country re-ap- 
 pear in Spain, yet that many species are peculiar to each 
 of these regions ; and that countries very distant from 
 each other, as Otaheite and Spitzbergen, have few or no 
 plants in common. 
 
 313. Stations of Plants. The situations in which 
 plants naturally thrive best, considered as to elevation, 
 the nature of the soil, proximity to the sea or to the 
 snow-line, and other circumstances of a like nature, are 
 termed Stations. Of these the following are the most 
 definite : 
 
 1. The Sea. Many plants live immersed in salt water, 
 or float on its surface. Of this kind are most of those 
 forming the family of Algce. They are accordingly termed 
 Marine Plants. 
 
 2. The Sea-shore. Others reside on the borders of 
 the sea, and thrive only when exposed to the influence of 
 the spray and sea-breezes. Of this kind are the Soli- 
 cornice, Glaux maritima, and Arenaria peploides. It is 
 very remarkable, that several plants which grow near the 
 sea occur on the summits of high mountains ; as Statice 
 Armeria, Plantago maritima, and Ehodiola rosea. Plants 
 whose station is the sea-shore are named Maritime. 
 
 3. Fresh water. Some plants live in fresh water, 
 entirely submersed, as Confervce; floating loose on the 
 surface, as Stratiotes ; rooted in the mud, with the leaves 
 and flowers floating, as Nymphoea; or similarly rooted,
 
 STATIONS OF PLANTS. 223 
 
 but with these organs rising above the surface, as Alisma 
 Plantago. Such plants are Aquatic. They are also 
 named Lacustrine when growing in lakes, and Fluviatile 
 when in rivers. 
 
 4. Marshes. Hollow or low grounds partially covered 
 with water, or entirely covered to a small depth, or 
 covered in one season and dry at another, as well as the 
 wet margins of lakes and rivers, ditches, and wet 
 meadows, produce certain plants, as Menyanthes trifoliata, 
 Caltha palustris, Galium uliginosum. Such are termed 
 Palustrine. 
 
 5. Pastures. Meadows, or moist grassy places ; and 
 Pastures, or dry grounds covered with grass. Carda- 
 mine pratensis, Poa pratensis, Senecio Jacobcea. Meadow 
 and Pasture Plants. Pratensine. 
 
 6. Cultivated Lands. Together with pasture plants, 
 this kind of ground produces species introduced by the 
 agency of man. SteUaria media, Spergula arvensis, 
 Agrostemma Githago. Arvensine. 
 
 7. Rocks. Many cryptogamic plants abound on rocks, 
 and a few others prefer them. Old buildings and walls 
 rank with rocks in this respect. Saxifraga hypnoides, 
 CJieiranthus Cheiri. Rupestrine, Murine. 
 
 8. Sands, Sandy or Gravelly Soil. This kind of sta- 
 tion ought to refer to the interior exclusively, but is not 
 definite. Arenaria serpyUifolia. Arenaceous Plants. 
 
 9. Rubbish. Places in the vicinity of dwellings 
 nourish plants, such as the Nettle, which seem to follow 
 man. Ruder al. 
 
 10. Woods. Forests and woods of tall trees. The 
 plants growing in this kind of station are the trees them- 
 selves, and the herbaceous plants which thrive in their 
 shade. Sylvan. 
 
 11. Copses. Thickets, hedges, and bushy places. 
 Shrubs and herbaceous plants. Dumose.
 
 224 HABITATIONS OF PLANTS. 
 
 12. Mountains. Hills and mountains produce nume- 
 rous plants not found in valleys or plains. This head 
 includes upland pastures, mountainous situations, and 
 alpine stations, the latter being those near the line of 
 perpetual snow. Cottine, Montose, Alpine. 
 
 13. Caves. Dark places underground, such as caves, 
 mines, wells, and the like, produce some peculiar plants, 
 which may be called Subterranean. 
 
 14. Plants. Many plants grow on others, whether 
 living or dead, without deriving nourishment from them, 
 and are named Epiphyte; while others, adhering to the 
 surface of plants, extract nourishment from them, and 
 are said to be Parasitic. 
 
 314. Habitations of Plants. The particular kind of 
 situation in which a plant occurs for example, the sea- 
 shore differs from what is technically called its Habita- 
 tion. This latter term is applied to the range of growth 
 of a species, or the extent of the earth's surface, on 
 which it is found in a natural state. It is a remarkable 
 circumstance, that most plants are restricted, not only in 
 longitude, which they might readily be supposed to be 
 from the effects of temperature alone, but also in latitude. 
 Plants of particular species, therefore, do not form trans- 
 verse belts on the earth's surface, but are distributed in 
 irregular patches. Perhaps no plants are of general 
 distribution ; but some have an extensive range, and are 
 found in both hemispheres. But the greater number are 
 restricted within moderate, and many within narrow, 
 limits. It is thus probable that plants have not emanated 
 from original individuals placed in a central district, or 
 in several centres of vegetation, but have been derived 
 from individuals placed originally in particular spots, 
 from which their offspring have radiated until their 
 migrations have been stopped by seas, deserts, moun- 
 tain-ridges, and similar obstacles.
 
 OBSTACLES TO MIGRATION. 225 
 
 315. Circumstances facilitating Migration. The dis- 
 persion of plants appears to take place chiefly by means 
 of the atmosphere. As has already been stated, 294, 
 the seeds of many plants are so small and light that they 
 are easily transported by the winds ; while others are 
 furnished with wings or crowns, which render them 
 lighter by increasing their surface, or they are sur- 
 mounted by tufts, the filaments of which, on separating, 
 serve as levers, to enable them to issue from the pericarp 
 or involucre, find afterwards support them in the air. 
 The minute sporules of cryptogamic plants especially, 
 appear capable of being transported to considerable dis- 
 tances in this manner. Rivers are also a probable means 
 of dispersing seeds, and are known occasionally to carry 
 entire plants from the mountainous regions to the plains. 
 The sea occasionally serves the same purpose in warm 
 climates, but its effects have been greatly overrated. 
 Seeds frequently become entangled in the wool and hair 
 of animals, and may be carried to some distance, while 
 others pass through their alimentary canal uninjured, 
 and may spring up in places remote from that of the 
 parent plant. Man, however, has done more for the dis- 
 persion of plants than all the other animals. Some are 
 accidentally transported by him wherever he extends his 
 migrations, and many have been purposely carried by him 
 to all parts of the globe. 
 
 316. Obstacles to Migration. The ocean presents an 
 obstacle to the migration of plants proportionate to its 
 extent ; for, as salt water is found to destroy the vitality 
 of seeds long subjected to its influence, there is less chance 
 of an interchange of species between lands situated at 
 great distances from each other than between those 
 which are near. Regions covered with arid sand, such 
 as occur on the African continent, may also be supposed 
 to present effectual barriers to the extension of vegeta-
 
 226 INFLUENCE OP SOIL AND MOISTURE. 
 
 tion ; and thus the plants of the western are different 
 from those of the northern and eastern parts of that con- 
 tinent. Elevated mountain-ridges, especially when they 
 rise into the region of perennial snow, have a similar, 
 but less remarkable effect ; for, although the cold of their 
 summits may form a sufficient obstacle, they are inter- 
 sected by ravines and transverse valleys, by which migra- 
 tion may take place. Other circumstances might be 
 mentioned, as forming obstacles to the dispersion of 
 plants ; but the circumstances which have the greatest 
 influence upon it are light, heat, moisture, and the nature 
 of the soil. 
 
 317. Influence of Soil. The chemical nature of the 
 materials of which the soil is composed, appears to have 
 very little influence upon the kind of vegetation which it 
 produces. The same species are found to grow in soil 
 of which carbonate of lime is a principal ingredient, and 
 in that composed chiefly of alumina or magnesian earth ; 
 and maritime plants grow in calcareous as well as in 
 silicious sand ; while alpine species are found on granitic 
 as well as on schistose summits. It is therefore pro- 
 bable, that the degree of disintegration of the materials 
 of which soils are composed, and their capability of 
 retaining moisture, are the circumstances on which their 
 adaptation for particular plants chiefly depends. The 
 degree iu which water is retained in the soil is generally 
 proportionate to the quantity of alumina in it ; and those 
 soils which contain silicious matter in a state of com- 
 minution, most readily give out their moisture. 
 
 318. Influence of Moisture. The different stations 
 of plants above enumerated are differently supplied with 
 moisture ; and different species of plants are differently 
 constituted in this respect. But, beyond a few super- 
 ficial generalizations, it does not appear that much is 
 known on this subject. The greater the supply of mois-
 
 INFLUENCE OF HEAT. 227 
 
 ture, combined with a proportional heat, the greater is 
 the development of vegetation ; and while the arid wastes 
 of Africa scarcely produce any plants, the borders of 
 springs or pools which occur on them are furnished with 
 palms and other plants, which flourish luxuriantly. 
 While the great plains of South America are, during the 
 seasons of drought, converted into regions of sterility, no 
 sooner have the periodical rains fallen than they present 
 an ocean of verdure. 
 
 319. Influence of Heat. As we proceed from the 
 equator towards the pole, we find that the vegetation 
 gradually decreases in vigour ; and, as we ascend from 
 the sea-shore towards the summits of lofty mountains, we 
 observe a repetition of the same circumstance ; until at 
 last, having come to the limits of perennial snow and ice, 
 we find a total cessation of vegetative power. Various 
 forms of vegetation present themselves in different re- 
 gions ; and, in passing from the equator to the pole, we 
 traverse a succession of regions characterized by peculiar 
 plants, insomuch that, although two contiguous regions 
 may not differ very remarkably, the extremes of the 
 series may have no plants in common. As the tempera- 
 ture diminishes in proportion as we ascend a mountain- 
 chain, the vegetation presents itself in belts or zones, 
 certain species being confined within certain limits as to 
 height. But the zones of vegetation observed from the 
 equator to the pole are undefined and interrupted, the 
 species being of varied extent, both as to longitude and 
 latitude. The mean annual temperature, differences in 
 the same latitudes between the heat of summer and 
 winter, and other circumstances, give rise to these irre- 
 gularities, the consideration of which requires a previous 
 knowledge of the families of vegetables, as well as of 
 other subjects not properly belonging to those treated of 
 in this volume.
 
 228 SPECIES, VARIETIES, AND HYBRIDS. 
 
 RECAPITULATION. 
 
 312. What is meant by Botanical Geography ? 313. De- 
 scribe the different stations of plants. 314-. What is meant by 
 Habitation ? 315. What circumstances facilitate Migration 
 of plants ? 316. What are the principal obstacles to the migra- 
 tion of plants ? Has salt water an injurious effect upon seeds ? 
 How do deserts prevent the dispersion of plants ? Do moun- 
 tain-chains present equally insurmountable barriers? 317. 
 Has the chemical nature of the soil much influence on the dis- 
 tribution of plants ? On what circumstances does the adapta- 
 tion of soils for particular plants chiefly depend ? What soils 
 are most retentive of moisture ? 318. What effect does mois- 
 ture produce on the vegetation of the deserts of Africa, and 
 the plains of South America ? 319. What is observed with 
 regard to the vegetation in proceeding from the equator to the 
 pole, and from the sea-level to the summits of mountains ? 
 
 CHAPTER XXVII. 
 SPECIES, VARIETIES, AND HYBRIDS. 
 
 320. General Idea of Species. Although the idea of 
 a Species, or particular kind of plant or animal, is familiar, 
 and generally understood, it is difficult strictly to define 
 the limits of each species, or to form a correct general 
 idea of what is meant by the term. A Lion, a Tiger, 
 an Elephant, a Horse, and a Man, are individuals repre- 
 senting so many species. The particular lion referred 
 to, and all the other lions in the world, constitute the 
 species to which we give the general name of lion ; and 
 so of the others. But, if we examine all the lions in 
 the world, or as many of them as we can find, we may
 
 GENERAL IDEA OF SPECIES. 229 
 
 be induced to conceive that there may be several species 
 of Lions ; for example, the Asiatic Lion, the Barbary 
 Lion, and the Senegal Lion. So also there may be seve- 
 ral species of Elephant ; and in fact, we know two, the 
 Asiatic and the African. Now, if these two Elephants, 
 which differ in characters not remarkably obvious, are 
 yet distinct, are we to consider all such characters always 
 indicative of distinct species ? The Bull-dog, the Shep- 
 herd's Dog, and the Greyhound, differ very considerably 
 from each other. Are they distinct species, or merely 
 varieties of one species ? It is pretty generally agreed, 
 that individual animals which breed together, and pro- 
 duce a fertile progeny, are of the same species. If this 
 opinion be correct, all the domestic dogs are merely 
 varieties of a single species ; the European Man, the 
 Negro, the Malay, the Tartar, and the New Hollander, 
 belong to one and the same species. It is the same 
 among plants. If among them we define a species 
 to be the aggregate of individuals agreeing in all their 
 essential characters, breeding freely together, and pro- 
 ducing perfect seed, which gives rise to similar indivi- 
 duals, also breeding together we may be correct, but 
 our definition is vague, and not applicable in practice, 
 for it is only in very few cases that we can determine 
 species by it. There is nothing absolutely certain as to 
 species, much less as to the groups into which they are 
 disposed, as genera, families, orders, tribes, and the like. 
 We merely agree to consider as species individual plants 
 which closely resemble each other in the structure and 
 form of their organs. Such species, however, often pass 
 into each other by gradations, which render it impossible 
 to draw a line of demarcation, and thus all species are 
 more or less arbitrary. We know from observation, that 
 all assumed species undergo changes from climate, culti- 
 vation, and other influences ; and individuals exhibiting
 
 230 VARIETIES AND HYBRIDS. 
 
 remarkable alterations we call collectively varieties ; but 
 variety is a still more vague idea than species. 
 
 321. Varieties. If we assume that a few individual 
 plants, precisely similar in all respects, and. differing in 
 some respects from all others, were originally created, we 
 should call these plants and their progeny, up to the pre- 
 sent day, a species. Or a single original plant and its 
 offspring would be a species. From various causes, 
 individuals that have been derived from these original 
 individuals may differ considerably from them, and yet 
 be of the same species. Supposing a plant to have been 
 originally, or many individuals of its offspring to be at 
 present, three feet high, with an erect stem, cordate 
 downy leaves, and blue flowers, one or many individuals 
 of the same may be much smaller, with decumbent stem, 
 oblong hairy leaves, and white flowers, although in other 
 more important characters they might agree; such changed 
 individuals would form a Variety. While species, having 
 the normal form and colours, are perpetuated by seed, 
 varieties, although often also propagated in the same 
 manner, are liable to return to the original form, or to 
 deviate into others ; and accidental varieties, originating 
 in cultivation, must be propagated, if it be desirable to 
 preserve them, by grafting, or by slips, or such other 
 means. All species have a tendency to form varieties, 
 insomuch, that no two individuals are ever precisely alike 
 in all respects. The general idea of a variety is thus as 
 vague as that of a species ; and the only correct idea of 
 species would be that which should include every charac- 
 ter or feature common to all the individuals composing it. 
 But our idea of species is derived from the form of the 
 organs merely. In practice, however, we contrive to dis- 
 tinguish species sufficiently for many useful purposes. 
 
 322. Hybrids. Among wild animals, individuals of 
 a species usually have so much aversion from indivi-
 
 HYBRIDS. 231 
 
 duals of another species, that instances of sexual union 
 are extremely rare. Among plants in the same state, 
 although not having instincts and propensities like ani- 
 mals, an intermixture of species is also of very rare 
 occurrence. This probably arises from impregnation 
 having been effected before the pollen from another plant 
 can reach the stigma. But, in a state of cultivation 
 hybridism sometimes occurs, and may readily be induced 
 by art. It is only plants of the same genus, or, at most, 
 of very nearly allied genera, that intermingle in this 
 manner. Even species of the same genus, if very dif- 
 ferent in appearance, cannot be made to produce hybrids. 
 If the anthers of a plant be removed before bursting, and 
 the pollen of another species of the same genus be 
 applied to its stigma, there will be produced seed, which 
 will give rise to individuals having characters partaking 
 of the nature of both parents. The individuals thus pro- 
 duced are capable of performing all the functions of their 
 parents, but they cannot produce seed capable of giving 
 rise to individuals similar to themselves ; for sometimes 
 they are sterile, or become so in a few generations, or the 
 individuals produced by them tend to return to the form 
 of one or other of the parents, and if a hybrid individual 
 be artificially impregnated with the pollen of one or other 
 of the species from which it has originated, it will return 
 to the form of that species. It is possible that some sup- 
 posed species may be mere hybrids, as in the genus Eosa 
 and Rubus; but it seems more probable that, if not species, 
 they are rather varieties than hybrids. There are, how- 
 ever, various instances of hybridism, even in the wild 
 state ; but this accident or circumstance appears to have 
 little general effect in modifying the vegetation of the 
 globe. Although we have no certain data from which 
 we can infer the general permanence of specific forms, 
 yet the considerable number of plants, or parts of plants,
 
 232 EXPERIMENTS IN HYBRIDISM. 
 
 found in the catacombs of Egj r pt, show that the species 
 to which they helong have continued unaltered for more 
 than 3000 years. 
 
 323. Experiments in Hybridism. In 1775, Kolreuter 
 performed some accurate experiments on this subject. 
 He obtained a hybrid from two species of tobacco the 
 Nicotiana rustica, and the N. paniculata which differ 
 greatly in the shape of their leaves, the colour of the 
 corolla, and the height of the stem. The seed ripened, 
 and produced a hybrid, which was intermediate in its 
 characters between the two parents, and which, like all 
 the hybrids reared by this botanist, had imperfect sta- 
 mens. He afterwards impregnated this hybrid with the 
 pollen of N. paniculata, and obtained plants much more 
 resembling the last. This process he continued through 
 several generations, until, by due perseverance, he actu- 
 ally changed the N. rustica into the N. paniculata. His 
 plan of impregnation consisted in cutting off the anthers 
 of the plant intended for fructification, before they had 
 shed their pollen, and then laying foreign pollen on the 
 stigma. This experiment has since been repeated by 
 Wiegmann, who found that he could bring back the 
 hybrids to the exact likeness of either parent, by crossing 
 them a sufficient number of times. This botanist observes 
 that vegetable hybrids, when not strictly intermediate, 
 more frequently approach the female than the male 
 species, but they never exhibit characters foreign to both. 
 
 RECAPITULATION. 
 
 320. Is it difficult to define species ? What is the cause 
 of the difficulty ? What is a species of plants ? Do assumed 
 species often pass into each other ? 321. What is meant by 
 a Variety? Are varieties propagated by seed? 322. What 
 is a Hybrid ? Why are hybrids rare in the wild state ? How
 
 DISEASES OF PLANTS. 233 
 
 may they be artificially produced ? Will any two species of 
 plants produce hybrids ? May hybrids be perpetuated by their 
 seeds ? Are there any reasons for supposing that specific 
 forms are permanent? 323. Describe the experiment per- 
 formed by Kolreuter. 
 
 CHAPTER XXVIII. 
 
 DISEASES, DURATION, DECAY, AND DECOMPOSITION 
 OF VEGETABLES. 
 
 324. Diseases of Plants. r Like animals, plants are 
 subject to deviations from the healthy condition of their 
 organization, but their diseases are less numerous, less 
 complicated, and it may be added, less known. It will 
 suffice here to mention some of the most common forms 
 of disease. 
 
 1. Blanching. A kind of constitutional feebleness, 
 indicated by elongation and slenderness of the stem and 
 branches, incapability of producing, or at least of per- 
 fecting flowers, and a general paleness of the green parts. 
 Moisture, combined with cold, and little sunshine, may 
 be the cause of this disease. 
 
 2. Gangrene. A general languor of the system, flac- 
 cidity of the leaves, and decomposition of them and the 
 twigs ; probably arising from excessive cold, and sub- 
 sequent rapid change to heat. The disease may be 
 general or local. 
 
 3. Canker. According to Professor Lindley, this 
 affection " exhibits itself internally in a brown discoloura- 
 tion of the medulla and parts adjacent, and externally in 
 small brown dead spots, which gradually extend on all 
 sides, until they surround the branch, and kill it. These
 
 234 DISEASES OF PLANTS. 
 
 spots are always dry and hard, never containing any fluid. 
 It is this which is so fatal to many of the apple and pear 
 trees of this country. Its cause and mode of cure are 
 equally unknown. Apparently, healthy shoots will, if 
 grafted on another stock, carry the disease with them." 
 
 4. Carcinoma. As defined by the same author, this 
 " is a disease in which an unusual deposit of cambium 
 takes place between the wood and the bark ; no wood is 
 formed, but instead, the cambium becomes putrid, and 
 oozes out through the bark, which thus separates from 
 the alburnum." 
 
 5. Spotting. The appearance of small black spots on 
 the leaves and parenchymatous parts of plants, with 
 decay of the subjacent substance. 
 
 6. Gumming. A discharge of thick sap through the 
 bark, with drying of the surrounding parts. 
 
 7. Excrescences. By the puncture of insects, excres- 
 cences of various kinds are produced on the leaves and 
 stems of plants, sometimes the calyx, germen, or other 
 parts. The irritation caused by the egg, or by the larva, 
 of the insect, causes a deposition of parenchymatous 
 tissue, which assumes various forms, hut does not affect 
 the general health of the plant, or even that of the neigh- 
 bouring parts. Gall-nuts are produced in this manner. 
 
 8. Smut and Rust. A conversion of the seed or other 
 part of a plant into a granular substance, of a brown, 
 black, red, or yellow colour. 
 
 9. Ergot. An enlargement and elongation of the 
 seeds of grasses, which assume a brown or blackish 
 colour, and contain a powdery, somewhat unctuous sub- 
 stance, producing very deleterious effects on animals 
 which feed on grain intermixed with it. 
 
 Many other diseases, distinguished by fanciful names, 
 and bearing little analogy to the diseases of animals 
 similarly named, might be mentioned. Thus Hypertrophy
 
 LONGEVITY OF TUBES. 235 
 
 is an enlargement of a part, or organ ; Pernio, a wound 
 or ulcer caused by frost ; Exostosis, a " clubbing of the 
 roots." Besides, plants are liable to external injuries of 
 various kinds : Wounds, lopping, fracture, constriction by 
 climbing plants, erosion by animals, and the like. 
 
 325. Duration of Plants. Some species of vegetables 
 exist only a few days, a few weeks, or a few months, and 
 are named annual plants. Other species, which spring 
 up in autumn, survive the winter, produce flowers in 
 summer, perfect their seeds and die in autumn, are 
 named Biennial. Plants of these kinds produce seeds only 
 once in their lives, and so are said to be Monocarpean. 
 Others which last several years, produce fruit more than 
 once, and thus obtain the title of Polycarpean. Of 
 these some last only a few years, while others extend 
 their duration over a long series of years, and many 
 endure for centuries, nay, even thousands of years. These 
 long-living plants are all ligneous, and belong to both 
 divisions of the Embryonate series. 
 
 326. Longevity of Trees. The age of dicotyledonous 
 trees may be satisfactorily ascertained by counting the 
 number of woody layers in a transverse section. But an 
 approximation may be made even in a living tree. The 
 rate at which trees of a particular species increase in 
 diameter, within known intervals, may be determined by 
 measuring the radius, or the diameter, of sections of 
 different individuals, and thus finding the average annual 
 increase. The diameter of a growing tree being ascer- 
 tained, its age may be guessed at by referring to the 
 known rate of increase of the species. Thus, M. De 
 Candolle having ascertained that three yew trees, which 
 were felled, had grown at the rate of a twelfth of an 
 inch in diameter annually for a hundred and fifty years, 
 and that one of them had increased somewhat less rapidly 
 during the next century, applied the rate of growth thus
 
 236 FALL OF THE LEAF. 
 
 obtained to some English yews described by Evelyn and 
 Pennant, one of which, mentioned by the former as 
 growing in Braburn in Kent, in 1666, was fifty-eight feet 
 nine inches in circumference, or 2820 lines in diameter, 
 and therefore as many years old. But this method is 
 liable to objections, inasmuch as trees do not increase 
 uniformly in diameter, some layers being much thicker 
 than others, and trees grow more rapidly in their first 
 years than afterwards. Adanson found that some Baobab 
 trees in Senegal had increased two feet in diameter in 
 two centuries, so that individuals thirty feet in diameter 
 would be 3000 fc years old. But, by ascertaining the 
 height and diameter of young trees of various ages, he 
 came to the conclusion, that a tree twenty feet in diameter 
 would be 2800 years old, and one thirty feet, 5150 years. 
 But, if these arid other methods of estimating the age of 
 trees are not entirely to be depended upon, there can be 
 little doubt that many individuals now living are some 
 thousands of years old, and that some may even be coeval 
 with the human race. 
 
 327. Fatt of the Leaf. Plants having, for a period 
 peculiar to each species, lived, vegetated, and fructified, 
 begin to decay. Even early, in the perennial species, 
 there is a decay of some of the organs. In some, the 
 whole plant dies down to the roots ; in others, the leaves 
 only fall off. The fall of the leaf in autumn has been 
 variously accounted for. It is observed, that in general, 
 the trees whose leaves are earliest expanded are those 
 which lose them first, as is the case with the Lime, Birch, 
 and Plane. The Ash is an exception, its leaves being 
 very late in expanding, and early in falling. Petiolate 
 leaves, and especially those which are articulated upon 
 the stem, are sooner detached than those which are 
 sessile or amplexicaul. In herbaceous plants, the leaves 
 generally decay along with the stem, without falling.
 
 DECAY OF PLANTS. 237 
 
 Although the fall of the leaves usually takes place at the 
 approach of winter, cold is not the cause of the pheno- 
 menon, but rather the interruption to the course of the 
 sap, when vegetation ceases, the vessels of the leaf he- 
 coming dried up. 
 
 328. Decay of Plants. On this suhject Dr. Thomson 
 of Glasgow has the following remarks: "^As long as 
 a plant continues to vegetate, we say it lives ; when it 
 ceases to vegetate, we conclude that it is dead. The life 
 of vegetables, however, is not so intimately connected with 
 the phenomena of vegetation, that they cannot be sepa- 
 rated. Many seeds may be kept for years without giving 
 any symptom of vegetation ; yet, if they vegetate when 
 put into the earth, we say that they possess life ; and, if 
 we would speak accurately, we must say also that they 
 possessed life even before they were put into the earth : 
 for it would be absurd to suppose that the seed obtained 
 life merely by being put into the earth. In like manner, 
 many plants decay, and give no symptoms of vegetation 
 during winter ; yet, if they vegetate when the mild 
 temperature of spring affects them, we consider them as 
 having lived all winter. The life of plants, then, and the 
 phenomena of vegetation, are not precisely the same 
 thing ; for the one may be separated from the other, and 
 we can even suppose the one to exist without the other. 
 Nay, what is more, we can in many cases decide, without 
 hesitation, that a vegetable is not dead, even when no 
 vegetation appears ; and the proof which we have for its 
 life is, that it remains unaltered ; for, we know, that when 
 a vegetable is dead, it soon changes its appearance, and 
 falls into decay. Thus, it appears, that the life of a 
 vegetable consists in two things: 1. In remaining unal- 
 tered, when circumstances are unfavourable to vegeta- 
 tion ; 2. In exhibiting the phenomena of vegetation, 
 when circumstances are favourable. When neither of
 
 238 DECOMPOSITION OF VEGETABLES. 
 
 these two things happens, we may say that a vegetable 
 is dead." These remarks, however, throw no light upon 
 the essential nature of vegetable life, which, it is to be 
 apprehended, we must be content to be ignorant of. 
 " The death of plants, if we can judge from the pheno- 
 mena, is owing to the organs becoming at last altogether 
 unfit for performing their functions, and incapable of 
 being repaired by any of the powers which the vegetative 
 principle possesses. 
 
 329. Decomposition of Vegetables. " The most strik- 
 ing distinction," Dr. Thomson remarks, "between the 
 substances belonging to the mineral kingdom, and those 
 which make a part of animals or vegetables, is, that 
 mineral bodies show little or no tendency to change their 
 nature, and when left to themselves, undergo no spon- 
 taneous decompositions ; whereas animal and vegetable 
 substances are continually altering, and, when left to 
 themselves in favourable circumstances, always run 
 through a regular set of decompositions." During vege- 
 tation the constituents of plants are continually changing, 
 and becoming converted into other substances ; after the 
 death of the plant, this tendency to change exhibits still 
 greater energy. In the spontaneous decomposition of 
 vegetables the specific gravity of the new compounds 
 formed, is almost always less than that of the old body 4 
 Some of them usually fly off in the state of gas or vapour, 
 whence the odour emitted by vegetable bodies during the 
 whole time of their decomposition. When this odour is 
 very offensive, the decomposition is called putrefaction; 
 when not offensive, it is called fermentation ; but the 
 latter term is applied by some to all the stages or degrees 
 of decomposition in vegetables. 
 
 330. Fermentation. Dead vegetable substances con- 
 taining water, and exposed to a moderate or high tem- 
 perature, undergo fermentation. Some vegetable prin-
 
 VINOUS AND ACETOUS FERMENTATIONS. 239 
 
 ciples, as gum, starch, wax, resin, and lignin, though 
 mixed with water, and placed in the most favourable 
 temperature, show little tendency to change their nature ; 
 whereas albumen and fibrine putrify very rapidly. It 
 is when several of the vegetable principles are mixed 
 together that the fermentation is most remarkable. 
 When gluten is added to a solution of sugar in water, 
 the liquid soon runs into vinegar, or, in certain cases, to 
 alcohol and vinegar. When gluten is mixed with starch 
 and water, alcohol and vinegar usually make their 
 appearance ; but the greatest part of the starch remains 
 unaltered. Certain substances also called Ferments, are 
 peculiarly efficacious in exciting fermentation in others. 
 The liquid parts of plants, such as the sap of trees, the 
 juices of fruits, and the decoctions of seeds, roots, or 
 leaves, are those which exhibit this phenomenon in the 
 greatest activity. Three kinds of fermentation are dis- 
 tinguished the Vinous, Panary, and Acetous. Under 
 the name of Vinous Fermentation is included every kind 
 which terminates in the formation of intoxicating liquids. 
 These liquids may be comprehended under two general 
 heads ; those obtained from the decoction of seeds, and 
 those obtained from the juices of plants. The liquids 
 of the first class are denominated Beer or Wash, those of 
 the second Wine. 
 
 331. Vinous and Acetous Fermentations. The farina- 
 ceous seeds of plants being steeped for some time in cold 
 water, are removed from it, and placed in a heap, which 
 after some time is stirred, and then spread out. The 
 seeds, when in the heap, absorb oxygen from the at- 
 mosphere, and convert it into carbonic acid ; the tem- 
 perature gradually rises, and the seeds, which had become 
 dry on the surface, become again moist, and exhale an 
 agreeable odour. Germination takes place to a certain 
 extent, and the kernels undergo a change, their glutinous
 
 240 VINOUS AND ACETOUS FERMENTATIONS. 
 
 and mucilaginous matter being removed, and the texture 
 rendered loose and friable. The seeds are now dried by 
 artificial heat, and ground iu a mill. The Malt thus 
 formed is infused in water at a high temperature, and 
 the liquid obtained is called Wort. This liquid consists 
 of water holding the farinaceous part of the seeds in 
 solution, and is formed of saccharine matter, starch, 
 mucilage, and some other substances. "When sufficiently 
 concentrated by boiling, the wort is put into flat vessels 
 in an open situation, cooled, and then let into deep vessels 
 where, at a favourable temperature, it ferments, the 
 temperature rises, an internal motion takes place, and 
 carbonic acid gas is emitted. By adding a peculiar 
 substance named yeast, of which the essential element 
 appears to be gluten, the temperature rises, carbonic acid 
 is disengaged, and the saccharine matter is converted into 
 alcohol. The sweet liquor obtained from grapes, apples, 
 gooseberries, currants, and the like, is named Must, and 
 that from grapes is composed of water, sugar, jelly, 
 gluten, and tartaric acid. When must is put into a 
 moderately high temperature it ferments, acquires a 
 higher temperature, and emits carbonic acid. In a few 
 days the fermentation ceases, the liquid becomes clear, 
 it has lost its sweet taste, has a less specific gravity, and 
 is known by the name of Wine. This liquid consists of 
 water, alcohol, an acid, extractive matter, and colouring 
 matter. The Acetous Fermentation takes place as fol- 
 lows : Wine or beer kept at a moderately high tempe- 
 rature, with access to the air, gradually becomes thick, 
 acquires a higher temperature, is agitated by an internal 
 motion, and emits a hissing noise. Gradually its motion 
 ceases, filaments attach themselves to the sides and bottom 
 of the vessel, and the liquor, having become clear, is 
 found to be Acetous Acid, or vinegar. 
 
 332. Putrefaction. Vegetable substances exposed to
 
 RECAPITULATION. 241 
 
 the air at a moderate temperature, with access to mois- 
 ture, putrefy, or are decomposed, emitting a disagreeable 
 smell. When moist vegetable matter is accumulated 
 during hot weather, oxygen gas is absorbed and converted 
 into carbonic acid, while the temperature augments, and 
 combustion sometimes takes place. Hay, straw, cotton, 
 and other vegetable matters, have frequently been con- 
 sumed in this manner. When vegetable matters are 
 composed of carbon, hydrogen, and oxygen only, the 
 smell which they emit is not very offensive ; but when 
 azote is present, as in the Cruciferce, they give out a 
 very disagreeable odour ; and still more so, when they 
 also contain sulphur and phosphorus. Lastly, when vege- 
 table bodies putrefy on the surface of the ground, they 
 at last leave a blackish brown powder, to which the name 
 of Vegetable Soil, or Humus, is given. This substance, 
 mixing with the soil, and gradually accumulating, is sup- 
 posed to be subservient to the nourishment of future 
 vegetables. 
 
 RECAPITULATION. 
 
 324. Are plants liable to numerous diseases? What is 
 Blanching? Gangrene? Canker? Carcinoma? Spotting? 
 What effect is produced by the puncture of insects ? What 
 are Smut and Rust? Define Ergot. 325. Do plants differ 
 much in their duration ? What are Monocarpean and Poly- 
 carpean Plants ? 326. How is the age of Dicotyledonous 
 Plants determined ? In what manner may an approximation 
 be made to the age of a growing tree ? What age was attri- 
 buted by Adanson to a Baobab thirty feet in diameter. 327. 
 Give some account of the Fall of the Leaf. To what is it 
 owing ? 328. Is vegetation the criterion of life ? When ve- 
 getation has ceased, or been intermitted, how may we judge 
 that the plant yet lives ? In what two things does the life of 
 a plant appear to consist ? To what is the death of plants
 
 242 RECAPITULATION. 
 
 owing ? 329. What difference exists between minerals and 
 organized bodies as to decomposition? 330. Do vegetable 
 substances vary in the facility with which they decompose ? 
 When gluten is added to a solution of sugar in water, what 
 follows ? What are Ferments ? What is Fermentation ? 
 How many kinds of Fermentation are there P 331. Give an 
 account of the Vinous Fermentation, first, in the decoction of 
 the farinaceous seeds of plants ; secondly, in the juices of 
 fruits. What takes place in Acetous Fermentation ? 332. 
 What is Putrefaction, properly so called ? State some circum- 
 stances relative to it.
 
 SECTION III. 
 
 CLASSIFICATION. 
 
 CHAPTER XXIX. 
 SYSTEM OF LINNAEUS. 
 
 333. General Remarks. The vast number and the 
 diversified forms of plants which each locality presents, 
 suggest the necessity of some arrangement or classifica- 
 tion, by which we may be enabled to distinguish and to 
 name the species which occur to us, to retain their names 
 and characters in our memory, and to communicate to 
 others any points of common interest connected with 
 them. The most superficial observer must have noticed 
 that certain plants have so great a resemblance to one 
 another that they arrange themselves, in the mind of the 
 observer, without any effort of imagination, into natural 
 groups. Thus the Grasses ; the Cruciferous, the Labiate, 
 the Leguminous Plants ; the Ferns, and others, con- 
 stitute as many groups, each with well-marked family 
 resemblances, but no less evidently distinct from all 
 others. Were the natural affinities of all plants as readily 
 perceived as in these groups, the task of distributing them 
 into families would be easy indeed. Such, however, is 
 not the case ; the points by which plants approach or 
 recede from one another are sometimes so indistinct that 
 the learner is liable, in many cases, to be bewildered in 
 the inquiry ; and hence the Natural System the " con- 
 summation devoutly wished for" by every experienced 
 botanist, is apt to alarm the student at the very period
 
 244 GENERAL REMARKS. 
 
 when he requires most encouragement. These difficulties 
 vanish in the Artificial Method of Linnaeus : " the expe- 
 rience of nearly a hundred years," says Sir W. J. Hooker, 
 " has proved to every unprejudiced mind that no system 
 has appeared which can he compared with that of the 
 immortal Swede for \b& facility with which it enahles any 
 one hitherto unpractised in botany to arrive at a know- 
 ledge of the genus and species of a plant." 
 
 334. It is certain that Linnaeus viewed his own method 
 merely in the light of a preface to a great work as the 
 scaffolding of a mighty building. But it is, what pre- 
 faces seldom are, very interesting ; and it is not , what 
 scaffoldings always are, cumbrous and complicated. Its 
 great recommendation is its simplicity ; although it com- 
 prehends all known plants, and is capable of compre- 
 hending all which may hereafter be known, it may be 
 readily understood and remembered by young persons, 
 while it imparts to them a facility and interest in arrang- 
 ing the plants which each locality presents. There is 
 surely no exaggeration in saying that no one of ordinary 
 capacity and liveliness of perception, who will devote an 
 hour or two to the study of the Linnsean method, will 
 fail of understanding and of being pleased with it ; that 
 few who understand and are pleased, will fail to com- 
 mence an active inquiry into the products of the vegetable 
 kingdom, to become collectors of plants ; and that some, 
 at least, will be induced to proceed from the " preface" to 
 the work itself; to advance from the " scaffolding" into 
 the building in other words, to step beyond the limits 
 of an artificial method, and examine the profound and 
 philosophical views developed by the natural system, as 
 expounded in the works of Jussieu, De Candolle, Lindley, 
 and others. Having said thus much of the comparative 
 merits of the artificial and the natural methods of classi- 
 fying plants, it is only necessary to state that the arti-
 
 LINNJEAN CLASSES. 245 
 
 ficial method adopts four degrees of classification the 
 Class, the Order, the Genus, and the Species. 
 
 CLASSES OF THE LINNJEAN SYSTEM. 
 
 335. Classes. In the Linnsean system plants are dis- 
 tributed into twenty-four classes, which are founded upon 
 the number, position, and relative connection of the 
 stamens. To the fanciful eye of Linnaeus, the stamens 
 and the pistils represented sexes the former the male, 
 the latter the female sex. Hence a flower which con- 
 tained both the stamen and the pistil was called herma- 
 phrodite, all other flowers being termed unisexual. Of 
 the twenty-four classes of Linnseus, the first twenty have 
 hermaphrodite flowers ; the next three classes, unisexual 
 flowers ; the last has no flowers. 
 
 336. T\\Q first eleven classes are founded solely on the 
 number of the stamens, and have Greek names, expres- 
 sive of this distinction, the first class being termed 
 mon'andria, the second di'andria, and so on to the tenth, 
 dec'andria. As no flowers are known which have con- 
 stantly eleven stamens, the eleventh class contains those 
 which have twelve, and is, therefore, entitled dodecfandria. 
 But as the genera which have this precise number are 
 few, and as the number is uncertain when the stamens 
 are numerous, all plants are comprehended in this class 
 which have any number of stamens, from eleven to nine- 
 teen inclusive, provided they be disunited. It must be 
 observed that in all these classes the stamens are sepa- 
 rate from the pistil, from the calyx, from the corolla; 
 and that they are of equal or of indeterminate length. 
 
 337. The twelfth and thirteenth classes are founded on 
 the number and the position of the stamens. It is not 
 enough to say that these two classes comprise all those 
 plants which have twenty or more stamens ; the position
 
 246 LINNJEAN CLASSES. 
 
 or insertion of the stamens must be examined. It will 
 be found that the stamens of a rose are inserted into the 
 calyx, while those of a poppy are placed on the recep- 
 tacle or expanded top of the flower-stalk. This is an 
 important distinction, as will appear hereafter ; but it is 
 not expressed in the names of the two classes. The reader 
 must be contented to know that the class icosandria 
 comprises plants with twenty or more stamens inserted 
 into the calyx, while the class polyandria includes those 
 with twenty or more stamens inserted into the receptacle. 
 
 338. The fourteenth and fifteenth classes are founded 
 on the number and relative length of the stamens. Hitherto 
 we have supposed all the stamens to be of the same 
 length, or nearly so ; or, if not, still it has not been 
 observed that there is any regular and determinate pro- 
 portion in their length. This character is now to be con- 
 sidered: 1. If a flower of the dead-nettle be examined, 
 the first thing that strikes the eye is the presence of four 
 stamens ; but the plant does not belong to the fourth 
 class, for the stamens are arranged in one row, the inner 
 pair being distinctly and constantly shorter than the 
 outer pair. 2. If the blossom of a wall-flower be 
 examined, it is immediately seen that it contains six 
 stamens ; but the plant does not belong to the sixth 
 class, for two of the stamens are shorter than the rest, 
 and solitary, while four are larger and in pairs. To 
 express these characters the terms didynamia and tetra- 
 dynamia are employed, the former denoting that two, 
 the latter that four stamens are stronger, because longer 
 than the rest. 
 
 339. The sixteenth, seventeenth, and eighteenth classes, 
 are founded on modes of connection subsisting between 
 the filaments of the stamens. Hitherto all the stamens 
 have been free, separate, disunited ; but if a plant occur 
 in which the stamens are united by their filaments,
 
 LINN^EAN CLASSES. 247 
 
 while their anthers are disunited, it will certainly belong 
 to one of the next three classes. 1 . Let a flower of the 
 common mallow be examined ; the stamens are numerous, 
 or, as they are usually called, indefinite ; but the plant 
 is neither icosandrous nor polyandrous, nor is there any 
 occasion to look for the insertion of the stamens. A new 
 character at once presents itself all the filaments ot 
 the stamens are united into one set, forming one regular 
 membrane or tube below, while the anthers are free 
 above. The fanciful mind of Linnaeus saw in this com- 
 bination a brotherhood, and he expressed it by the Greek 
 word "adelphia." The class monadelphia, therefore, 
 includes plants whose stamens are united by their fila- 
 ments into a tube. 2. Now, let a flower of the common 
 clover be inspected. Here the stamens are, indeed, 
 definite there are ten ; but the plant does not belong 
 to the tenth class, nor is it necessary to count the 
 stamens, for it is instantly apparent that the filaments 
 are combined. At first sight they seem to be monadel- 
 phous ; but, upon closer examination, it will be found 
 that nine of the stamens are united and one is free. 
 Although it may fairly be questioned how unity can 
 express brotherhood, yet two sets, two brotherhoods are 
 here supposed, and the class is called diadelphia. The 
 difficulty will vanish before the imagination. 3. Lastly, 
 let a flower of St. John's wort be examined. Here are 
 stamens indefinite, sometimes definite; but it matters 
 not, there is no occasion to count them ; the filaments 
 are obviously combined, and that is sufficient. But in 
 this case we have three sets, or five sets, or more ; and 
 the class has accordingly received the name polyadelphia. 
 340. The nineteenth class is founded on the connection 
 of the anthers of the stamens ; in this case the filaments 
 are free, while the anthers are united into a tube. This 
 class is called syngenesia, but the term is not sufficiently
 
 248 LINNJEAN CLASSES. 
 
 precise ; it denotes merely a growing together, without 
 defining the parts of the organ which exhibit the phe- 
 nomenon. The term synaniherous would satisfy every 
 wish. After all, the flowers of this class are very small, 
 and the character just mentioned is not very striking ; 
 it may, therefore, be added that the flowers are called 
 compound, and this one word is sufficient to overcome 
 the whole difficulty connected with the subject, after a 
 single examination of a plant of this class. We said 
 "are called" compound, and we said so advisedly, for 
 they are not compound; but we must not be too critical; 
 the terms "compound" and "composite" are always 
 applied to syngenesious plants, and vice versd, and with 
 this we must be satisfied for the present. 
 
 341. The twentieth class is founded on the connection 
 subsisting between the stamens and the pistil. Though 
 in the last four classes the stamens have been in some 
 sort united, yet in these, as well as in all the preceding 
 classes, they have been entirely separate from the pistil, 
 so that the one organ might be removed without inter- 
 fering with the other. But if a flower, as of an orchis, 
 presents an arrangement which renders this impossible, 
 owing to the stamens being situated upon the style or 
 column of the pistil, above the germen or ovary, a new 
 characteristic occurs, for which the term gynandria has 
 been adopted a term compounded of the two Greek 
 words, respectively employed to designate the pistil and 
 the stamen. 
 
 342. The twenty-first, twenty-second, and twenty-third 
 classes are founded on modifications arising from uni- 
 sexuality and hermaphroditism. These expressive terms 
 must now be simply explained. Hitherto, we have been 
 concerned with such plants only as have flowers with 
 both stamens and pistils ; these are called hermaphrodite 
 flowers, from their containing the two reproductive organs
 
 LINN2EAN CLASSES. 249 
 
 the stamen, symbolized by the Greek Hermes, the 
 pistil by the Greek Aphrodite. 1. But a plant may 
 occur, as a spurge or a sedge, of which some of the 
 flowers contain stamens without pistils, others pistils 
 without stamens ; such flowers are said to be unisexual, 
 and they may, for the sake of convenience, be called 
 respectively staminiferous and pistuliferous. To include 
 all plants presenting this peculiarity Linnaeus adopted 
 the term moncecia a Greek word simply meaning one 
 house. Of course the individual plant is the house ; each 
 flower is viewed as an apartment ; Hermes and Aphrodite 
 are in the same house, but always in separate apartments. 
 2. But the estrangement may proceed further. The 
 staminiferous and the pistilliferous flowers may be not 
 merely separate from each other, but always found on 
 distinct plants of the same species, as in the poplar and 
 the hop. This class of plants is designated by the term 
 diceda, signifying two houses Hermes in one, Aphrodite 
 in the other. 3. There is yet another case : there may 
 be plants in which the peculiarities of the two preceding 
 classes are combined, with an additional character : 
 stamens and pistils may occur separate or united, on 
 the same or on different plants ; in other words, com- 
 plete and incomplete flowers, hermaphrodite and uni- 
 sexual flowers may occur on the same plant, or on 
 different plants of the same species. To the class which 
 comprises such unusual associations the term polygamia 
 has been devoted. 
 
 343. The twenty-fourth class is founded on the absence, 
 or the obscure nature of the reproductive organs, as 
 compared with those of all the other classes. Linnaeus, 
 in whose playful fancy the vegetable world shadowed 
 forth the relations of the animal, dignified the twenty- 
 three classes above described as consisting of phanero- 
 gamic plants plants in which the essential organs of
 
 250 LINN J3 AN CLASSES. 
 
 reproduction are obvious to our senses ; the last class, 
 therefore, in which all is mystery, is designated hy a 
 term which simply suggests our ignorance, viz., crypto- 
 gamia; plants in which the organs of reproduction are 
 concealed. These are the ferns, the mosses, the fungi, 
 the sea-weeds. Among the last of these plants are found 
 certain equivocal heings, which serve to connect together 
 the animal and the vegetable kingdoms ; they seem to 
 belong indisputably to neither ; sometimes they assume 
 the characters of both ; at other times, indifferently of 
 either. Their germs take root and grow like plants, 
 while their fruit seems to be possessed of voluntary 
 motion, and to pass through a stage of animal exist- 
 ence, before it again takes root and produces another 
 generation. 
 
 344. The foregoing remarks are thus condensed : 
 
 CLASS 
 
 1. MONANDEIA 1 Stamen in each flower. 
 
 2. DIANDRTA 2 Stamens, equal in length. 
 
 3. TRIANDEIA 3 
 
 4. TETEANDRIA 4 
 
 5. PENTANDEIA 5 
 
 ll 
 
 SOI 
 M 
 
 -^ 
 P 
 
 6. HEXANDRIA 6 
 
 7. HEPTANDRIA 7 
 
 8. OCTANDRIA 8 
 
 9. ENNEANDRIA 9 
 
 10. DECANDRIA 10 
 
 11. DODECANDRIA 12 to 19 
 
 12. ICOSANDRIA 20 or more, inserted into the calyx. 
 
 13. POLYANDRIA 20 or more, inserted into the receptacle. 
 
 14. DTDYNAMIA 4; 2 long, 2 short. 
 
 15. TETRADYNAMIA 6; 4 long, 2 short; flowers cruciform. 
 
 16. MONADELPHIA Filaments united at the base into one set. 
 
 17. DIADKLPHIA Filaments united into two sets. 
 
 18. POLYADELPHIA Filaments united into three or more sets. 
 
 19. SYNGKNESIA Anthers united. Flowers compound. 
 
 .20. GYNANDEIA Stamens inserted on the Pistil. 
 
 CLASS 
 
 21. MONCECIA Stamens and Pistils in separate flowers on the 
 
 same plant. 
 
 22. DICECIA Stamens and Pistils in separate flowers on two 
 
 separate plants. 
 
 23. POLYGAUIA Stamens and Pistils separate in some flowers, 
 
 united in others, either on the same plant, or 
 two or three distinct plants. 
 
 24. CRYPTOGAMIA Fructification concealed.
 
 LINNJ3AN CLASSES. 
 
 251 
 
 345. The classes of the Linnsean system may also be 
 conveniently studied in the following table : 
 
 c8 eS 
 
 1 jlllllllii II || If 
 
 .5-El3J-|" |-3 f^ 1
 
 252 MNN^AN ORDERS. 
 
 ORDERS OF THE LINN2EAN SYSTEM. 
 
 346. The twenty-four classes of LinnsBus are hu- 
 morously designated by Rousseau as " twenty-four regi- 
 ments," which must now be divided into their respective 
 companies. "If," he observes, "you have patience to 
 make a regular progress ; to throw this multitude into 
 large bodies ; to subdivide these into smaller ones, and 
 these again into others so small as to command them 
 well with the eye, you have at length a regular army, 
 which you can number, arrange, and discipline at your 
 pleasure." To drop the military metaphor, we no.w 
 proceed to divide the Classes into Orders a task, perhaps, 
 as agreeable as the former, though certainly less difficult. 
 Generally speaking, knowledge loses half its charm when 
 it can be acquired without difficulty. The orders of the 
 first thirteen classes are founded on the number of the 
 styles, or of the stigmas, when these are sessile ; and, as 
 every one can count styles or stigmas as easily as he can 
 count stamens, the only tax on the memory is to fami- 
 liarise it with the following terms, in which the word 
 gynia, or pistil, is substituted for the word andria, or 
 stamen. These are the orders : 
 
 1. Monogynia, 1 style. 6. Hexagynia, 6 styles. 
 
 2. Digynia, 2 styles. 7. Heptagynia, 7 styles. 
 
 3. Trigynia, 3 styles. 8. Octogynia, 8 styles. 
 
 4. Tetragynia, 4 styles. 9. Decagynia, 10 styles. 
 
 5. Pentagynia, 5 styles. 10. Poly gynia, many styles. 
 
 347. After the first thirteen classes the styles are no 
 longer used for the purpose of subdividing the classes 
 into orders. In the fourteenth class, didynamia, such 
 a principle of subdivision would be utterly useless, because 
 all the flowers belonging to this class have one pistil, and 
 no more. Here Linnaeus had recourse to another circum-
 
 LINN.EAN ORDERS. 253 
 
 stance, which, though founded in error, has furnished 
 one among the many proofs that successful error is not 
 unpopular. The four little bodies, or prominences, 
 which may he seen at the bottom of the calyx of the 
 dead-nettle, and of most labiate plants, were mistaken 
 by Linnzeus for " naked seeds," seeds without a pericarp. 
 Seeds they are not, but they are the four lobes of a 
 deeply-divided pericarp, which contains four small nuts. 
 But "the error remains, and is likely to remain, in the 
 word gymnospermia, which is employed to distinguish all 
 such plants in this class from those furnished with a peri- 
 carp which no one can mistake, and which are, therefore, 
 called angtiospermia. The plants composing the latter 
 order have a two-celled pericarp, or capsule, containing 
 an indefinite number of seeds. The orders of the four- 
 teenth class may, then, be briefly described, as founded 
 on the presence, or (supposed) absence, of a seed- 
 vessel : 
 
 1. Gymnospermia ; seeds 4, apparently naked ; or 
 more correctly, ovary 4-lobed. 
 
 2. Angeiospermia ; seeds in a distinct pericarp. 
 348. In the fifteenth class, tetradynamia, the flowers 
 
 have also one pistil, and no more. Here the ordinal 
 characters are again taken from the fruit. There are 
 two familiar garden plants, wall-flower, and candy-tuft ; 
 the fruit of the former is long and narrow, that of the 
 latter short and relatively broad. The former fruit is 
 called a siliqua, the latter a silicula. It is desirable to 
 avoid the word pod, because it is commonly applied to 
 the legume of the pea and the bean. An ordinal cha- 
 racter derived from the comparative length of a seed- 
 vessel may appear trivial, and it may be sometimes hard 
 to draw the line ; but it is popular, and will rarely 
 deceive. We have, then, the fifteenth class, divided into 
 the following orders:
 
 254 LINN2EAN ORDERS. 
 
 1. Sttiquosa ; seeds in a long seed-vessel, or siliqua. 
 
 2. Siliculosa ; seeds in a short seed-vessel, or sUicula. 
 
 349. In the sixteenth, seventeenth, and eighteenth 
 classes, monadelphia, diaddphia, and polyaddphia, the 
 orders are founded on the number of stamens which com- 
 pose each adelphia, or brotherhood. Here there is no 
 difficulty ; and, what is very pleasant, no new terms are 
 required to burden the memory. The orders, accord- 
 ingly, of these three classes are the following: 
 
 1. Triandria, 3 stamens. 
 
 2. Pentandria, 5 stamens. 
 
 3. Decandria, 10 stamens. 
 
 4. Polyandria, many stamens. 
 
 350. The orders of the nineteenth class, syngenesia, 
 are founded on the strudure of the flower, and here, for 
 the first time, attention is required. Let the student 
 take a head of flowers from the three following plants, 
 the dandelion, the daisy, and the blue-bottle: 1. On 
 examining the dandelion, he will find that each floret 
 presents a "strap-shaped corolla, tubular at the base, 
 then slit on one side, so that the limb becomes flat ;" 
 through the tubular part of the corolla five stamens 
 arise, with cohering anthers ; and through the tube of 
 the anthers arises the style with its cleft stigma ; the 
 whole is mounted upon the pistil. This structure is 
 found in each floret of this plant : each floret is strap- 
 shaped ; each contains pistil and stamen ; in a word, all 
 the florets are equal, and hence all the plants which have 
 equal and perfect florets belong to an order named 
 cequalis. 2. But the daisy, when examined, is found to 
 present two kinds of floret, differing in structure : those 
 of the margin, or circumference, are strap-shaped, while 
 those in the centre are tubular ; the latter, or flowers of 
 the disk, as they are called, are perfect, being furnished 
 with both pistil and stamen ; while the former, or flowers
 
 LINN^AN ORDERS. 255 
 
 of the ray, have a pistil, but no stamen. These, then, 
 being imperfect, seem to be superfluous ; and, hence, to 
 all plants so characterized, the ordinal designation of 
 superflua has been applied. 3. The blue-bottle exhibits 
 a further modification : the florets of the disk are per- 
 fect, while those of the ray contain neither pistil nor 
 stamen ; they seem to be of no use, and to them the 
 term frustranea has been devoted. Thus, we have the 
 following orders : 
 
 1. ^Equalis; all the florets perfect. 
 
 2. Superflua; florets of the disk perfect; those of 
 the ray pistilliferous only. 
 
 3. Frustranea; florets of the disk perfect; those of 
 the ray, neuter. 
 
 351. " We have now," says Rousseau, "happily, I 
 hope, passed the fool's bridge, and are arrived safely on 
 the other side, where the way is plain, and we shall soon 
 get pleasantly to the end of our stage." The orders of 
 the three following classes are founded on the number, 
 union, and situation of the stamens, and take their names 
 accordingly from the foregoing classes. Thus the twen- 
 tieth class, gynandria, is divided into the orders monan- 
 dria, 1 stamen; diandria, 2 stamens; heocandria, 6 
 stamens. The twenty-first class, moncecia, in which the 
 stamens and pistils are in separate flowers on the same 
 plant ; and the twenty-second class, dioxia, in which the 
 stamens and pistils are in separate flowers and on differ- 
 ent plants, are both distinguished into orders by the 
 well-known principles conveyed by the terms monandria, 
 1 stamen; diandria, 2 stamens; monadelphia, stamens 
 combined, <fec. 
 
 352. The twenty-third class, polygamia, has three 
 orders, founded on the three modes in which the three 
 sorts of flowers are arranged in the same plant, or in
 
 256 LINN JB AN ORDERS. 
 
 two plants, or in three. The names, which are familiar, 
 are as follows: 
 
 1. Moncecia; unisexual flowers accompanied by barren 
 or fertile flowers, or both ; all on one plant. 
 
 2. Dicecia; the same, on two different plants. 
 
 3. Triceda ; the same, on three different plants. 
 
 353. In the twenty-fourth class, cryptogamia, in which 
 the organs of fructification baffle our theories, and even 
 our sight, the plants have a very particular structure, 
 which serves to furnish not only classical characters, 
 but also ordinal subdivisions ; the latter are, in fact, 
 natural orders, or families. These are 
 
 1. Ferns. 2. Mosses. 3. Lichens. 
 4. Fungi. 5. Algae. 
 
 ORDERS OF THE LINNEAN SYSTEM. 
 
 354. 1. The Orders of the first thirteen classes are 
 founded on the number of styles: 
 
 1. Monogynia, 1 style. 6. Hexagynia, 6 styles. 
 
 2. Digynia, 2 styles. 7. Heptagynia, 7 styles. 
 
 3. Trigynia, 3 styles. 8. Octogynia, 8 styles. 
 
 4. Tetragynia, 4 styles. 9. Decagynia, 9 styles. 
 
 5. Pentagynia, 5 styles. 10. Polygynia, many styles. 
 
 2. The Orders of the fourteenth class are two, founded 
 on the presence or (supposed) absence of a seed-vessel: 
 
 1. Gymnospermia ; seeds 4, apparently naked; or ovarium 
 
 4-lobed. 
 
 2. Angeiospermia ; seeds in a distinct seed-vessel. 
 
 3. The Orders of the fifteenth class are two, founded 
 on the comparative length of the seed-vessel: 
 
 1. Siliquosa; seeds in a long seed-vessel, or siliqua. 
 
 2. Siliculosa; seeds in a short seed-vessel, or silicula.
 
 LINN^EAK ORDERS. 257 
 
 4. The Orders of the sixteenth, seventeenth, and 
 eighteenth classes are founded on the number of stamens 
 in each adelphia, or brotherhood : 
 
 1. Triandria, 3 stamens. 2. Pentandria, 5 stamens. 
 3. Decandria, 10 stamens. 4>. Polyandria, many stamens. 
 
 5. The Orders of the nineteenth class are founded on 
 the structure oj 'the flower ': 
 
 1. jEqualis; all the florets perfect. 
 
 2. S'liperftua; florets of the disk perfect; of the ray, pis- 
 
 tilhferous only. 
 
 3. Frustranea; florets of the disk perfect ; those of the ray, 
 
 neuter. 
 
 6. The Orders of the twentieth class are founded on 
 the number of the stamens: 
 
 1. Monandria, 1 stamen. 2. Diandria, 2 stamens, &c., &c. 
 
 7. The Orders of the twenty-first and twenty-second 
 classes are founded on the number, union, and situation 
 of the stamens: 
 
 1. Monandria, 1 stamen. 2. Diandria. 2 stamens. 
 
 3. Monadelphia, &c. 
 
 8. The Orders of the twenty-third class are three, 
 founded on the separation of the sexes in the same plant, 
 or in different plants : 
 
 1. Moncecia; unisexual flowers accompanied by barren or 
 
 fertile flowers, or both, all on one plant. 
 
 2. Dicecia ; the same, on two different plants. 
 
 3. Tricecia; the same, on three different plants, 
 
 9. The Orders of the twenty-fourth class are natural 
 orders or families: 
 
 1. Filices. 2. Musci. 3. Hepaticce. 4. Lichens. 
 5. Fungi. 6. Aloee. 
 
 */ ? 
 
 355. Genus; Species; Variety. 1. The classes hav- 
 ing been divided into orders, the next step in classifies-
 
 258 RECAPITULATION. 
 
 tion is to distribute the orders into genera. A genus is 
 an assemblage of species, which present an obvious 
 resemblance in the organs of fructification. Thus, the 
 water ranunculus is a species with white flowers, the 
 pilewort ranunculus has yellow flowers; the leaves of 
 these two species differ considerably ; the one grows in 
 water, the other in meadows ; yet they agree in the 
 general character of their fruits ; and there are fourteen 
 or more species of ranunculus, which differ from one 
 another in the forms of their leaves, and in various other 
 matters ; but all agree in the structure and arrangements 
 of their fruits, and hence they constitute the universally 
 recognised genus ranunculus. 2. As an order consists 
 of genera, so a genus consists of species. A species is a 
 collection of individuals, which present similar characters, 
 and reproduce themselves with the same essential proper- 
 ties and qualities. Each individual water ranunculus 
 resembles every other water ranunculus, more nearly 
 than it resembles any other plant ; we hence infer that 
 they all sprang from a common stock, and are enabled 
 to preserve their characters unchanged when propagated 
 by seed. 3. A variety is an individual of the same species, 
 presenting the same essential characters, but differing in 
 some points, from accidental circumstances of little im- 
 portance, as climate, soil, temperature, &c. These cir- 
 cumstances affect the size, the colour, or other unimportant 
 characters of plants, without affecting the specific cha- 
 racters. When the particular cause ceases to operate, 
 varieties generally revert to the common characters of 
 the species.. 
 
 RECAPITULATION. 
 
 333. What groups of plants present obvious family resem- 
 blances ? 334. What are the advantages of the Linnaean 
 system ? 335. On what principle did Linnaeus distribute
 
 THE NATURAL SYSTEM. 259 
 
 plants into classes and orders ? 336. On -what principle are 
 the first eleven classes founded? 337. What is the precise 
 distinction between the twelfth and thirteenth classes ? 338. 
 How are the fourteenth and fifteenth classes distinguished ? 
 339. Explain the distinction of the sixteenth, seventeenth, 
 and eighteenth classes. 340. How is the nineteenth class 
 characterized ? 341. State the peculiarities of the twentieth 
 class. 342. What modifications are observed in the twenty- 
 first, twenty-second, and twenty-third classes ? 343. What is 
 the principal character of the twenty-fourth class ? 346. How 
 are the first thirteen classes distributed into orders ? 347. 
 How is the fourteenth class divided? 348. How is the 
 iifteenth distinguished? 349. What divisions occur in the 
 sixteenth, seventeenth, and eighteenth ? 350. Explain the 
 orders of the nineteenth class. 351. Describe the ordinal 
 characters of the twentieth, twenty-first, and twenty-second 
 classes. 352. Explain the distinction of the twenty-third 
 class. 353. How is the twenty-fourth class divided into 
 groups? 355. What is a genus, a species, and a variety of 
 plants ? 
 
 CHAPTER XXX. 
 THE NATURAL SYSTEM. 
 
 356. General Remarks. 1. The divisions of plants 
 adopted in the system of Jussieu, commonly called the 
 Natural System, are not founded, like those of Linnaeus, 
 upon the number and modifications of a single organ, 
 but upon the characters presented by all parts of plants 
 collectively. On this principle, plants are grouped to- 
 gether which have a greater relation to those which 
 immediately precede or follow them, than to any other. 
 2. Nature appears to have suggested such a system, in 
 having stamped on many plants a marked character of
 
 260 SPECIES, GENUS, ORDER, ETC. 
 
 structure : the Graminese, the Labiatse, the Cruciferas, 
 the Compositse, the Umbelliferee, present well-defined 
 physiognomical characters ; these groups of plants have, 
 consequently, been always severally combined, except 
 when their relations have been sacrificed to an artificial 
 scheme. 3. The advantages of the Natural System are 
 found in the general and philosophical ideas, which we 
 are led to form from a comprehensive view of the entire 
 vegetable kingdom. The affinities of plants are thus 
 determined by a consideration of all the points of 
 resemblance which occur in their various parts, pro- 
 perties, and qualities ; and, consequently, the struc- 
 ture and quality of an imperfectly known plant may 
 be determined by those of another which is well 
 known. 
 
 357. Species, Genus, Order, Class. The distinctive 
 meanings attached by botanists to the terms Species, 
 Genus, and Variety, have been already explained, f 355, 
 and to that paragraph the reader is referred. Orders, 
 or natural families, are formed of genera, as these are of 
 species, and are founded on characters presented by all 
 parts of plants the seed, the fruit, the flowers, and the 
 vegetative organs. The superficial observer little sup- 
 poses that all the species of Ranunculus, all those of 
 Anemone, all of Helleborus, all of Aquilegia, Aconitum, 
 and several other genera, are members of the family 
 typified by the Ranunculus, and hence called Ranuncu- 
 laceous plants. Classes are the first division, and they 
 consist each of a certain number of orders or natural 
 families, united by a character more general and com- 
 prehensive, but always proper to each individual in the 
 class. It is not pretended that there are any such posi- 
 tive arrangements in nature as genera and families. 
 Nature creates only individuals; in these, the general 
 organization is so modified, as to pass, by almost in-
 
 DIVISIONS OF JUSSIEU. 261 
 
 sensible gradations, from the simplest to the most com- 
 plicated structure. Observation has led to the discovery 
 that many plants reproduce themselves constantly by 
 seeds; this succession, viewed in an abstract and general 
 manner, determines a species. Observation has further 
 led us to classify a large number of species, differing 
 from one another in certain points, but agreeing in some 
 common characters, as of internal structure, into a group, 
 which we call genus. By extending this principle of 
 association, we arrive at natural families, or orders, 
 founded on resemblances in all points of their organiza- 
 tion. But these classifications have no positive existence 
 in nature; they are the works of man. A natural family, 
 then, is merely an assemblage of plants in which the 
 species or genera form a kind of uninterrupted succes- 
 sion ; in which the general organization passes insen- 
 sibly from individual to individual, without any shock 
 to disturb the harmony of nature. In this sense only 
 can the term be applied to the systematic divisions of 
 man. 
 
 358. Divisions of Jussieu. The primary divisions are 
 founded on the separation, the combination, and the 
 absence of the petals, and are termed the polypetalous, 
 the monopetalous, and the apetalous groups ; to which is 
 added a fourth, founded on the separation of the sexes in 
 flowers having no petals, and termed diclinous. The first 
 three are divided with reference to the insertion of the 
 stamens, which are epigynous, perigynous, or hypogynous ; 
 further, the monopetaloua epigynous group is subdi- 
 vided into plants which have their anthers united, and 
 those which have them distinct. Hence we have eleven 
 
 claSS6S : ~ Class. 
 
 C Stamens epigynous 1 
 
 Polypetalous < Stamens perigynous 2 
 
 ( Stamens hypogynous 3 t
 
 262 DIVISIONS OF DE CANDOLLE. 
 
 Class. 
 
 f Corolla hypogynous 4 
 
 Mononptalous ) C r lla P eri g vnous 5 
 
 jyiUilUUGlalUUb < /" A j_i *j_ i r 
 
 inn- \ Anthers united o 
 
 / Corolla epigynous \ . ,, -,. ,. , 
 V (_ Anthers distinct 7 
 
 f Stamens epigynous 8 
 
 Apetalous . . < Stamens perigynous 9 
 
 ( Stamens hypogynous 10 
 
 Diclinous 11 
 
 359. Divisions of De CandoUe. De Candolle reduced 
 the eleven classes of Jussieu to four ; the first three being 
 founded on the separation or cohesion of the several parts 
 of the flower, the fourth on the suppression of the floral 
 envelopes. Thus, in Thalamiflorse, all the parts are pre- 
 sent and distinct from each other ; in Calycifloraj, the 
 stamens adhere to the calyx ; in Corolliflorse, the petals 
 cohere with each other ; in Monochlamydese, the corolla 
 is suppressed, and, in the most imperfect orders, the calyx 
 also. 
 
 Polypetalous ( Stamens hypogynous . Thalamiflor<e. 
 1V \ Stamens perigynous . Calycifiorae. 
 
 Monopetalous Corolliflorae. 
 
 Apetalous Monochlamydea. 
 
 360. Relative Value of Characters. In order to 
 establish a correct classification of plants into natural 
 families, the relative value of the characters must be 
 determined. In examining carefully a certain number of 
 these groups, we observe that some of the characters 
 are constant and invariable ; that others are generally con- 
 stant ; that is, they are found in most of the groups ; 
 that others are constant in some groups, and generally 
 absent in others ; and that others have no constancy, but 
 vary in every order. Thus we have four kinds of cha- 
 racter, with reference to their constancy ; and it is in 
 direct ratio to its constancy that a character acquires
 
 RELATIVE VALUE OF CHARACTERS. 263 
 
 importance. To what organs should we, then, look for that 
 degree of constancy, which is of primary importance ? 
 
 (1.) Among the reproductive organs, the embryo is 
 the most important, for the development of this crgan is 
 the great object of vegetable life ; and the embryo, when 
 developed, is capable of perpetuating the species. But, 
 like every other organ, the embryo presents characters 
 of very unequal value. Of the first importance, obviously, 
 are its presence or absence ; its peculiar organization, 
 or mode of development, which is a necessary consequence 
 of this. The embryo furnishes two characters of the first 
 importance, viz.: 1. Plants with or without embryo ; 
 2. Plants with the cotyledonary extremity simple, or 
 divided. Those plants which have the cotyledonary 
 extremity simple, or, in other words, have a monocotyle- 
 donous embryo, have a coleorrhiza, and are called endo- 
 rrhizous; those with the cotyledouary extremity divided, 
 or, in other words, those which have a dicotyledonous 
 embryo, have a naked radicle, and are called exorrhizous. 
 
 (2.) The stamens also furnish characters of the first 
 importance. Their presence or absence needs not to be 
 mentioned, as it corresponds always with the presence 
 or absence of an embryo. The only constant character 
 of the first sort is the relative position of those organs 
 that is, their mode of insertion. (See pp. 101, 102.) 
 
 (3.) The nutritive organs also furnish characters of 
 the first importance. None of these organs are more 
 important than the vessels ; these are, however, absent 
 from some plants. Hence, two characters : cellular 
 plants, without vessels ; and vascular plants. Again, 
 the vessels are placed in the centre of the plant, increas- 
 ing its bulk to the inner part ; or they are placed ex- 
 teriorly, and the growth takes place outwardly. Hence, 
 vascular plants may be exogenous or endogenous. 
 
 361. Correspondence of Characters. The characters
 
 264 CHARACTERS OF LESS CONSTANCY. 
 
 stamped upon the organs essential to the two functions 
 of nutrition and reproduction, are equally important, as 
 is evident from the correspondence existing between them. 
 Thus, the divisions furnished hy the embryo correspond 
 exactly -with those furnished by the vessels: plants 
 without embryo are also without vessels ; those with 
 embryo have also vessels. Monocotyledons or Endorrhizse 
 are endogenous ; Dicotyledons or Exorrhizse are exogen- 
 ous. These are important coincidences. A certain 
 modification of one organ constantly involves a certain 
 modification of another : an inferior ovary, for instance, 
 invariably involves a monosepalous calyx ; a truly mono- 
 petalous corolla invariably involves the insertion of the 
 stamens into the corolla itself ; &c. 
 
 362. Characters of less Constancy. But we do not find 
 in all organs of plants characters so constant as those 
 furnished by the embryo and the vessels. 1. The second 
 sort consists of those which are generally constant through- 
 out a family, or with few exceptions. To this sort belong 
 the characters taken from the corolla, which may be 
 rnonopetalous, polypetalous, or none ; from the albumen, 
 which may be present or absent ; from the position of 
 the embryo relatively to the seed ; from that of the seed 
 relatively to the pericarp. 2. In the third sort, the 
 characters are constant in some families and entirely absent 
 in others. To this sort belong the number and proportion 
 of the stamens ; the combination of their filaments into 
 one, two, or several bundles ; the internal structure of 
 the fruit ; the number of its cells ; the mode of their 
 dehiscence ; the alternate or opposite position of the 
 leaves ; the presence of stipules, <fec. 3. To the fourth 
 sort, or those of no constancy at all, are referred the 
 various modes of inflorescence ; the forms of leaves, of 
 the stem ; the size of flowers, <fec. 
 
 363. Such are the principles on which plants are
 
 RECAPITULATION. 265 
 
 classified. All the organs are examined and compared, 
 their characters studied, and genera are grouped into 
 families accordingly. The characters of the first class 
 the structure of the embryo, the organization of the stem, 
 the insertion of the stamens, ought to be rigorously the 
 same in all genera of the same family. Those of the 
 second kind may sometimes fail. Those of the third kind 
 will generally be found combined in all the generic groups 
 of the same natural order, but they are not indispensable 
 in every case. 
 
 RECAPITULATION. 
 
 356. On what principle are plants grouped together in the 
 Natural System? What indications of such a system are 
 suggested by nature ? What are the advantages of the 
 Natural System ? 357. Distinguish between the terms indi- 
 vidual, species, and variety. Explain and illustrate the prin- 
 ciple by which genera and orders are established. What are 
 classes ? 358. What are the primary divisions adopted by 
 Jussieu, and on what characters are they founded ? Upon 
 what principle does his subdivision proceed ? 359. How did 
 De Candolle modify the classification of Jussieu ? State and 
 explain the terms adopted by De Candolle. 360. How many 
 kinds of character are determined in classifying plants ? On 
 what does their relative value depend ? Which is the most 
 important of the reproductive organs ? Why so ? What 
 characters are furnished by the embryo ? Distinguish between 
 exorrhizous and endorrhizous plants. What important cha- 
 racter is derived from the stamens? What characters are 
 derived from the nutritive organs ? 361. Point out the coin- 
 cidences of the characters derived from the nutritive and the 
 reproductive organs. 362. Enumerate the characters of the 
 second, of the third, and of the fourth sort. 363. Which of 
 these characters must be rigorously the same in all the genera 
 of a family ?

 
 GLOSSARY OF ADJECTIVE TEEMS. 
 
 [The Substantive Terms are fully explained in the body of the Work, 
 and may be found by reference to the Index.] 
 
 A. 
 
 Abruptly pinnate. When the petiole 
 of a pinnate leaf has no terminal leaflet 
 or tendril, as in orobus tuberosus. 
 
 Acaulescenl. Stemless ; applied to a 
 plant in which the stem is apparently 
 absent, aiid the leaves seem to rise from 
 the root, as in cnicus acaulis. 
 
 Accumbent. Lying against anything, 
 as the edges of the cotyledon against 
 the radicle in some cruciferous plants. 
 
 Acerose. Sharp-pointed, tapering to 
 a fine point, as the leaves of juniper. 
 
 Aciculate. Needle-shaped, as a crys- 
 tal; or marked with fine needle-like 
 streaks, as applied to surfaces. 
 
 Acinaciform. Scimitar-shaped ; plane 
 ou the sides, with one border thick, the 
 other thin, as the leaves of mesembry- 
 anthemum acinaciforme. 
 
 Aculeate. Prickly; applied to a sur- 
 face covered with prickles, as the stem 
 of rosa. 
 
 Acuminate. Pointed; tapering gra- 
 dually to a point, as the leaf of salix 
 alba. 
 
 Adnate. Grown to anything, as the 
 anther to the filament in polygonum. 
 
 Adventitious. Anything developed out 
 of the ordinary course, as aerial roots, 
 extra-axillary buds, &c. 
 
 Aggregate. Crowded together, as the 
 florets of the composite, the carpels of 
 ranunculus, &c. 
 
 Alternately pinnate. When the leaf- 
 lets of a pinnate leaf are placed alter- 
 nately on the common petiole, as in 
 potentilla rupestris. 
 
 Amphitropal. Anything curved round 
 the body to which it belongs, as the 
 embryo round the albumen, in the seed. 
 
 Amplexicaul. Stem-embracing, as ap- 
 plied to leaves which sheathe the stem. 
 
 Anatropous. Inverted; turned en- 
 tirely over, as applied to the ovule of 
 the apple. 
 
 Annulate. Ringed; surrounded by 
 rings, as certain vessels in plants, &c. 
 
 Antitropal. Anything which has a 
 direction contrary to that of the body 
 to which it belongs, as applied to the 
 direction of the embryo compared with 
 that of the seed. 
 
 Apetalous. Having no petals ; applied 
 to plants which have only one floral 
 envelope, as the laurel. 
 
 Apocarpous. When the carpels of a 
 flower are distinct from each other, as 
 distinguished from syncarpous, which 
 denotes their cohesion. 
 
 Appendiculate. That which has ap- 
 pendages, as applied to the calyx of 
 scutellaria, &c. 
 
 Arcuate. Bow-shaped ; bent like the 
 arc of a circle, as the legume of mendi- 
 cago falcata. 
 
 Areolate. Divided into areolee or small 
 spaces, as applied to surfaces. 
 
 Aspergilliform. Brush-like; divided 
 into minute ramifications, as the stig- 
 mas of grasses, certain hairs of the 
 cuticle, &c. 
 
 Atropous. That which is not invert- 
 ed, as applied to the ovule of the nettle, 
 and synonymous with orthotropous. 
 
 Attenuate. Tapering; gradually di- 
 minishing in breadth, and terminating 
 in a point. 
 
 Auriculate. Eared ; having two 
 rounded lobes at the base, as the leaf 
 of salvia officinalis. 
 
 Axillary, That which grows out of 
 an axil, as the leaf-bud of a plant.
 
 268 
 
 GLOSSARY OP ADJECTIVE TERMS. 
 
 B. 
 
 Baccate. Berried; having a juicy 
 consistence, as the fruit of ribes. 
 
 Barbate. Bearded; covered with 
 hairs resembling a beard, as applied to 
 surfaces. 
 
 Bicongregate. Bigeminate, or ar- 
 ranged in two pairs, as the leaflets of 
 mimosa unguis cati. 
 
 Bicrenate. Doubly crenate ; when the 
 crenate toothings of leaves are them- 
 selves creuate. 
 
 Bidentate. Two-toothed, as applied 
 to the fruit or aclienic of bidens. 
 
 Bifarious. Arranged in two rows, not 
 necessarily opposite to each other ; in 
 this particular, the term is differenced 
 from distichous. 
 
 Bifoliolate. When two folioles or 
 leaflets are developed at the same point 
 at the end of the petiole, as in zygophyl- 
 lum fabago. The term is synonymous 
 with conjugate. 
 
 Bifurcate. Twice-forked, as applied 
 to the inflorescence of stellaria, and sy- 
 nonymous with dtchotomous. 
 
 Bijuyous. In two pairs, as applied to 
 the leaflets of a pinnate leaf. 
 
 Bilobate. Two-lobed, as applied to 
 the leaves of Bauhinia, &c. 
 
 Binate. Growing in pairs; a term 
 synonymous with bifoliolate. 
 
 Bipartite. Parted in two, as applied 
 to the segments of a leaf. 
 
 Bipiuuate. When the leaflets of a 
 pinnate leaf themselves become pinnate, 
 as in fumana officinalis. 
 
 Hiserrate. Doubly-sawed, as applied 
 to the margins of leaves, when the ser- 
 rations are themselves serrate. 
 
 Biserial. Arranged in two series, or 
 rows; a term synonymous with bija- 
 rious. 
 
 Biternate. When three secondary 
 petioles proceed from the common pe- 
 tiole, and each bears three leaflets, as 
 in fumaria bulbosa. 
 
 Brachiate. Armed ; applied to bran- 
 ches which diverge nearly at right angles 
 from the stem. 
 
 C. 
 
 Caducous. Falling off early or readily, 
 as the calyx of poppy ; and opposed to 
 persistent, which denotes permanence. 
 
 Caspitose. Growing in tufts; form- 
 ing dense patches, or tufts, as the young 
 stems of many plants. 
 
 Calcarate. Having a calcar, or spur, 
 as the petals of aquilegia. 
 
 Calyculate. Having an involucrum 
 of bracts exterior to the calyx, as in 
 many composite. 
 
 Cali/ptrate. Having a calyptra or 
 hood, as the fructifying organ of mosses, 
 the calyx of eschscholtzia, &c. 
 
 Campanulate. Having the form of a 
 campanula or little bell, as applied to 
 the corolla. 
 
 Campylotropons. Bent upon itself, as 
 applied to the ovule of caryophyllaceous 
 plants, &c. 
 
 Canaliculate. Channelled ; long and 
 concave, as the leaves of tradescantia 
 virginica. 
 
 Cancellate. Latticed; applied to a leaf 
 which has veins without connecting pa- 
 renchyma, as in hydrogeton feuestralis. 
 
 Capitate. Headed; applied to hairs 
 which terminate in a glandular enlarge- 
 ment. 
 
 Carinate. Having a cariiia, or keel, 
 as the glumes of grasses, the two lowest 
 petals of a papilionaceous corolla. 
 
 Carnose. Of a fleshy consistence, as 
 applied to succulent leaves, &c. 
 
 Caudate. Tail -pointed; prolonged 
 into a long and weak tail-like point, as 
 certain petals, &c. 
 
 Cauline. Belonging to the caulis, or 
 stem, as applied to leaves. 
 
 Centrifugal. Leaving the centre ; 
 applied to inflorescences, in which the 
 central flowers open first. 
 
 Centripetal. Approaching the centre ; 
 applied to inflorescences in which, the 
 marginal flowers open first. 
 
 Cernuous. Drooping ; inclining from 
 the perpendicular towards the horizon; 
 applied to flowers. 
 
 Ciliated. Fringed with hairs, like an 
 eye-lash, as applied to the margin of 
 leaves. 
 
 Circinale. Rolled inwards from the 
 point to the base, like a lock of hair, as 
 the fronds of ferns. 
 
 Circuniscissile. Divided across by a 
 transverse separation, as the capsule of 
 hyoscyamus. 
 
 Cirrkose. Anything which terminates 
 in a tendril, or filiform appendage, as 
 the leaf of several leguminous plants. 
 
 Climate. Club-shaped ; thickest at the 
 upper end.as applied to filaments, styles, 
 the vittae of umbelliferous plants, &c. 
 
 Clypeate. Shield-shaped, as the scales 
 of the leaves of elseagnus, and synony- 
 mous with scutate, or scutil'onu.
 
 GLOSSARY OF ADJECTIVE TERMS. 
 
 269 
 
 Cochhate. Shell-shaped ; shortly spi- 
 ral, like a snail's shell, as the legume 
 of medicago cochleata, 8tc. 
 
 Comosc, Having como or hair at tlie 
 extremity, as the seed of asclepias. 
 
 Conduplicate. Doubled together: a 
 form of vernation or aestivation, in which 
 the sides of a leaf or petal are applied 
 parallelly to the faces of each other. 
 
 Confluent. Growing together ; the co- 
 hering of homogeneous parts ; synony- 
 mous with connate, cohering, &c. 
 
 Conjugate. Yoked together ; growing 
 in a pair, as the two leaflets of the pin- 
 nated leaf of zygophyllurn fahago. 
 
 Connate. Growing together, or co- 
 hering, as two opposite leaves ou the 
 stem. 
 
 Connivent. Converging ; having a 
 direction inwards, as the anther of so- 
 lanum tuberosum. 
 
 Contorted. Twisted in such a man- 
 ner that each piece of a whorl overlaps 
 its neighbour by one margin, and is 
 overlapped by its other neighbour by 
 the other margin, as in the aestivation 
 of oleander. 
 
 Convolute. Rolled together ; a form 
 of sestivation or vernation, in which 
 one petal or leaf is wholly rolled up in 
 another. 
 
 Cordate. Heart-shaped ; having two 
 rounded lobes at the base, as applied to 
 leaves. 
 
 Coriaceous. Of a leathery consistence, 
 as the leaves of primus laurocerasus. 
 
 Corneous. Of a horny consistence, 
 as the albumen of many plants. 
 
 Corniculate, Horned ; terminating 
 in a horn-like process, as the fruit of 
 trapa bicornis. 
 
 Corrugate. Wrinkled; folded up in 
 every direction, as in the aestivation of 
 poppy. 
 
 Corymbose. That arrangement of the 
 ramifications of plants, in which the 
 lower branches or pedicles are so long 
 as to bring the leaves or flowers to the 
 same level as that of the upper ones. 
 
 Crenate or crenelled. Having rounded 
 teeth ; applied to the edges of certain 
 leaves. 
 
 Crested. Having a helmet-like ridge, 
 as applied to seeds. 
 
 Cruciate or cruciform. Placed cross- 
 wise, as the floral envelopes of brassica. 
 
 CucuUate. Hooded; having the apex 
 and sides curved inward, as the upper 
 sep;il of aconitum. 
 
 Cuneateor cuneiform. Wedge-shaped; 
 
 inversely triangular, with rounded an- 
 gles, as applied to certain leaves. 
 
 Cuspidate. Spear-shaped ; tapering 
 to a stiff point; abruptly acuminate; 
 as applied to leaves. 
 
 Cyathiform. Cup-shaped ; as applied 
 to the form of some corollas. 
 
 Cymbiform. Boat-shaped, or navicu- 
 lar, as applied to the glumes of certain 
 grasses, and synonymous with carinate. 
 
 Cymose. Resembling a cyme, as ap- 
 plied to inflorescences and leafy bran- 
 ches. 
 
 D. 
 
 Deciduous. Falling off; synonymous 
 with caducous, and opposed to persis- 
 tent, which denotes permanence. 
 
 Dsclinate. Bent downwards ; applied 
 to the stamens, when they all bend to 
 one side, as in amaryllis. 
 
 Decumbent. Lying prostrate, but 
 rising from the earth at the upper ex- 
 tremity, as applied to the directions 
 taken by plants. 
 
 Decitrrent. Running down; applied 
 to leaves which are prolonged down the 
 stem, giving it a winged appearance. 
 
 Decussate. Crossing at right angles, 
 as pairs of leaves on the stem. 
 
 Dehiscent. That which opens spon- 
 taneously, as the thecse of anthers, cap- 
 sular fruits, &c. 
 
 Deliquescent. Melting away ; applied 
 to a panicle which is so much branched 
 that the primary axis disappears. 
 
 Deltoid. Shaped like I lie Greek letter 
 delta, as applied to certain leaves. 
 
 Dentate. Toothed ; having sharp teeth 
 with concave edges. 
 
 Depauperated. Starved; imperfectly 
 developed ; shrivelled, as from scanty 
 nutriment, as applied to certain stipules, 
 bracts, &c. 
 
 Depressed. Flattened from apex to 
 base, as applied to seeds; when flat- 
 tened lengthwise, they are said to be 
 compressed. 
 
 Diadelphous. Having the stamens 
 arranged in two distinct fasciculi. 
 
 Diandrous. Having two stamens, of 
 about the same length. 
 
 Diclwtomous. Having the ramifica- 
 tions always in pairs, or bifurcations, 
 as s tell aria. 
 
 Dicotyledonous. Having two cotyle- 
 dons or seed-lobes, as applied to the 
 embryo.
 
 270 
 
 GLOSSARY OF ADJECTIVE TERMS. 
 
 Didynamous. Having two pair3 of 
 stamens of unequal length. 
 
 Didymotis. Twins ; growing in pairs 
 as the fruit of galium. 
 
 Digitate, fingered; diverging from 
 a common centre ; as the lobes of the 
 leaf of horse-chestnut. 
 
 Dimidiate. Halved; half - formed ; 
 partially formed ; having one side only 
 perfect, as a leaf, an anther, &c. 
 
 Dioecious. Having stamens on one 
 plant, and pistils on another. 
 
 Dipterous. Two-winged ; as applied 
 to the two margins which are prolonged 
 on the surface of certain seeds. 
 
 Distichous. Arranged in two rows, 
 ;is the florets of many grasses, and sy- 
 nonymous with bifarious. 
 
 Divaricating. Spreading out nearly 
 at a right angle from anything, as 
 branches from a stem. 
 
 Dodecandrous. Having twelve sta- 
 mens, of about the same length. 
 
 Dolabriform. Hatchet - shaped ; as 
 applied to the leaves of a species of 
 mesembryanthemum. 
 
 Drupaceous. That kind of fruit which 
 has an indehiscent pericarp, fleshy ex- 
 ternally, bony internally, as the peach. 
 
 Dumose. The character of a shrub 
 which is low and much branched. 
 
 E. 
 
 Echinate. Bristly, covered with stiff 
 hairs or prickles, like an echinus ; as the 
 fruit of the sweet chestnut. 
 
 Emarginate. Having a notch at the 
 upper extremity, as if a portion had 
 been cut out of tlie margin, as the leaf 
 of box. 
 
 Endogenous. Inside - growing ; in- 
 creasing in diameter by depositions to 
 the centre. 
 
 Endorrhizous. That mode of germi- 
 nation in which the radicles are emitted 
 from within the substance of the radi- 
 cular end of the embryo, and are, in 
 fact, sheathed. 
 
 Enneandrous. Having nine stamens 
 of about equal length. 
 
 Ensiform. Sword-shaped ; straight, 
 flat, and pointed, as the leaf of iris. 
 
 Entire. Having no marginal division, 
 as applied to the leaves of galium. 
 
 Epigeous. Growing on the earth ; 
 applied to cotyledons which emerge 
 from the ground. 
 
 Epigynous. Inserted upon the sum- 
 
 mit of the ovarium, as applied to sta- 
 mens. 
 
 Equally pinnate. When the petiole 
 has no terminal leaflet or tendril; syno- 
 nymous with abruptly pinnate. 
 
 Eguitant. A form of vernation in 
 which the leaves overlap each other 
 parallelly and entirely, without involu- 
 tion, as in iris. 
 
 Erase. Gnawed ; having the margin 
 irregularly divided, as if bitten by some 
 animal ; applied to leaves. 
 
 Exogenous. Outside - growing ; in- 
 creasing in diameter by additions to 
 the exterior. 
 
 Exorrhizous. That mode of germi- 
 nation in which the radicle is not con- 
 tained within the substance of the em- 
 bryo, and consequently is not enclosed 
 in a sheath. 
 
 Extrorse. Turned outwards ; turned 
 away from the axis to which it belongs ; 
 applied to certain anthers. 
 
 F. 
 
 Falcate. Sickle-like; anything plane 
 and curved, with parallel edges, as the 
 legume of medicago falcata. 
 
 Farinaceous. Mealy; of (he nature 
 of flour ; as the albumen of wheat. 
 
 Fasciated. Banded; grown unnatu- 
 rally together, as contiguous stems, or 
 fruits. 
 
 Fasciculate. Clustered ; as when se- 
 veral bodies spring from a common 
 point, as the leaves of larix, the tubers 
 of orchis, the roots of commelina, &c. 
 
 Fastigiate. When the branches of a 
 tree are appressed to the stem, assum- 
 ing nearly the same direction, as in po- 
 pulus fastigiata. 
 
 Favose. Honeycombed ; excavated 
 like a honeycomb, as the receptacle of 
 onopordum, the seeds of poppy, &c. 
 
 Fenestrate. Windowed ; as applied 
 to the incomplete dissepiment some- 
 times occurring in the siliqua of cruci- 
 ferous plants. 
 
 Filiform. Thread-like ; as applied to 
 the filaments, and the styles, of plants. 
 
 Fimbriated. Fringed ; having the 
 margin bordered by filiform processes. 
 
 Fistulous. Cylindrical and hollow, as 
 the stems of grasses, of umbelliferous 
 plants, &c. 
 
 Flabelliform. Fan -shaped ; plaited 
 like the rays of a fan, as the leaves of 
 some palms.
 
 GLOSSARY OF ADJECTIVE TERMS. 
 
 271 
 
 Flagelliform. Whip-like ; long, taper, 
 and supple, as the stems or roots of 
 certain plants. 
 
 Flexuose. Wavy; bending alternately 
 inwards and outwards. 
 
 Floccose. Covered with tufts of wool- 
 liness, as the leaves of some species of 
 verbascum. 
 
 Fallacious. Leaf-like ; liaving the 
 form and texture of a leaf, as certain 
 floral envelopes. 
 
 Fugacious. Falling off, or perishing 
 rapidly, as the petals of cistus, minute 
 fungi, &c. 
 
 Fungi/arm. Having a rounded, con- 
 vex head, like that of a mushroom. 
 
 fusiform. Spindle-shaped ; thickest 
 in the middle, and tapering to both 
 ends, as the cells composing woody 
 fibre. 
 
 G. 
 
 Galeate. Arched like a helmet; as 
 applied to the upper lip of some labiate 
 corollas, as that of lamium album. 
 
 Gamopelalous. Having the petals 
 united; commonly termed monopeta- 
 lous. 
 
 Gamosepalmis. Having the sepals 
 united; commonly termed monosepa- 
 lous. 
 
 Geniculate. Knee-jointed; bent ab- 
 ruptly in the middle, as the stems of 
 some grasses. 
 
 Gibbous. That which has a convex 
 outline, as applied to solid bodies. 
 
 Glabrous. Smooth ; having a surface 
 free from hairs or any asperities. 
 
 Gladiate. Sword-shaped; a term of 
 the same signification as enslform. 
 
 Glandular. Covered with glanduli- 
 ferous hairs, as the leaves of sweet- 
 briar. 
 
 Glaucous. Azure-coloured ; covered 
 with bloom, like a plum. 
 
 Glumaceous. Having the floral enve- 
 lopes reduced to scales, called glumes, 
 as in grasses. 
 
 Grumous. Knotted, collected into 
 granular masses, as the fsecula of the 
 sago palm. 
 
 Gymnoipermons. Having the seeds 
 apparently naked, as distinguished from 
 angeiospermous, which denotes the pre- 
 sence of a seed-vessel. 
 
 Gynobasic. That state of the carpels, 
 in which they incline obliquely towards 
 the axis of the flower, as in rue. 
 
 Gyrate. Curved in, from apex to 
 base, as the fronds of ferns, and syno- 
 nymous with circinate. 
 
 H. 
 
 Hastate, Halberd-headed ; applied 
 to leaves which have three lance-shaped 
 lobes, one in the direction of the mid- 
 rib, the other two at the base at right 
 angles to the first, as in arum macula- 
 turn. 
 
 Ileptandrous. Having seven stamens, 
 of about equal length. 
 
 Herbaceous. Having the characters 
 of a herb, the tissue for the most part 
 green and cellular. 
 
 Heterotropal. That direction of the 
 embryo, in which it lies across the seed, 
 as in primrose. 
 
 Hexandrous. Having six stamens, of 
 about equal length. 
 
 Hirsute. Hairy; covered with long 
 and rather rigid hairs. 
 
 Hispid. Covered with long rigid 
 hairs, as the stem of echium vulgare. 
 
 Homotropal. Having the same direc- 
 tion as the body to which it belongs, 
 but not being straight; as applied to 
 the embryo of the seed. 
 
 Hypocrateriform. Salver-shaped; as 
 applied to a calyx or corolla, of which 
 the tube is long and slender, and the 
 limb flat, as in phlox. 
 
 Hypogeous. Subterranean ; as applied 
 to those cotyledons, which remain be- 
 neath the earth; and opposed to epi- 
 geous. 
 
 Hypogynous. Inserted beneath the 
 pistil, as applied to the stamens, the 
 corolla, &c. 
 
 I. 
 
 Icosandrous. Having twenty or more 
 stamens inserted into the calyx. > 
 
 Imbricated. A form of Aestivation, or 
 vernation, in which the pieces overlap 
 each other parallelly at the margins, 
 without any involution. 
 
 Impari-pinnate. Pinnate with an odd 
 one ; when the petiole of a pinnate leaf 
 is terminated by a single leaflet, as in 
 mountain-ash. 
 
 Incumbent. That which lies upon 
 anything, as when the cotyledons of 
 some cruciferous plants are folded with 
 tlieir backs upon the radicle. See Ac- 
 cumbent.
 
 272 
 
 GLOSSARY OF ADJECTIVE TERMS. 
 
 Indehiscent. Not opening spontane- 
 ously ; as applied to certain ripe fruits. 
 
 Induplicate. A form of vernation or 
 sestivation, in which the margins of the 
 leaves are bent abruptly inwards, and 
 the external face of these margins ap- 
 plied to each other, without any twisting. 
 
 Inermis. Unarmed ; as applied to 
 parts which have no spines or prickles. 
 
 Inferior. A term applied to the ova- 
 rium or fruit, when the calyx adheres 
 to its walls; when no such adhesion 
 occurs, the ovarium or fruit is termed 
 superior. So also the calyx is said to he 
 inferior in the latter case, superior in 
 the former. 
 
 Infundiltuliform. Funnel-shaped; ap- 
 plied to an organ with an obconical 
 tube, and an enlarged b'mb, as the co- 
 rolla of tobacco. 
 
 Innate. Growing upon anything by 
 one end, as when the anther is attached 
 by its base to the apex of the filament. 
 
 Intercellular. That which lies be- 
 tween the cells, or elementary tissues, 
 of plants. 
 
 Interrupted. A term denoting a die- 
 turbauce of a normal arrangement; a 
 leaf is said to be interruptedly pinnate, 
 when some of the pinnse are much 
 smaller than the rest, or absent. 
 
 Introrse. Turned inwards; as ap- 
 plied to anthers whose line of dehis- 
 cence is towards the axis of the flower, 
 and as opposed to extrorse. 
 
 Inrolute. A form of vernation or 
 Epstivation, in which the edges of the 
 leaves are rolled inwards spirally on 
 each side, as in the apple. 
 
 L. 
 
 Labiate. Lipped; divided into two 
 lips, as the corolla of lamium, the calyx 
 of prunella, &c. 
 
 Laciniate. Slashed; as a leaf divided 
 by deep, taper-pointed incisions. 
 
 Lacunose. Having large deep lacunae 
 or depressions on the surface. 
 
 Lanceolate. Lance-shaped; narrowly 
 elliptical, tapering to each end, as the 
 leaf of the mezereon. 
 
 Lenticular. Lens-shaped ; small, de- 
 pressed, and doubly convex, as the seed 
 of amaranth. 
 
 Lepidote. Leprous ; covered with 
 minute peltate scales, as the leaves of 
 elseaguua. 
 
 Ligneous. Woody; having the struc- 
 tures and other characters of wood. 
 
 Ligulate. Strap - shaped ; narrow, 
 somewhat long, with the two opposite 
 margins parallel, as the florets of tarax- 
 acum. 
 
 Linear. Narrow, with the two oppo- 
 site margins parallel, as the leaf of a 
 pine. 
 
 Locitlicidal. That mode of dehiscence 
 of fruits, in which the loculi, or cells, 
 are severed at their back. 
 
 Lunate. Crescentiform, or semilunar ; 
 having the form of a crescent. 
 
 Lyrate. Lyre-shaped ; applied to a 
 leaf which has several sinuses on each 
 side, gradually diminishing in size from 
 above downwards, as in charlock. 
 
 M. 
 
 Marcescent. Withering or fading, 
 some time before it falls off, as the 
 flowers of orobanche. 
 
 Medullary. A term applied to radii 
 proceeding from the medulla to the 
 bark, in exogenous stems. 
 
 Monadelphous. In one adelphia, or 
 combination, as the stamens of malva. 
 
 Monandroui. Having only one sta- 
 men : the first class in Linnieu's's system. 
 
 Moniliform. Necklace-like; cylindri- 
 cal, and contracted at regular intervals, 
 as the lomentum of ornithopns." 
 
 ilonocotyledonous. Having only one 
 cotyledon, or seed-lobe, as a palm. 
 
 Monopetalous. Having a single petal ; 
 or, more correctly, consisting of seve- 
 ral cohering petals, and therefore better 
 expressed by the term gamopetaloui. 
 
 Monosepalous. Having a single sepal ; 
 or, more correctly, consisting of several 
 cohering sepals, and therefore better 
 expressed by the term gamoiepalous. 
 
 Atticronate. Abruptly terminated by 
 a hard short point ; applied to leaves. 
 
 Multifid. Cut into many parts ; ap- 
 plied to leaves which have numerous 
 shallow segments. 
 
 Multipartite. Divided into many 
 parts ; applied to leaves which have 
 many deep lobes. 
 
 Miiricated. Covered with numerous 
 short hard prominences, as the pericarp 
 of ranunculus aryensis. 
 
 Muriform. Wall-like; applied to the 
 tissues constituting tlie medullary rays, 
 from its presenting an appearance simi- 
 lar to that of bricks in a wall.
 
 GLOSSARY OF ADJECTIVE TERMS. 
 
 273 
 
 N. 
 
 Napiform. Turnip-shaped ; having 
 the figure of a depressed sphere. 
 
 Naricular. Boat-shaped ; concave, 
 tapering to both ends, with a keel ex- 
 ternally, as the glumes of some grasses. 
 
 Nutans. Nodding; inclining from 
 the perpendicular, with the upper ex- 
 tremity pointing downward, aa the 
 flower of galanthus. 
 
 0. 
 
 Obvolute. A form of vernation or 
 aestivation, in which the margins of one 
 leaf alternately overlap those of the 
 leaf which is opposite to it. 
 
 Octandrous. Having eight stamens 
 of nearly equal length. 
 
 Operculate. Having an opercnlum or 
 lid, as the theca of mosses, the calyx of 
 eucalyptus, &c. 
 
 Orbicular. Completely circular, as 
 tiie leaf of cotyledon orbiculare. 
 
 OrtAotropal, Straight, aud having 
 the same direction as the body to which 
 it belongs ; as applied to the embryo of 
 the seed. 
 
 Orthotropous. Erect ; applied to the 
 ovule, when it is rectilinear, and its 
 base is in contact with the hilum. 
 
 Oscillating. Versatile; swingingback- 
 wards and forwards, from being nicely 
 balanced by its middle; as applied to 
 some anthers. 
 
 Ovate. Egg-shaped ; oblong or ellip- 
 tical, and broadest at the lower end; as 
 applied to leaves. 
 
 P. 
 
 Paleaceous. Chaffy; covered with 
 palese, or membranous scales, as the 
 receptacle of some compositse. 
 
 Palmate. A form of leaf, haying five 
 lobes, with the midribs radiating from 
 a common point at the base of the leaf, 
 and resembling the palm of the hand. 
 
 Palmatifid, A variety of the palmate 
 leaf, in which the lobes are divided as 
 far down as half the breadth of the 
 leaf. 
 
 Palmatipartite. A variety of the 
 palmate leaf, in which the lobes are di- 
 vided beyond the middle, and the pa- 
 renchyma is not interrupted. 
 
 Palmatisecled. A variety of the pal- 
 mate leaf, in which the lobes are di- 
 
 vided down to the midrib, and the pa- 
 renchyma is interrupted. 
 
 Palmatilobate. A variety of the pal- 
 mate leaf, in which the lobes are di- 
 vided to an uncertain depth. 
 
 Panduriform. Fiddle-shaped ; obo- 
 vate, with a deep sinus on each side, as 
 the leaves of rumex pulcher. 
 
 Papilionaceous. Butterfly-shaped ; 
 a form of corolla characteristic of the 
 leguminous plants of Europe. 
 
 Parietal. Belonging to or developed 
 from the parietes or walls of an organ. 
 Pari-finnate. Equally pinnate, ab- 
 ruptly pinnate; when the petiole of a 
 pinnate leaf is terminated by neither a 
 leaflet nor a tendril. 
 
 Partite. Parted or divided into a 
 fixed number of segments, which are 
 divided nearly down to the base, as ap- 
 plied to leaves: a leaf with two divi- 
 sions is called bipartite ; with three, tri- 
 partite ; with many, pluripartite, &c. 
 
 Pectinate. A modification of the 
 pinnatifid leaf, in which the segments 
 are long, close, and narrow, like the 
 teeth of a comb. 
 
 Pedate. A modification of the pal- 
 mate leaf, in which the two lateral lobes 
 are themselves subdivided, as in holle- 
 borus niger. The same modifications 
 occur as in the palmate leaf, with simi- 
 lar terms, as pedatifid, pedatipartite, 
 pedatisected, and pedatilobate. 
 
 Peltate. Shield-shaped; applied to 
 leaves which are fixed to the petiole by 
 their centre, or by some point within 
 the margin, as in tropseolum. 
 
 PcntanJrous. Having five stamens, 
 of about equal length. 
 
 Perennial. Lasting for several years, 
 as differenced from annual and biennial. 
 
 Perfoliate. A designation of a leaf, 
 which, by union of its margins, incloses 
 the stem, which thus seems to pass 
 through it. 
 
 Perigynous. Growing from the sides 
 of the calyx, and thus surrounding the 
 ovarium, as applied to the stamens. 
 
 Peritropal. Directed from the axis 
 to the horizon, as applied to the embryo 
 of the seed. 
 
 Persistent. Not falling off, but re- 
 maining green for a long time, as the 
 calyx of labiate plants, what are called 
 evergreen leaves, &c. 
 
 Personate. Masked; a form of the 
 gamopetalous corolla, resembling a 
 mask with an open mouth. 
 
 Pelalaid. Resembling a petal} as 
 8
 
 274 
 
 GLOSSARY OF ADJECTIVE TERMS. 
 
 pome of the filaments of uymphsea, the 
 stigmas of iris. &c. 
 
 Pilose. Covered with long, soft, and 
 erect hairs, as applied to surfaces; or 
 consisting of hair-like processes, as the 
 limb of the calyx in composite plants. 
 
 Pinnate. Tfiat form of leaf in which 
 simple leaflets are placed on each aide 
 of a common petiole, as in polypody. 
 The same modifications occur as "in tlie 
 I Ornate leaf, with similar terms, as pin- 
 natifid, pinnatipartite, pinnatisected, 
 ind pinnatilobate. 
 
 Plaited, A form of aestivation or 
 vernation, in which the leaves are 
 folded lengthwise, like the plaits of a 
 fan, as in many palms. 
 
 Polyadelphous. Arranged in several 
 fasciculi, as applied to stamens. 
 
 Polyandrous. Having an indefinite 
 number of stamens, inserted beneath 
 the pistil. 
 
 Polypetalovs. Having several petals, 
 distinct from each other. 
 
 Polyitpalous. Having several sepals, 
 distinct from each other. 
 
 Preemorse. Abruptly bitten off: the 
 appearance presented by the main root 
 of scabiosa succisa. 
 
 Pubescent. Covered with down or 
 pubescence, consisting of short, soft 
 hairs, as applied to surfaces. 
 
 Pyriform. Pear-shaped ; inversely 
 conical. 
 
 Q. 
 
 Quincunx. A form of aestivation or 
 vernation, in which there are five leaves, 
 two of which are exterior, two interior, 
 and the fifth covers the interior with 
 one margin, while its other margin is 
 covered by the exterior, as in rose. 
 
 R. 
 
 Radical. Arising from the radix, or 
 root as applied to the leaves of what 
 are called acaulescent plants. 
 
 Ramentaceous. Covered with ramenta, 
 or brown shrivelled scales, as the stems 
 of many ferns. 
 
 Ramose. Branched ; having many 
 ramifications ; when only somewhat 
 branched, the term tubramose is used. 
 
 Reniform. Kidney-shaped; crescent- 
 shaped, with the ends rounded ; applied 
 to leaves and seeds. 
 
 Replicate. A form of vernation or 
 
 aestivation, in which the upp 
 
 the leaf is curved back and app'lied to 
 
 the lower, as in aconite. 
 
 Reticulate. Netted; as applied to the 
 vernation of the leaves of exogenous 
 plants. 
 
 Revolute. A form of vernation or 
 aestivation, in which the edges of the 
 leaf are rolled backwards spirally on 
 each side, as in rosemary. 
 
 Ringent. A term synonymous with 
 personate, and indicative of the gaping 
 appearance of the corolla. 
 
 liostrate. Beaked ; terminating in a 
 long, hard process, as the siliqua of 
 sinapis. 
 
 Rosulate. Having the leaves or other 
 parts arranged in clusters, like the pe- 
 tals of a double rose, owing to contrac- 
 tion of the internodea of the stem. 
 
 Rotate. Wheel-shaped ; applied to a 
 calyx or coralla, of which the tube is 
 very short, and the segment? spread- 
 ing, like the radii of a wheel, as in 
 borago. 
 
 Ruminated. A term applied to the 
 albumen in certain cases, in which it is 
 perforated in various directions by dry 
 cellular tissue, as in nutmeg. 
 
 Runcinate. Hook-backed ; having its 
 segments pointing downwards, like the 
 teeth of a saw, as the leaf of taraxacum. 
 
 Rupturing. A mode of dehiscence, 
 in which the pericarp is spontaneously 
 perforated by holes, as in antirrhinum. 
 
 s. 
 
 Sagittate. Arrow-headed ; applied to 
 leaves which are pointed at the apex, 
 and gradually enlarge at the base into 
 two acute lobes, as in sagittaria. 
 
 Scabrous. Rough ; covered with hard 
 short projections from the cuticle, as 
 the leaves of symphytum. 
 
 Scarious. Dry, thin, and shrivelled, 
 as the bracts of the involucruui of cen- 
 taurea. 
 
 Scrobiculate. Having numerous small 
 irregular pits or depressions, as certain 
 seeds. 
 
 Scutiform or scutate. Buckler-shaped; 
 as the scales constituting the scurliuess 
 of the leaves of elssagnus. 
 
 Semi-amplexicaul. Half stem-embrac- 
 ing; applied to leaves which partially 
 sheath the stem. 
 
 Semi-anatropoui. A term denoting 
 the same as ampkilropout, except that
 
 GLOSSARY OP ADJECTIVE TERMS. 
 
 275 
 
 in the former the ovule is parallel with 
 the funiculus, while iu the latter it is at 
 right angles with it. 
 
 Septicidal. That kind of dehiscence 
 in which the septa of a compound fruit 
 separate each into two laminse. 
 
 Septifragal. That kind of dehiscence 
 in which the backs of the carpels sepa- 
 rate from the septa, which adhere to 
 the axis. 
 
 Sericeous. Silky ; covered with long, 
 fine, appressed hairs, giving the surface 
 a silky appearance. 
 
 Serrate. Sawed ; having the edge 
 divided into sharp straight-edged teeth, 
 pointing upwards like a saw. When 
 the serrations are themselves serrate, 
 the margin of the leaf is termed biserratc. 
 
 Sessile. That which is seated upon 
 anything ; a leaf is sessile on the stem 
 when it has no petiole; an anther is 
 sessile which has no filament, &c. 
 
 Setose. Bristly ; covered with short, 
 stiff hairs, as the leaves of bugloss, the 
 pappus of some composite plants, &c. 
 
 Sinuate. Having a wavy margin, ir- 
 resrularly convex and concave. 
 
 Spadicose. Having the organs of re- 
 production arranged upon a spadix, as 
 arum. 
 
 Spathaceous. Having the organs of 
 reproduction inclosed within a spathe, 
 or large sheathing bract, as arum. 
 
 Spatulate. Like a spatula; oblong, 
 with the lower end much contracted, 
 as the leaf of daisy. 
 
 Squarrose. Consisting of parts which 
 spread out at right angles from a com- 
 mon centre ; applied to leaves, &c. 
 
 Stellate. Star-like; applied to the 
 leaves of galium, the hairs of most mal- 
 vaceous plants, &c, 
 
 Stipitate. Stalked ; that which is 
 furnished with a stalk, as the pappus of 
 some composite plants. The terra does 
 not apply to the petiole of a leaf, or the 
 peduncle of a flower. 
 
 Stipulate. Furnished with stipules, 
 exstipulate, having no stipules. 
 
 Striffose. A terra applied to a surface 
 which is covered with stiff hairs. 
 
 Stropkiolate. A term applied to the 
 umbilicus of seeds, when they are sur- 
 rounded by irregular protuberances, 
 called strophiolse or carunculae. 
 
 Stupose. Having a tuft of hairs at 
 some part, as certain filaments, &c. 
 
 Subulate. Awl-shaped ; linear, taper- 
 ing to a line point, as the leaves of ulex. 
 
 Succulent. Very cellular and juicy, 
 
 as the stem of cactus, the leaf of sem- 
 pervivum, &c. 
 
 Superior. A term applied to the fruit 
 when it has no cohesion with the calyx, 
 the latter being then termed inferior. 
 Contrariwise, a cohering calyx is termed 
 superior, the invested fruit being then 
 termed inferior. 
 
 Sutural. A mode of dehiscence, in 
 which the suture of a follicle or legume 
 separates spontaneously. 
 
 Synantherous. Growing together by 
 the anthers ; the characteristic feature 
 of the compositae, and a more expres- 
 sive term than the more common one, 
 syngcnesiotu. 
 
 Syncarpotts. A term applied to a 
 compound fruit, in which the carpel* 
 are grown together, as in poppy. 
 
 Syngenesiotts. Growing together, as 
 applied to the anthers of composites. 
 Synantherous is a better term. 
 
 T. 
 
 Terete. Taper ; as applied to stems, 
 and distinguished from angular. 
 
 Ternate. A term applied to parts 
 which are united in three leaves, as 
 leaves, &c. 
 
 Tetru.dyna.mous. Having six stamens, 
 of which two pairs are longer than the 
 third pair. 
 
 Tetrandrotu. Having four stamens, 
 of about equal length. 
 
 Tomentose. Covered with tomentum, 
 or short close down. 
 
 Torulose. Knotted ; irregularly con- 
 tracted and distended, as applied to 
 cylindrical bodies, or seed-vessels. 
 
 Trapcziform. Four -sided, with the 
 opposite margins not parallel, as certain 
 leaves. 
 
 Triadelphous. Having the stamens 
 disposed in three parcels or fasciculi. 
 
 Triandroui. Having three stamens 
 of about equal length. 
 
 Trichotomous. Having the divisions 
 or ramifications always in threes, as 
 mirabilis jalapa. 
 
 Tripinnate. A term applied to a leaf 
 iu which there are three series of pin- 
 nation ; viz., when the leaflets of a bi- 
 pinnate leaf are themselves pinnate, as 
 in tlialictrum minus. 
 
 TrUcrnate. A term applied to a leaf 
 in which there are three series of ter- 
 nation ; viz., when the leaflets of a biter- 
 nate leaf are themselves ternate.
 
 276 
 
 GLOSSARY OF ADJECTIVE TERMS. 
 
 Truncate. Terminating very abrupt- 
 ly, as if a portion had been cut off, as 
 the leaf of tulip-tree. 
 
 Turbinate. Top - shaped ; inversely 
 conical, and contracted towards the 
 point. 
 
 u. 
 
 Unguiculate. Clawed; a terra ap- 
 plied to a petal furnished with an un- 
 guis or claw, as in pink. 
 
 Urceolate. Pitcher-shaped; as ap- 
 plied to the envelope formed by the two 
 confluent bracts of carex, to certain 
 corollas, &c. 
 
 V. 
 
 Vascular. The name of a tissue, con- 
 sisting of spiral vessels and their modi- 
 fications, or ducts. 
 
 Ventral. A term applied to that 
 suture of the legume to which the 
 
 seeds are attached; the opposite suture 
 is the dorsal. 
 
 Ventricose. Bellying ; inflated in 
 some parts, as applied to certain corol- 
 las, &c. 
 
 Verrucose. "Warty ; covered with 
 little excrescences or warts. 
 
 Versatile. Swinging backwards and 
 forwards, as applied to anthers, and 
 synonymous with oscillating, 
 
 Verticillate. "Whorled; a term de- 
 noting that arrangement of leaves in 
 which three or more are placed opposite 
 to each other in the same plane. 
 
 Villous. Covered with long, soft, 
 shaggy hair, as epilobium hirsutum. 
 
 Voluble. Twisting; as applied to 
 stems which twist round other bodies, 
 the hop to the right, the bindweed to 
 the left. 
 
 W. 
 
 Whorled. A term synonymous with 
 verticillate.
 
 INDEX. 
 
 Abortion of organs, 112. 
 
 Branches, direction of, 34. 
 
 Absorption, 157. 
 
 Calyx, 85. 
 
 Achenium, 121. 
 
 monosepalous, 86. 
 
 Acids, 174. 
 
 polysepalous, 86. 
 
 Acorn, 122. 
 
 Cambium, 170. 
 
 Acotyledons, 21, 136. 
 
 Camphor, 174. 
 
 Acrogenous growth, 136. 
 
 Canker, 202. 
 
 Adventitious substances, 175. 
 
 Caoutchouc, 174. 
 
 .Estivation, 82. 
 
 Capitulum, 72. 
 
 Aggregate fruits, 123. 
 
 Capsule, 122. 
 
 Air, its action, 151. 
 
 Carcerulus, 121. 
 
 Albumen, 127. 
 
 Carcinoma, 234. 
 
 Alburnum, 37, 41. 
 
 Carpels, 104. 
 
 Algae, 136. 
 
 Catkin, 72. 
 
 Alkalies, 174. 
 
 Caudex, 23. 
 
 Amphisarca, 123. 
 
 Caryopsis, 121. 
 
 Analogies of plants and animals, 3. 
 
 Cellulares, 22. 
 
 Anther, 98. 
 
 Cellular tissue, 7. 
 
 attachment of, 99. 
 
 Centrifugal growth, 137. 
 
 direction of, 99. 
 
 Chalaza, 127. 
 
 form of, 99. 
 
 Characese, 135. 
 
 Anthodium, 72. 
 
 Classification of plants, 20. 
 
 Anthophore, 69. 
 
 Claw, 89. 
 
 Apple, 122. 
 Ascent of the sap, 160. 
 
 Colour of plants, 166. 
 Compound fruits, 121. 
 
 Assimilation, 178. 
 
 Conceptaculum, 124. 
 
 Atmosphere, actiou of fruits on, 203. 
 effects of respiration on, 
 
 Cone, 123. 
 Conservative organs, 5. 
 
 167. 
 
 Cormus, 29. 
 
 
 Corolla, 89. 
 
 Bacca, 122. 
 
 duration of, 95. 
 
 Balauata, 124. 
 
 monopetalous, 90. 
 
 Balsams, 174. 
 
 polypetalous, 92. 
 
 Bark, 37, 39. 
 
 regular and irregular, 
 
 Berry, 122. 
 
 Corymb, 72. 
 
 Blanching, 233. 
 Botanical Geography, 221. 
 Botany, divisions of, 4. 
 
 Cotyledons, 128. 
 Creeping stem, 30. 
 Cremocarpium, 124. 
 
 Buds, 45, 81. 
 
 Cryptogamic plants, 132. 
 
 their arrangement, 46. 
 
 Cryptogamous plants, 22. 
 
 composition, 46. 
 
 Culm, 32. 
 
 subterranean, 47. 
 
 Cupule, 69. 
 
 Bulb, 48. 
 
 Cuticle, 14. 
 
 Bulbils, 48. 
 
 Cyclosis, 171. 
 
 Bractea, 68. 
 
 Cyme, 73, 74. 
 
 modifications of, 68. 
 
 Cynorrhodon, 120. 
 
 of grasses, 69. 
 
 
 Branches, 33. 
 
 Decarbonization, 140. 
 
 development of, 47. 
 
 Decay of plants, 237.
 
 278 
 
 INDEX. 
 
 Decomposition of plauts, 238. 
 Debiscence of anther, 100. 
 
 fruit, 118. 
 
 Descending sap, 170. 
 Dicotyledons, characters of, 520. 
 Diplotegia, 124. 
 Direction of the organs, 210. 
 Diseases of plants, 233. 
 Disk, 111. 
 Dissemination, 205. 
 Drupe, 120. 
 Ducts, 11, 12. 
 Duramen, 37, 41. 
 Duration of plants, 235. 
 
 Fruits, aggregate, 123, 
 
 compound, 121. 
 
 simple, 120. 
 Fungi, 136. 
 
 Gangrene, 233. 
 
 Geographical distribution, 221. 
 
 Germination, 139. 
 
 in dicotyledons, 112. 
 
 in monocotyledons, 14-2. 
 
 its conditions, 139. 
 Germ-vesicle, 199. 
 Glands, 17. 
 Gourd, 122. 
 Grafting, 180. 
 
 Electricity, its action, 154. 
 
 Gravitation, its effects, 211. 
 
 Elementary organs, 5. 
 
 Growth of plants, 145. 
 
 Embryo, 127. 
 
 stems, 181, 182. 
 
 dicotyledonous, 129. 
 
 Gum, 172. 
 
 monocotyledonous, 130. 
 
 
 Endocarp, 117. 
 
 Habitations of plauts, 224. 
 
 Endogenous, 21. 
 
 Hairs, 15. 
 
 Endopbloeum, 41. 
 
 Heat, its action, 153. 
 
 Endosmose, 151. 
 
 Hepaticse, 135. 
 
 Epicarp, 116. 
 
 Hesperidium, 122. 
 
 Epidermis, 14, 87. 
 
 Hilum, 127. 
 
 Epiphlceum, 40. 
 
 Horary expansion of flowers, 
 
 Equisetacese, 133. 
 
 Hybrids, 230. 
 
 Ergot, 234. 
 
 
 Etterio, 121. 
 
 Inflorescence, 66, 70. 
 
 Excrescences, 234, 
 
 lusertion of stamens, 101. 
 
 Excretions, 176. 
 
 Integuments, general, 14. 
 
 Exhalation, 164. 
 
 Intercellular passages, 8, 12. 
 
 Exogenous, 21, 
 
 luvolucrum, 68, 73. 
 
 
 Irritability, 148 
 
 Fascicle, 73. 
 
 
 Fecula, 172. 
 
 Kernel, 127. 
 
 Fecundation, 193, 197. 
 
 
 Fermentation, 238. 
 
 Lacunae, 12. 
 
 Ferns, 132. 
 
 Lamina, 90. 
 
 Fibre, 7, 9. 
 
 Leaf, its nature, 49. 
 
 Fig, 123. 
 
 fall of the, 236. 
 
 Filament, 98. 
 
 Leaves, 49. 
 
 Fixed oils, 173. 
 
 colour of, 61. 
 
 Floration, 189. 
 
 compound, 55, 57. 
 
 Flower, 79. 
 
 direction of, 52, 213. 
 
 to parts, 80, 83. 
 
 disposition of, 50. 
 
 buds, 81. 
 
 duration of, 61. 
 
 horary expansion of, 192. 
 Flowering, mode of, 6fi. 
 
 expansion of, 59. 
 insertion of, 52. 
 
 periodicity of, 191. 
 Flowerless plants, reproduction of, 208. 
 
 in nation of, 55. 
 simple, 55. 
 
 structure of, 132. 
 
 figure of, 56. 
 
 Follicle, 120. 
 
 their situation, 50. 
 
 Food of plants, 158. 
 
 surface of, 61. 
 
 Fruit, 116. 
 
 Legume, 120. 
 
 chemical changes in, 204. 
 
 Liber, 37, 39. 
 
 maturation of, 200. 
 
 Lichens, 135. 
 
 iits progress, 203. 
 varieties of, 119. 
 
 Life of plants, 147. 
 Light, its action, 152, 212.
 
 INDEX. 
 
 279 
 
 Lignin, 173. 
 
 Limb of the leaf, 54. 
 
 petal, 90. 
 
 Linnrean System, 243. 
 Longevity of trees, 235. 
 Lycopodiacese, 133. 
 Lymph, 160. 
 
 Marsileacese, 133. 
 Maturation, 200. 
 Medullary sheath, 37, 42. 
 
 rays, 37, 42. 
 Membrane, 7- 
 Mesocarp, 117. 
 Mesophloeum, 40. 
 Metamorphosis of organs, 215. 
 irregular, 218. 
 Meyen's views, 198. 
 Migrations of plants, 225. 
 Monocotyledonous embryo, 130. 
 Monocotyledons, character of, 21. 
 Moisture, influence of, 207. 
 Morphology, 218. 
 Mosses, 134. 
 Motility, apparent, 3. 
 Movements caused by touch, 149. 
 spontaneous, 150. 
 peculiar or local, 171. 
 
 Natural System, 259. 
 Nectaries, 111. 
 Nervation, 55. 
 Nucula, 120. 
 Nucleus, 127. 
 Nuculanium, 124. 
 Nutrition, 156. 
 Nutritive organs, 5, 18. 
 
 Odour of plants, 177. 
 Oils, 173. 
 
 Omphalodium, 127. 
 Organs of plants, 5, 18. 
 
 elementary, 5, 18. 
 
 nutritive, 5, 18. 
 
 perfected, 19. 
 
 reproductive, 18. 
 
 rudimentary, 19. 
 Ovary, 104. 
 
 its dissepiments, 105. 
 
 form, 105. 
 Ovules, 106. 
 
 development of, 200. 
 
 Panicle, 73. 
 Pappus, 87. 
 Parenchyma, 49. 
 Peduncle, 66. 
 
 its position, 67. 
 Pepo, 122. ' 
 Periodicity of flowering, 191. 
 
 Perfected organs, 19. 
 Perianth, 85. 
 
 its functions, 192. 
 Pericarp, 116. 
 
 its structure, 117. 
 its progress, 203. 
 Perisperm, 126. 
 Petals, 89. 
 
 position of, 94. 
 Petiole, 52, 54. 
 Phanerogamous plants, 22. 
 Physiology, vegetable, 139. 
 Pistil, 103. 
 Pitcher, 63. 
 Pith, 42. 
 
 Plants aud animals, their analogies, 3. 
 their distinctions, 2. 
 their principal cha- 
 racters, 2. 
 Plants, their functions, 139. 
 
 general idea of, 1. 
 
 classification of, 20. 
 Plumule, 128. 
 Poisons, action of, 151. 
 Pollen, 100. 
 
 its development, 101. 
 dispersion, 101, 196. 
 
 formation of, 195. 
 
 protection of, 195. 
 Pomum, 122. 
 
 Preservation of seeds and fruits, 207. 
 Prickles, IB, 35. 
 Propagation, 187, 188. 
 Proper vessels, 13. 
 Pruning, 179. 
 Pubescence, 16, 35. 
 Putrefaction, 220. 
 
 Raceme, 71, 76. 
 Radicle, 127. 
 Raphe", 127. 
 Receptacle, 69, 110. 
 
 of the flower, 80, 81. 
 Receptacles of juices, 13. 
 Reproduction, 187, 189. 
 Reproductive organs, 6. 
 Resins, 174. 
 Respiration, 165. 
 Rhizoma, 30. 
 Root, 23. 
 
 direction of the, 28. 
 
 duration of, 24. 
 
 position of, 24. 
 
 principal kinds of, 25. 
 
 structure, 23, 43. 
 Rootstock, 80. 
 Rudimentary organ, 19. 
 Runner, 32. 
 
 Samara, 121.
 
 280 
 
 INDEX. 
 
 Sap, 160. 
 
 ascent of, 160. 
 channels of, 162. 
 elaborated, 169. 
 its descent, 170. 
 Scales, 17. 
 Scape, 67. 
 
 Schleiden's views, 198. 
 Secretions, 172. 
 Seed, 126, 
 
 its progress, 202. 
 mature, composition of, 205. 
 Sepals, 86, 
 Sertule, 72. 
 Sexes, 194. 
 Silicula, 122. 
 Siliqua, 121. 
 Simple fruits, 120. 
 Sleep of plants, 149. 
 Smut, 234. 
 
 Soil, influence of, 226. 
 Sorosis, 123. 
 Spadix, 72. 
 Spatha, 69. 
 
 Species, general idea of, 209. 
 Spermoderm, 126. 
 Spike, 71, 75. 
 Spikelet, 71. 
 Spines, 35, 63. 
 Spiral vessels, 11. 
 Spongioles, 24. 
 Spores, or sporules, 132. 
 Stamens, 96. 
 
 insertion of, 101. 
 their number, 97. 
 position and direction, 97. 
 Starch, 172. 
 Stations of plants, 222. 
 Stem, 29, SI. 
 
 consistence of, 32. 
 of dicotyledons, 36. 
 of monocotyledons, 43. 
 structure of, 35. 
 varieties of, 29. 
 Stigma, 107. 
 
 its action, 197. 
 Stings, 16. 
 Stipules, 62. 
 
 Stimulants to vegetation, 152. 
 
 Stipe, 31. 
 
 Homata, 15. 
 
 Structure of plants, 6. 
 
 Style, 107. 
 
 Subdivision, propagation by, 188. 
 
 Sucker, 32. 
 
 Sugar, 172. 
 
 Syconus, 123. 
 
 Taste of plants, 177- 
 Tendrils, 62. 
 Testa, 126. 
 Thorns, 36. 
 Thyrsus, 73, 77. 
 Tissue, cellular, 7. 
 
 elementary, 5. 
 
 vascular, 10. 
 
 woody 9. 
 
 properties of, 147. 
 Torus, 80. 
 Trachea, 11. 
 Transpiration, 164. 
 Trunk, 31. 
 Tuber, SO. 
 
 Umbel, 73. 
 Umbilicus, 127. 
 Utricle, 123. 
 
 Vacuities in tissue, 12. 
 Varieties, 230. 
 Vascular tissue, 10. 
 Vegetable life, 147. 
 Vegetables, general idea of, 1. 
 Vernation, 63. ^ 
 Vessels, spiral," 11. 
 proper, 13. 
 Volatile oils, 173. 
 
 Warts, 17. 
 
 Water, its action, 154. 
 
 Wax, 173. 
 
 Whorl, 70. 
 
 Woody layers, 37. 
 
 tissue, 9. 
 
 fibre, 9.
 
 7 000047868 5 
 
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