LANiJSCAKt ARCHITECTURE Ex Libris BEATRIX JONES REEF POINT GARDENS LIBRARY The Gift of Beatrix Farrand to the General Library University of Calif ornia,Berkeley GRAY'S BOTANICAL TEXT-BOOK. f* VOLUME I. STRUCTURAL BOTANY. GRAY'S BOTANICAL TEXT-BOOK CONSISTS OF VOL. I. STRUCTURAL BOTANY. By ASA GRAY. II. PHYSIOLOGICAL BOTANY. By GEORGE L. GOODALE. III. INTRODUCTION TO CRYPTOGAMIC BOTANY, BOTH STRUCTURAL AND SYSTEMATIC. By WILLIAM G. FARLOW. {In preparation.) IV. SKETCH OF THE NATURAL ORDERS OF PH^ENOGAMOUS PLANTS; their Special Morphology, Useful Pro- ducts, &c. {In preparation.) GRAY'S BOTANICAL TEXT-BOOK. (SIXTH EDITION.) VOL. I. STRUCTURAL BOTANY OR ORGANOGRAPHY ON THE BASIS OF MORPHOLOGY. TO WHICH IS ADDED THE PRINCIPLES OP TAXONOMY AND PHYTOGRAPHY, *]>L- & logsatg of Botanical BY ASA, GRAY, LL.D., ETC., FISHER PROFESSOR OF NATURAL HISTORY (BOTANY) IN HARVARD UNIVERSITY- NEW YORK : CINCINNATI . : . CHICAGO AMERICAN BOOK COMPANY FROM THE PRESS OF IVISON, Bl.AEKMAN & COMPANY Copyright, BY ASA GRAY. 187. idd'l Farrand Gift LANDSCAPE ARCK. LIBRARY PREFACE. THE first edition of this treatise was published in the year 1842, the fifth in 1857. Each edition has been in good part rewritten, the present one entirely so, and the compass of the work is now extended. More elementary works than this, such as the author's First Lessons in Botany (which contains all that is necessary to the prac- tical study of systematic Phtenogamous Botany by means of Manuals and local Floras), are best adapted to the needs of the young beginner, and of those who do not intend to study Botany comprehensively and thoroughly. The present treatise is intended to serve as a text-book for the higher and completer instruction. To secure the requisite fulness of treatment of the whole range of sub- jects, it has been decided to divide the work into distinct volumes, each a treatise by itself, which may be indepen- dently used, while the whole will compose a comprehensive botanical course. This volume, on the Structural and Morphological Botany of Phgenogamous Plants, properly comes first. It should thoroughly equip a botanist for the scientific prosecution of Systematic Botany, and furnish needful preparation to those who proceed to the study of Vegetable Physiology and Anatomy, and to the wide and varied department of Cryptogamic Botany. 212 IV PREFACE. The preparation of the volume upon Physiological Botany (Vegetable Histology and Physiology) is assigned to the author's colleague, Professor GOODALE. The Introduction to Cryptogamous Botany, both structu- ral and systematic, is assigned to his colleague, Professor FABLOW. A fourth volume, a sketch of the Natural Orders of Phaenogamous Plants, and of their special Morphology, Classification, Distribution, Products, &c., will be needed to complete the series : this the present author may rather hope than expect himself to draw up. ASA GRAY. HERBARIUM OF HARVARD UNIVERSITY, CAMBRIDGE April 10, 1879. into sentences or appended to them, are references to the numbered para- graphs in which the topic is treated or the term explained. CONTENTS. PAGE INTRODUCTION. THE DEPARTMENTS OF THE SCIENCE .... 1 CHAPTER I. OUTLINES OF THE GENERAL MORPHOLOGY OF PHJENOGAMOUS PLANTS 6 CHAPTER II. MORPHOLOGY AND DEVELOPMENT OF THE EMBRYO AND SEEDLING 9 The Embryo, its Nature, Structure, and Parts 9 Development of the Dicotyledonous Embryo in Maple ... 10 In Ipomcea, or Morning Glory, &c., with Albuminous Seeds . 13 In Embryos with thickened Cotyledons 16 As of Almond, Beech, Bean, &c 17 With Hypogaeous Germination and no Elongation of Caulicle 19 In Megarrhiza, &c., with concreted Petioles to the Cotyledons 21 In Ipomoea leptophylla with foliaceous and long-petioled Cotyledons and no elongation of Caulicle 22 In Pumpkin, &c., with no Primary Root 22 The Polycotyledonous Embryo 23 The Monocotyledonous Embryo of Iris, Onion, Cereal Grains 24 Pseudo-monocotyledonous and Acotyledonous Embryo ... 26 Dicotyledonous and Monocotyledonous Plants 27 CHAPTER III. MORPHOLOGY AND STRUCTURE OF THE ORGANS OF THE PLANT IN VEGETATION . . 27 SECTION I. OF THE ROOT 27 Nature, Growth, and Composition 28 Root-hairs 29 Kinds of Roots 29 Duration ; Annuals 30 Biennials 31 Perennials 32 Aerial Roots 33 Epiphytes or Air-plants 35 Parasitic Plants, Green and Colored 36 VI CONTENTS. SECTION II. OF Bui>s 40 Scaly Buds and Bud-scales 40 Naked, Subpetiolar, and Fleshy Buds 41 Bud-propagation 43 Normal, Accessory, and Adventitious Buds 44 SECTION III. OF THE STEM . 45 1. GENERAL CHARACTERISTICS AND GROWTH 45 Development and Structure 46 Ramification, Branches 47 Excurrent and Deliquescent Stems 48 Definite and Indefinite Annual Growth . 49 2. FORMS OF STEM AND BRANCHES 50 Herbs, Shrubs, Trees, Culm, Caudex, Scape 50 Climbing Stems, Twining or otherwise 51 Leaf-climbers, Tendril-climbers, and Root-climbers .... 52 Suckers, Stolons, Offsets, Runners 53 Tendrils formed of Stems 54 Sympodial and Monopodial Stems 55 Spines or Thorns and Subterranean Stems 56 Rhizoma or Rootstock 57 Tuber, Tubercles 59 Corm or Solid Bulb 61 Bulb, Bulblets 62 Condensed Aerial Stems 64 Stems serving for Foliage, Phyllocladia, Cladophylla ... 65 Frondose Stems 66 3. INTERNAL STRUCTURE . 67 Anatomical Elements 68 Endogenous Structure 70 Exogenous Structure ; its Beginning 73 First Year's Growth 74 Pith, Layer of Wood, &c 75 Bark, its Parts and Structure 76 Annual Increase in Diameter 78 Demarcation of Annual Layers . 79 Sap-wood and Heart-wood 80 Growth and Duration of Bark 81 Living Parts of a Tree or Shrub, Longevity 83 The Plant composite 84 SECTION IV. OF LEAVES 85 1. THEIR NATURE AND OFFICE 85 Parts of a Leaf 85 Duration, Defoliation, Normal Position ... 86 CONTENTS. Vii 2. THEIR STRUCTURE AND FORMS AS FOLIAGE 87 Internal Structure or Anatomy 87 Parenchyma-cells 88 Epidermis, Stomata or Breathing-pores 89 Framework, Venation 90 Parallel-veined or Nerved Leaves , . . 91 Reticulated or Netted-veined Leaves 92 Pinnately or Feather-veined and Palmately or Radiately Veined 93 Forms as to Outline 94 Forms as to Extremity 96 Forms as to Margin or Special Outline and Dentation ... 97 Lobation or Segmentation 98 Number and Arrangement of Parts 99 Compound Leaves, Pinnate and Palmate or Digitate, &c. . . 100 Petiole or Leafstalk 104 Stipules, Ligule, Stipels 105 Leaves in unusual Modifications 106 Such as Inasquilateral, Connate, Perfoliate 107 Vertical and Equitant 108 Without distinction of Parts 109 Stipules serving for Blade 109 Phyllodia, or Petioles serving for Blade 110 3. LEAVES SERVING SPECIAL OFFICES 110 Utilizing Animal Matter 110 Ascidia or Pitchers Ill Sensitive Fly-traps 113 Leaves for Storage 115 Bulb-scales and Bud-scales 116 CHAPTER IV. PHYLLOTAXY, OR LEAF-ARRANGEMENT . 119 SECTION I. DISTRIBUTION OF LEAVES ON THE STEM .... 119 Phyllotaxy either Verticillate or Alternate, Cyclical or Spiral 119 Verticillate or Cyclical Arrangement 120 Alternate or Spiral Arrangement 121 Its Modes and Laws 122 Relation of Whorls to Spirals 129 Hypothesis of the Origin of Both 130 Fascicled Leaves 131 SECTION II. DISPOSITION OF LEAVES IN THE BUD 132 Vernation and Estivation; the Modes ........ 132 Direction, Dextrorse and Sinistrorse 140 Vlll CONTENTS. CHAPTER V. ANTHOTAXY OR INFLORESCENCE .... 141 Bracts and Bractlets and their Modifications 141 Peduncles, Pedicels, Rhachis, Receptacle 143 Position of Flower-buds, Kinds of Inflorescence 144 Indeterminate, Indefinite, or Botryose 140 Raceme, Corymb, Umbel 146 Head or Capitulum 147 Syconium or Hypanthodium 148 Spike, Spadix, Ament or Catkin 149 Panicle and other Compound Forms 150 Determinate or Cymose 151 Cyme, Glomerule, &c 152 Botryoidal Forms of Cymose Type 153 Sympodial Forms 154 Scorpioid and Helicoid, the Pleiochasium, Dichasium, and Monochasium 155 Bostryx, Cincinnus, Rhipidium, Drepanium, &c 156 Mixed Inflorescence 158 Thyrsus, Verticillaster, &c 159 Relations of Bract, Bractlet, and Flower 160 Anterior and Posterior, or Inferior and Superior 160 Median and Transverse 160 Position of Bractlets 161 Tabular View of Inflorescence 162 CHAPTER VI. THE FLOWER 163 SECTION I. ITS NATURE, PARTS, AND METAMORPHY .... 163 Floral Envelopes, Perianth, or Perigone 164 The Parts, Calyx and Corolla 165 Androecium, Stamens 165 Gynoecium, Pistils 166 Torus or Receptacle of the Flower 167 Metamorphosis 167 Unity of Type illustrated by Position and Transitions . . . 169 Teratological Transitions and Changes 170 SECTION II. FLORAL SYMMETRY 174 Symmetrical, Regular, and Complete Flower 175 Numerical Ground-plan 176 Pattern Flowers 176 Diplostemonous Type 177 SECTION III. VARIOUS MODIFICATIONS or THE FLOWER . . . 179 'l. ENUMERATION OF THE KINDS 179 2. REGULAR UNION OF SIMILAR PARTS 180 Coalescence or Cohesion 180 CONTENTS. ix 3. UNION OF DISSIMILAR OR SUCCESSIVE PARTS .... 181 Adnation or Connation 182 Hypogynous, Perigynous, Epigynous 183 4 IRREGULARITY OF SIMILAR PARTS 184 5. DISAPPEARANCE OR OBLITERATION OF PARTS .... 187 Abortion or Suppression of Parts of a Circle 187 Abortion or Suppression of whole Circles 190' Terms therewith connected ." 191 Suppressed Perianth 191 Suppressed Androecium or Gynoecium 193 Along with suppressed Perianth 194 Neutral Flowers " . . 195 6. INTERRUPTION OF NORMAL ALTERNATION 195 Anteposition or Superposition 195 In Appearance only 196 Superposition by Spirals 196 Anteposition with Isostemony and Diplostemony 197 With Obdiplostemony 198 7. INCREASED NUMBER OF PARTS 200 Regular Multiplication 200 Parapetalous Multiplication 201 Chorisis or Deduplication 202 8. OUTGROWTHS 209 Their relation to Chorisis : Trichomes 209 Corona or Crown 210 Ligule 211 9. FORMS OF THE TORUS OR RECEPTACLE 211 Stipe, Thecaphore, Gynophore, Carpophore, &c 212 Disk 213 Hypanthium 214 SECTION IV. ADAPTATIONS OF THE FLOWER TO THE ACT OF FERTILIZATION 216 1. IN GENERAL 215 Close and Cross Fertilization, or Autogamy and Allogamy . 216 2. ADAPTATIONS FOR ALLOGAMY OR INTERCROSSING . . . 216 Wind-fertilizable or Anemophilous Flowers ....... 217 Insect-fertilizable or Entomophilous Flowers 218 Irregularity as related to Allogamy 219 CONTENTS. Dichogamy, either Proterandrous or Proterogynous .... 219 Proterogyny . 219 Proterandry 220 Particular Adaptations in Papilionaceous Flowers .... 225 In Kalmia-blossoms, Iris, &c 229 Transportation of Pollinia 230 In Orchidaceae and Asclepiadaeese 231 Heterogonous Dimorphism and Trimorphism 234 3. ADAPTATIONS FOR CLOSE FERTILIZATION 240 Cleistogamy 241 SECTION V. THE PERIANTH, OR THE CALYX AND COROLLA IN PARTICULAR 243 Perianth as to Duration, Numerical Terms, Union, &c. . . . 243 Parts of Petals and of Gamophyllous Perianth 245 Forms of Corolla and Calyx 246 SECTION VI. THE ANDRGECIUM, OR STAMENS IN PARTICULAR . 249 The Stamen as a whole ; Numerical Terms 249 The Filament and the Anther ; their Modifications .... 251 Pollen 256 Pollen-tubes 258 SECTION VII. THE PISTILS, OR GYNOSCIUM 259 1. IN ANGIOSPERMS 259 Carpel or Carpophyll 260 Ventral and Dorsal Sutures ; Placenta 261 Simple or Apocarpous Pistils 262 Compound or Syncarpous Pistil 263 With two or more Cells and Axile Placentae ; Partitions . . 264 With one Cell and Parietal Placentae 265 With one Cell and Free Central Placenta 266 Anomalous Placentation 267 2. IN GYMNOSPERMS 268 Structure in Gnetaceae 269 Structure in Coniferae 270 In the Yew Family 271 In the Pine Tribe, &c 272 In the Cypress Tribe 273 Structure in Cycadaceas 274 SECTION VIII. THE OVULE 276 Its Structure and Position 277 Its Forms, Orthotropous, Campylotropous, Amphitropous, Anatropous 278 Origin and Morphological Nature of the Ovule 282 Origination of the Embryo 283 CONTENTS. "xi CHAPTER VII. THE FRUIT 285 SECTION I. ITS STRUCTURE, TRANSFORMATIONS, AND DEHIS- CENCE 285 Pericarp, its Alterations, Accessions, and Transformations . 287 Dehiscence 288 SECTION II. THE KINDS OF FRUIT 291 Simple Fruits 291 Dehiscent Fruits, Follicle, Legume, Capsule, Pyxis, Silique . 292 Indehiscent Dry Fruits, Samara, Akene, Utricle, Caryopsis, Nut, &c 294 Fleshy Fruits, Drupe, Pome, Pepo, Berry, &c 297 Aggregate Fruits 299 Accessory or Anthocarpous Fruits 300 Multiple or Collective Fruits, Syconium, Strobile, &c. . . . 301 Table of Simple Fruits 304 CHAPTER VIII. THE SEED 305 Its Stalk, Coats, and Appendages 306 Aril or Arillus 308 Nucleus or Kernel, Albumen 309 The Embryo, its Parts and Positions 311 The Cotyledons as to Adjustment arid Number 313 CHAPTER IX. TAXONOMY 315 SECTION I. THE PRINCIPLES OF CLASSIFICATION IN NATURAL HISTORY 315 Individuals 315 Species 317 Varieties, Races, &c .' 318 Cross-breeds and Hybrids 321 Genera 323 Orders, Classes, Tribes, &c 325 Sequence of the Grades 327 Nature and Meaning of Affinity 327 Theory of Descent and Natural Selection 328 SECTION II. BOTANICAL CLASSIFICATION 331 Ante-Linnaean Classifications 332 Linnaean Classification 333 Sexual Artificial System 334 Natural System 338 As presented by Jussieu 339 Some of its Modifications , . 340 Xil CONTENTS. CHAPTER X. PHYTOGRAPHY 345 SECTION I. NOMENCLATURE 345 Names of Plants, Binomial Nomenclature 346 Rules for naming Plants 347 Names of Genera 348 Names of Species, Varieties, &c 350 The Fixation, Precision, and Citation of Names 352 Subgeneric Names 356 Tribal and Ordinal Names 357 Names of Cohorts, Classes, &c 358 SECTION II. GLOSSOLOGY OR TERMINOLOGY 359 SECTION III. DESCRIPTION 861 Characters 361 Punctuation 364 Synonomy 365 Iconography 366 Habitat and Station, &c 366 Etymology of Names 366 Accentuation, Abbreviations 367 Signs 368 Floras, Monographs, &c 369 SECTION IV. SPECIMENS, DIRECTIONS FOR THEIR EXAMINA- TION, PRESERVATION, &c 370 Implements of Investigation 370 Diagrams 371 Herborizing 371 Drying Specimens 375 Poisoning Specimens 379 The Herbarium 380 ABBREVIATIONS 385 SIGNS 391 GLOSSARY OF BOTANICAL TERMS, WITH INDEX . . 393 STRUCTUBAL BOTANY THE BASIS OF MORPHOLOGY. INTRODUCTION. 1. THE two Biological Sciences, 1 considered as parts of Natural History, are Zoology and Botany. The latter is the natural history of the Vegetable Kingdom. It embraces every scientific inquiry that can be made respecting plants, their nature, their kinds, the laws which govern them, and the part they play in the general economy of the world. 2. We cannot distinguish the vegetable from the animal king- dom by any complete and precise definition. Although ordinary observation of their usual representatives may discern little that is common to the two, yet there are many simple forms of life which hardly rise high enough in the scale of being to rank dis- tinctively either as plant or animal ; there are undoubted plants possessing faculties which are generally deemed characteristic of animals ; and some plants of the highest grade share in these endowments. But in general there is a marked contrast between animal and vegetable life, and in the part which animals and plants respectively play in nature. 3. Plants only are nourished upon mineral matter, upon earth and air. It is their peculiar office to appropriate mineral mate- rials and to organize them into a structure in which life is mani- fested, into a structure which is therefore called organic. So the material fitted for such structure, and of which the bodies 1 Biology, the science of life, or rather of living things, in its earlier use was equivalent to physiology : recently, it has come to denote the natural history of plants and animals, t. e. of the two organic kingdoms, including both their physiology and descriptive natural history. 1 2 INTRODUCTION. of plants and animals are composed, is called organic matter. Animals appropriate and live upon this, but have not the power of producing it. So the vegetable kingdom stands between the mineral and the animal ; and its function is to convert materials of the one into food for the other. Although plants alone are capable of building up living structure out of mineral mate- rials, and are the sole producers of the organic matter which is essential to animal life, and although animals consume that which plants produce, yet plants also consume organic matter, more or less, acting in this respect like animals in all their opera- tions, except in the grand and peculiar one by which they assimilate mineral matter. Most plants of the higher grades assimilate largely and consume little, except in special opera- tions. Some, on the contrar} r , are mainly consumers, and feed upon formed organic matter, living in this respect after the manner of animals. The living substance of plants and animals is essentially the same. 4. Botany deals with plants : 1. As individuals, and in respect to their structure and functions. 2. In their kinds, and as respects their classification, nomenclature, &c. Accordingly, the most comprehensive division of the science is into PHYSIO- LOGICAL or BIOLOGICAL BOTANY (using these terms in their widest sense) and SYSTEMATIC BOTANY. But as Plrysiolog}' and Biology, in the restricted sense, relate only to functions or actions and their consequences, the first department naturally divides into two, viz. Structural Botany and Physiology. o. STRUCTURAL BOTANY comprehends all inquiries into the structure, the parts, and the organic composition of vegetables. This is termed ORGANOGRAPHY, when it considers the organs or obvious parts of which plants are made up, and MORPHOLOGY, when the study proceeds on the idea of type. The term ORGANOGENY has been applied to the study of the nascent organs and their development; PHYTOTOMY, or VEGETABLE ANATOMY, to that of the minute structure of vegetables as re- vealed by the microscope, i. e. to the composition of the organs themselves. But, since anatomy in the animal kingdom includes the consideration of general as well as of minute structure, and indeed answers to organograplrv, the minute anatomy of both kingdoms takes the special name of HISTOLOGY. The study of functions, or of the living being (animal or plant) in action, is the province of PHYSIOLOGY. G. SYSTEMATIC BOTANY, or the study of plants in their kinds and in regard to their relationships, comprises TAXONOMY, or the principles of classification, as derived from the facts and ideas INTRODUCTION. S upon which species, genera, &c., rest; CLASSIFICATION or the SYSTEM OF PLANTS, the actual arrangement of known plants in systematic order according to their relationships ; PHYTOGRAPHY, the rules and methods of describing plants ; and NOMENCLATURE, the methods and rules adopted for the formation of botanical names. GLOSSOLOGY or TERMINOLOGY 1 is a necessaiy part of Phytography or Descriptive Botany, and hardly less so of Structural Botany: it relates to the application of distinctive terms or names to the several organs or parts of plants, and to their numberless modifications of form, &c. This requires a copious vocabulary of well-defined technical terms, b}' the use of which the botanist is able to describe the objects of his study with a precision and brevity not otherwise attainable. It will be convenient to exemplify the principal terms along with the modifications of conformation which they designate ; and also, for greater fulness and facility of reference, to append to this volume an alphabetical summary of them, or Vocabulary of Botanical Term s . 2 7. The present volume is mainly devoted to Morphological Botany ; that is, to Structural Botany on the basis of mor- phology. This department cannot be properly dealt with apart from considerable reference to intimate structure, development, and function, the subject-matter of vegetable histology and physiology. But these will here be treated only in the most general or incidental and elementary way, and only so far as is necessary to the understanding of the morphology of the stem, leaves, &c. The whole discussion of the histology and physiology of plants is relegated to a following volume and to another hand. 8. The most comprehensive and important division of the vegetable kingdom is into plants of the higher and of the lower series or grade, i.e. into PH^NOGAMOUS (or PHANEROGAMOUS) or FLOWERING, and CRYPTOGAMOUS or FLOWERLESS PLANTS. The first are all manifestly of one type, and therefore have a consist- ent and simple morphology. The second differ among them- selves almost as widely as they do from the higher series ; and 1 GLOSSOLOGY is the better word, but TERMINOLOGY, although a hybrid of Latin and Greek, is in common use. 2 What is called GEOGRAPHICAL BOTANY is the study of plants in respect to their natural distribution at the present time over the earth's surface, and the causes of it. FOSSIL BOTANY (Vegetable Palaeontology) relates to the plants of former ages, as more or less made known in their fossil remains. MEDICAL BOTANY, AGRICULTURAL BOTANY, and the like, are applications of Botany to medicine, agriculture, &c. 4 INTRODUCTION. their morphology is more special and difficult. Wherefore it is better to treat them separately and subsequently. This will be done in a third part, by an associate devoted to Cryptogamic Botany. 9. Thus the field is here left clear for the Structural Botany of Phaenogarnous or Flowering Plants, with which the study of the science should naturally begin. In theory it may seem proper to commence with the simplest plants and the most ele- mentar}- structures ; but that is to put the difficult and recondite before the plain and obvious. The t}*pe or plan of the vegetable kingdom, upon which morphological botany is grounded, is fully exemplified only in the higher grade of plants, is manifest to simple observation, and should be clearly apprehended at the outset. CHAPTER I. OUTLINES OF THE GENERAL MORPHOLOGY OF PH^ENOGAMOUS PLANTS. 10. MORPHOLOGY, the doctrine of forms, as the name denotes, is used in natural history in nearly the same sense as the older term Comparative Anatomy. If it were concerned merely with the description and classification of shapes and modifications, it would amount to little more than glossology and organography. But it deals with these from a peculiar pmnt of view, and under the idea of unity of plan or type. 1 11. As all vertebrate animals are constructed upon one type (or ground plan) , which culminates or has its archetype in man, so all plants of the higher grade (8) are strictly of one type ; the different kinds being patterns or repetitions of it, with varia- tions. The vegetable kingdom, however, does not culminate in an archet} T pe or highest representative. As respects the organs of vegetation, the higher classes of cryptogamous plants exhibit this same type ; but it is only in the most general or in a recondite sense that this can be said of their organs of repro- duction, and of the less differentiated structure of the lowest classes. Wherefore ciyptogamous plants are left out of the present view, to be treated apart. 12. Viewed morphologically and as to its component organs, a plant is seen to consist of an axis or stem, which sends off roots into the soil, and bears lateral appendages, commonly as leaves, but which may be very unlike leaves in whole appearance 1 The term Morphology was introduced into science by Goethe, at least as early as the year 1817 (Zur Naturwissenschaft uberhaupt, besonders zur Morphologic, Stuttgart und Tubingen, 1817-24). On page 9 of the first volume, he is understood to have suggested this word for the purpose and in the sense now adopted in botany and zoology. It essentially replaces an earlier and somewhat misleading word, Metamorphosis. (304.) Apparently the first botanist to adopt the term was Auguste de St. Hilaire, in his " Lemons de Botanique, comprenant principalement la Mor- phologie Vegetale, etc., Paris, 1841. The term seems not to have been taken up, in zoology, by Etienne Geoffrey Saint-Hilaire, the antagonist of Cuvier (who was of a wholly different family from that of the botanist), although the same idea was denoted by his phrase " unity of organic composition " 6 GENEKAL MOKPHOLOGY and function. These appendages, whatever their form or use, accord with leaves in mode of origin, position, and arrangement on the axis or stem. Their most general and ordinary form is the familiar one of foliage ; hence the name of leaves has been by botanists extended in a generic way from the green expan- sions which constitute foliage to other forms under which such appendages occur. The proper morphological expression is, that the latter are homologous with leaves, or are the homologues of leaves. 1 13. Leaves are borne upon the stem at definite places, which are termed NODES. A node may bear a single leaf or a greater number. When it bears two, they occupy opposite sides of the stem. When three, four, or more, they divide the circum- ference of the stem equally, forming a circle, technically a WHORL, or in Latin form a VERTICIL. When only two, the pair evidently answers to the simplest kind of whorl. So that leaves are either single on the nodes, in which case they are alter- nate, that is, come one after another on the stem ; or in whorls (whorled, verticillate) , in the commoner case of a single pah- being called opposite. The bare space between two successive nodes is an INTERNODE. This is longer or shorter, according to the amount of longitudinal growth, which thus spaces the leaves, or whorls of leaves, in most .various degrees, either widely when the internodes are elongated, or slightly when they remain very short. The plant, therefore (roots excepted) , is made up of a series of similar parts, i. e. of portions of stem, definitely bearing leaves, each portion developed from the apex of the preceding one. This constitutes a simple-stemmed plant. 14. Branching is the production of new stems from the older or parent stem. These normally appear in the AXILS of leaves, that is, in the upper angle which the leaf forms with the stem, from which they grow much as the primary stem grew from the seed. The primary stem, connected with the ground, produces roots which develop downwardly into the soil, from which they draw sustenance. Branches, when developed above ground, 1 A common designation for all these appendages being desirable, a good one is furnished by the Greek name for leaf, tyvXXov, PHYLLI M, plural PHYLLA. This, used with prefixes, may be made to designate the kind of leaves in many cases, as, prophylla, cataphi/lla, hgpxojtkylla. Recent German botanists use the word Phyllome. in this sense. It is a rather convenient and well sounding word ; but pkylloma is the exact Greek equivalent of our word foliage, and therefore not very well chosen as a common term for leaves which are not foliage as well as those which are. Nor will this word, like phi/Hum, readily take prefixes, as above, or the adjec- tive form, as it readily does in prophyllous, hyi>sophyllous, cjamophyllous, e. OF PH^ENOGAMOUS PLANTS. being in organic connection with their parent stem, do not usually produce roots ; but when placed in equally favorable conditions for it, i. e. on or in the soil, they may strike root as freely as does the original stem. 15. An incipient stem or branch, with its rudimentary leaves, is a BUD. The normal situation of a bud is in the axil of a leaf (axillary) , the development giving rise to branches ; or else at the apex of an axis (terminal), where there can be only one, the development of which continues that axis. 1 16. As branches are repetitions and in one sense progeny of the stem which bears them, so the serial similar parts or leaf- bearing portions of a simple stem are repeti- tions, or in a like sense progeity, each of the preceding one from which it grew. The simple-stemmed plant is made up of a series of such growths, each from the summit of its predecessor ; the branched plant, of ad- ditional series, laterally developed, from ax- illary buds. These ultimate similar parts into which a plant may thus be analyzed, and which are endowed with or may produce all the fundamental organs of vegetation, were by Gaudichaud called PHYTONS. But phyton, being the common Greek name for plant, was not a happily chosen appellation for plant- elements, or homologous plant-units. A better term for them is PHYTOMERA (qivrov, plant, jM

n above is the caulicle. 12 MORPHOLOGY After this is consumed and in good part converted into struc- ture, the plantlet must by the action of its root and leaves imbibe from the soil and air appropriate materials, and assimilate them into nourishing matter needful for further growth. Only then does the rudi- ment of new structure appear, in the form of a growing point, or bud, at the node or apex of the primitive stemlet, between the two seed- leaves. In this case it soon shows itself as a second pair of leaves, at first resting on the node (Fig. 9), next as somewhat upraised by the development of the second internode (Fig. 10, summit), and finally both this inter- node and the pair of leaves complete their growth (Fig. 11). Then the terminal bud which crowns the second node develops in the same way the third pair of leaves and their supporting internode or joint of stem (Fig. 12) ; and so on. 24. The root and the stem grow not only in opposite directions, but in a different mode. The primordial stem, pre-existing in the seed (though at first it may be extremely short) grows throughout its whole length, but most in its upper part, so that it may become a stemlet two or three inches long. But, soon attaining its full growth as to length, the stem is carried upwards by the subsequent joints or portions, similarly developed and elongated, one after the other. Not that each portion necessarily waits until the growth of its prede- cessor is complete, though this occurs at first in seedling Maples and other embryos unprovided with much store of food, yet the development follows this course and order of succession. The root, on the contrary, cannot be said to pre-exist in the seed, or at most it ma}~ be said to exist potentially in tissue of the caulicle from which a root or roots normally originate. 1 It is formed 1 Yet from nothing which is special to this part of the embryo, nor to the embryo at all. The primary root is developed from subjacent tissue of the tip of the caulicle, just as it is sometimes developed from along the sides, and as secondary roots are from all or most stems under favoring conditions. This complete similarity, and the fact of what is called the " endogenous " origin of roots (i,e. their springing from subjacent rather than superficial tissue) appear fully to warrant the statement in the text above. FIG. 10. Maple plantlet with second internode developing. 11. Same with second, internode an:l rxiir of leaves co:in5ete, and bud of the third apparent. OF THE EMBRYO AND SEEDLING. 13 in the process of germination, and originates in tissue just back of that which covers the root-end of the caulicle, and which, being carried forward by the subjacent formation (to which it becomes a sort of cap or sheath) , is called the Root-cap. As the primary root thus began by a new and local growth at the extremity of pre-existing stem, so it goes on to grow in length wholly or mainly by a continuation of this formation, the new at the end of the old. That is, the root elongates by continual minute increment of its apex or near it, the formed parts very soon ceasing to lengthen. This is in marked distinc- tion from stem, which grows by suc- cessive individualized portions ; and these portions (internodes) , at first very short, attain or are capable of attaining a considerable and sometimes very great, but definitely terminable length, by interstitial growth through- out. Moreover, roots are naked, not producing as they grow either leaves or any organs homologous with leaves. The} T commonly branch or divide, but in a vague manner ; and their new parts bear what are called Root-hairs, which greatly increase the absorbing surface ; other- wise they are destitute of appendages or organs. 25. With the Maple embryo, here taken as a type, that of Morning Glory, Ipomcea purpurea, or any of its kin, may next be compared. The cot}'ledons are different in shape, being as broad as long, and notched both at base and apex. They lie in contact in Fig. 14, and are very thin, leaf-like, and green while contained in the seed. Their thinness is shown in Fig. 13, where a section of the crumpled and folded embryo, as it lies in the seed, exactly divides them (passing through the terminal and basal notches) and also the caulicle, which here is thicker than both. The germination is similar to that of the Maple ; and like that (as Fig. 16 shows), and for the same reason, no bud or rudiment of the further growth pre-exists in the embryo or FIG. 12. Red Maple seedling, with throe joints of stem and pairs of leaves developed, the first being the cotyledons. MORPHOLOGY appears in the young plantlet, until that has established itself and had time to elaborate proper material therefor. This con- dition is correlated with thin foliaceous cotyledons, holding no store of nourish- ment. Here they do not contain sufficient material for the development of the initial stem and root. The maternal provision for this is here stored up in the seed around but not within the embryo. This nourishing deposit, seen in the section (Fig. 13) filling the whole space between the seed-coats and the thin embryo, was named by the early botanists and vege- table anatomists the ALBUMEN of the seed. 1 This substance, softened in germination and by chemical changes rendered soluble, is gradually absorbed by the cotyledons as material for their growth and that of the developing primary stem and root. 26. Seeds in this regard are accordingly distinguished into albuminous and exal- buminous, those supplied with and those destitute of albumen. The difference inheres neither in the character nor in the amount of the maternal provision for the development of the embryo-plant, but merely in the storage. In exalbuminous seeds the nourishment supplied for this purpose is taken into the embr} T o itself, mostly into the cotyledons, during the growth and before the maturity of the seed. In albuminous seeds this same material is deposited around or at least external to the embryo. 27. The amount of this deposit is, in the main, inversely pro- 1 Grew appears to have first applied this name, and Gaertner to have introduced it into systematic botany, where it remains in use, although Jussieu replaced it by the term Perisperm, and Richard by Endosperm, neither of them much better etymologically than the old word Albumen. But it must be kept in mind that it was intended to liken the " albumen " of the seed with the albumen or white of an egg as a body or mass, and not as a chemical substance; the embryo being fancifully conceived to be analo- gous to the yolk of the egg, the surrounding substance of this kind not unnaturally took the name of the white, viz. albumen. FIG. 13. Section of seed of common Morning Glory, Ipomoea purpurea, dividing the contained embryo through the centre. 14. Embryo of same, detached and straight- ened. 15. Embryo in germination ; the cotyledons only partly detached from the coat of the seed. 16. Same, later and more developed, the cotyledons unfolded and out- spread as the first pair of leaves. OF THE EAIBKYO AND SEEDLING. 15 portional to the size and strength of the embiyo, or the degree of its development in the seed. A comparison of the various illustrations sufficiently shows this. Figures 17 to 24 exhibit, in a few common seeds, somewhat of this relation, and also of the position and shape assumed in some instances. The tipper rank of figures represents sections of seeds ; the embiyo left in white ; the albumen as a dotted surface. The lower rank shows the embryos detached. That of Mirabilis has very broad and thin cot}'ledons, a caulicle of equal length, and the whole curved round the albumen which thus occupies the centre of the seed. That of Potato is coiled in the midst of the albumen, is slender ; the cotyledons narrowed down to semi-cylindrical bodies, not leaf-like in appearance, and the two together not thicker than the caulicle. In Barberiy the embiyo is straight, in the axis of the albumen, which it almost equals in length ; the cotyledons considerably broader than the caulicle, but short and thickish. That of the Peony is similar, but very much smaller, occupying a small space at one end of the albu- men, and seemingly without distinction of parts, but under the microscope and with some manipulation the broader end is found to be divided, that is, to consist of two minute cotyledons. The embiyo of a Crowfoot is similar, but still more minute and the parts hardly to be distinguished ; and in some minute em- bryos there is no apparent distinction of parts until they develop in germination. 28. The study of the formation of the embryo in the seed teaches that all embryos begin with a still more simple, minute, and homogeneous structure ; and these comparisons suffice to show that all such differences are referable to different degrees and somewhat different modes of the development of the embiyo while }-et in the seed. It also appears that the size and shape FIG. 17. Section of seed and contained embryo of Mirabilis (Four-o-clock). 18. Embryo detached entire. FIG. 19. Section of a Potato-seed. 20. Embryo detached entire. FIG. 21. Section of Barberry-seed. 22. Embryo det.ac.hed entire. FIG. 23. Section of Peony-seed. 24. Embryo detached entire. 16 MOKPHOLOGY of an organ do not indicate its nature, either in the embn^o or in subsequent growth. But in all the cases } T et mentioned the cotyledons actually demonstrate their nature by developing in germination in a foliaceous manner and becoming the first leaves of the seedling. Nor is this nature much disguised by the fact that they differ greatly in form in different species, and that the seed- leaves, or developed cotyledons, differ much in shape and often in texture from the succeeding leaves. (See Fig. 11, 12, 25, &c.) 29. To complete the comparison between the seedling Morning Glory and that of the Maple, it is to be noted that here, while the cotyledons or seed-leaves are two, the following internode bears only one leaf (Fig. 25), as also will the just de- veloping third internode ; and this continues throughout up to the blossom : that is, the leaves subsequent to the cotyledons are not opposite as in the Maple, but alternate. (13.) 30. All the preceding illustrations are from embryos w r hich previous to germination have developed nothing beyond the cotyledons. In the following, a rudiment of further growth, or a primary terminal bud, is visible in the seed. It is most manifest in large and strong embryos with thick or fleshy cotyle- FIG. 25. Further development of Morning Glory, Fig. 1G, the root cut away, the internode above the cotyledons and its leaf completed, the next internode and its leaf appearing. FIG. 26. Embryo (kernel) of the Almond. 27. Same, with one cotyledon removed, to show the plumule, a. FIG. 23. Section of an Apple-seed, magnified, cutting through the thickness of the cotyledons. i>9. Embryo of the same, extracted entire, the cotyledons a little separated. FIG. 30. Germination of the Cherry, showing the thick cotyledons little altered, and the plumule developing the earliest real foliage. OF THE EMBRYO AND SEEDLING. 17 dons, i. e. cotyledons well charged with nourishing matter. The early vegetable physiologists gave to it the name of PLUMULE (Lat. plumula, a little plume). The K t name was suggested by its appearance in such an embr3'o as that of the bean (Phaseolus), in which it evidently con- sists of a rudimentary pair of leaves, while in the pea and the acorn it is a rudimentary stem, the leaves of which appear only later, when germination has considerably advanced. In any case, the plumule is the bud of the ascending axis already discernible in the seed. Fig. 27, a, shows it in the almond, one cotyledon being removed. Fig. 28 shows it in the section of a similar although much smaller embryo, that of an apple-seed, enlarged to nearly the size of the other. It is equall}' visible in the cherry, the bean, and the beechnut. The embryo in all these cases constitutes the whole kernel of the seed. For the nourishment, which in all the foregoing illustrations except the first (i.e. in Fig. 13, 17-23), is deposited around or exterior to the embiyo, is in these stored within it. 31. The development of these em- bryos in germination proceeds in the normal manner, but with two cor- related peculiarities. First, b} r the lengthening of the radicle more or less, their thick cotyledons are usually raised to or above the surface of the soil ; they expand, assume the green color needful to foliage ; but the}' imperfectly or in a small degree perform the function of green leaves. Their main office is to supply the other growing parts with the prepared nourishment which they abundantly contain. Then, being thus copiously nourished, the root below and the read3'-formed plumule above grow rapidly and strongly, having accumulated capital to draw upon ; and the leaves of the FIG. 31. Beechnut cut across, filled by the fli shy embryo; the thick cotyledons partly enfolding each other. 32. Embryo of the same in early germination 33. Same more advanced; the plumule, which is just emerging in the preceding, here developed into a long internode and a pair of leaves. . 2 18 MORPHOLOGY latter are practically the earliest efficient foliage of the plantlet. Thus, as in the germinating Cheny-seed (Fig. 30) , three or four internodes of stem, with their leaves, ma}^ be produced before these leaves themselves are sufficiently developed to make any sensible contribution to this growth. And in the Beech and Bean, the leaves of the plumule come forward almost before the root has attached the plantlet to the soil. (Fig. 32, 35.) Between such cases and that of Maple and the like there are all degrees. There are also familiar cases in which the storage of nourishment in the cotyledons is carried to a maximum, with results which gravely affect the development. FIG. 34. The embryo (the whole kernel) of the Bean. 35. Same early in germi- nation ; the thick cotyledons expanding and showing the plumule. 36. Same, more advanced in germination ; the plumule developed into an internode of stem bearing a pair of leaves. FIG. 37. Embryo of Pea, i. e. a pea minus the seed-coat. 38. Advanced germi- natior of the same. OF THE EMI3KYO AND SEEDLING. 19 32. Thus, in the Pea, near relative of the Bean, the embryo (Fig. 37), which is the whole kernel of the seed, has the cotyledons so gorged with this nutritive store that they are hemispherical ; and the acorn of the Oak (Fig. 39), near relative of the Beech, is in similar case. These extremely obese cotyledons have not only lost all likeness to leaves, but all power of fulfilling the office of foliage, which is apparently no disadvantage ; for when two different duties are performed by the same organ, it rarely performs both equally well. Here they become mere receptacles of prepared food, the nature and office of which is the same as of the albumen, or nutritive deposit exterior to the embryo in what are called albuminous seeds. (25-27.) The difference is in the place rather than in the character of the deposit. The plumule in such cases is always apparent before germination ; and it develops even with more vigor than in the preceding cases. It usually rises as a stout stem of several internodes lengthen- ing almost simultaneously, or at least the upper strongly developing long before the lower have finished their growth ; and the latter are practically leafless, bearing only small and scale-like and useless ru- diments of leaves. This is correlated with the peculiarity that the caulicle does not lengthen in germination, or it lengthens very slightly ; the cotyledons remain within the coats of the seed ; and if this were ^ buried beneath the surface of the ground, there it remains. The abortion of the earliest leaves of the plumule is in correlation with this hypogceous (i. e. underground) situation of the cotyle- dons throughout the germination. The slight elongation of the caulicle S3rves merely to protrude its root-end from the coats of the seed in a downward direction, and from this a strong root usually is formed. FIG. 39. Section of an acorn, filled by the embryo. 40. Advanced germination oi the same. 20 MOIU'HOLOGY 33. In some Oaks, notably in our Live Oak (Quercus virens), and less so in the Horsechestnut, the two cotyledons coalesce or cohere by their contiguous faces. In some of these cases of hypo- gaeous germination, the short caulicle and plumule are extri- cated from the enclosing coats or husk by the development of short stalks (petioles, 157) to the fleshy cotyledons ; as is seen in Fig. 42, and in most germinating acorns. These petioles are not visible in the seed, but are the first develop- ment in germination. 34. There are some curious cases in which, while the caulicle remains short and subterranean, the cotjledons are raised out of ground in germination by the formation of far longer stalks (petioles) than those of the Horsechestnut. A singularl}* dis- guised instance of this kind is seen in Megarrhiza, a genus of Cucurbitaceous plants of California and Oregon, remarkable for their huge root. The large seed has very thick and fleshy cotyledons, and a veiy short and straight caulicle. In germi- nation, the whole seed is elevated, seemingly in the manner of tli2 bean, upon a stout stem. One waits for a long time expect- ing to see the cotyledons throw off the bursting husk and expand, or else to put forth the plumule from between their bases. But at length the plumule makes its appearance from an unexpected place, coining separately out of the soil. Removing this, the state of things represented in Fig. 43 is presented, that of the plumule seemingly originating from the base, instead of the apex, of an elongated caulicle ! But on examination of the cleft from which this proceeds, by making a section of the stem above (showing that it is hollow) , and finally by separating the cotyle- dons and gently tearing apart the two short stalks by which the}' are united to their stem-like support, it is found that the latter may be divided into two (as shown in Fig. 44) , even down to the cleft below. This explains the anomaly. The real caulicle has re- FIG. 41 Section of a Horsechestnut or Buckeye seed, through the very thick cotyledons and the incurved caulicle 42. Seed in germination, showing the petioles to the cotyledons, &c. OF THE EMBRYO AND SEEDLING. 21 mained short and subterranean, and is confluent with the upper part of the thickening root : the seeming caulicle, which raised the cot} T ledons above the soil, consists of the petioles of these combined into a tubular stem-like body, no evident trace of which is visible in the seed, although in germination it attains the length of two or three inches : in age it is readily separable into the two leaf-stalks or petioles of which it is composed : the plumule is thus seen to be wholly normal, originating from between the cotyledons. All the ex- tensive growth so far, and until the proper foliage-leaves of the continu- ation of the plumule are developed and begin their action, is from nutri- tive material stored in the thickened cotyledons, a considerable part of which was transferred to the already enlarging root, before a remaining portion was used in building up the strong plumule. The economy of this elevation of cotyle- dons which never open, and of the lengthened distance through which the nutritive matter has to be carried, is not apparent. But it is the family habit in Cucurbitacese to bring up the cotyle- dons that they ma} r develop as leaves (as in the Pumpkin, Fig. 47) : here this elevation is brought about in a different waj', but without securing the useful end. 1 1 It may be inferred that Megarrhiza is a descendant of some Cucurbitacea with thinner cotyledons, which in germination developed into long-stalked leaves, in the manner described in the next following paragraphs. FIG. 43, 44. Peculiar germination of Megarrliiza California! ; explained above. 22 MORPHOLOGY 35. This same anomaly, as to the development of long stalks to the cotyledons and their union into a stem-like bod}', occurs in various species of Larkspur (notably in the Californian Delphin- ium nudicaule) ; but in these the cotyledons develop into a pair of efficient green leaves. 45 47 36. A similar elongation of petioles of the cotyledons, but without any union, occurs in a species of Morning Glory of the plains beyond the Mississippi (Ipomcea leptophylla) ; the leaf- like cotyledons coming up on their long stalks separately from the ground (Fig. 45) ; the developed plumule rising some time afterward between them. Compare this with the ordinary species (25, Fig. 15, 16, 25), and note that the difference is merely that the caulicle in the common Morning Glory elongates and the petioles of the cotyledons remain short. 37. In all instances thus far a single primar} r root so regularly develops from the lower end of the axis of the embryo (variously named radicle or caulicle) , and forms such a direct downward FIG. 45. Germination of Ipomoea leptophylla; the caulicle not developing, the plumule and the petioled cotyledons rise from underground. Dotted line marks the level of the soil. FIG. 46. Embryo of a Pumpkin, the cotyledons separated. 47. Same germinated; a cluster of roots from the base of caulicle. OF THE EMBRYO AND SEEDLING. 23 prolongation of it, that it was called the descending axis ; and the body from which it originates was named the radicle, on the supposition that it was itself the nascent root. But, as already explained, the so-called radicle grows in the manner of stem (24), and is morphologically that initial internode the node of which Dears the first leaves or cotyledons. (20.) Let it now be noted that this descending axis or single primary root is far from universal. In Pumpkin, Squash, Echinoc}'stis, and the like, the strong caulicle sends out directly from its root-end a cluster of roots or rootlets, of equal strength; i. e., it strikes root in nearly the manner that a cutting does. (Fig. 47.) 38. The Polycotyledonous Embryo is one having a whorl of more than two seed-leaves. The dicotyledonous embryo being a whorl of the very simplest kind, that is, with the members reduced to two, the poly cotyledo nous may be regarded as a variation of it. In all but one group of plants it is simply a variation, of casual occurrence, or even a monstrosity, in which three or rarely four cotyledons appear instead of two. In Pines (Fig. 48, 49), however, and in most but not all Coniferse, a whorl of from 3 to 10 cotyledons is the normal structure, va^-ing accord- ing to the species, but of almost uniform number in each. In germination these are brought out of the soil by the elongation of the caulicle, and when the husk of the seed is thrown off they expand into a circle of needle-shaped leaves. In the Pine tribe, all the subsequent leaves are alternate (spiral) in arrange- ment, with some disguises. In the C}'press tribe, the cot3 T ledons are fewer (not more than four, and more commonly only two), and the subsequent leaves also are in whorls of two to four ; i. e., are either opposite or verticillate. From the occasional union at base of the cotyledons of a polycotyledonous embryo in pairs or groups, and from a study of their earl} 7 development, Duchartre 1 plausibly maintains that such cotyledons realty consist of a single pair, parted into divisions or lobes. The ordinar}' interpretation, however, is equally tenable. 39. The Monocotyledonous Embryo, although theoretically the simplest, is practically a more difficult stud}'. It has a single cotyledon (as the name denotes) ; also a single leaf to each node 1 Ann. Sci. Nat. ser. 3, x. 207. This view, which originated with Jussieu, is adopted by Parlatore in DC. Prodr. xvi. FIG. 48. Section of a seed of a Pine, with its embryo of several cotyledons. 49. Early seedling Pine, with its stemlet, displaying its six seed-leaves. MORPHOLOGY 64 of the plumule ; that is, the leaves of the embryo are alternate. But the caulicle is usually very short, and there is no external mark by which its limits may be distin- guished from the cotyledon, until germi- nation has begun. For a type of it, the embryo of some aquatic or marsh plants \i \ // |Nj2>d| may be taken, where it forms the whole kernel of the seed (Fig. 50-53), and 50 si 52 53 the structure can be made out antecedent to germination. It is understood by supposing that the cotyle- don, which forms its principal bulk (the caulicle being only the very short thickish base) , is convolute around a short plumule, and the margins concreted, except a minute longitudinal chink at base, out of which the growing plumule protrudes in germination. The embryo of Iris may be similar in structure, but no distinction of parts is visible. It is very small in proportion to the size of the seed, the kernel being mostly albu- men, a supply of food, from which the germinating embryo draws the materials of its growth. When this takes place, either the cotyledon or the whole embryo lengthens, its lower part is pushed out of the seed, a root forms at the free end of the excessively short caulicle, and the plumule develops from the other in a series of one-leaved nodes, the internodes of which remain so short that the leaves continue in close contact, the bases of the older successively enclosing the inner and younger. (Fig. 55.) Here, therefore, the cotyledon mainly remains in the seed, and the seed remains underground (Irypogseous) . 40. It is somewhat different in the Onion, which has a similar embryo, except that it is longer, and the cotyledon is curved in the albumen of the seed. The first steps are the same as in Iris ; but as soon as a root is formed and embedded in the soil, the cotyledon lengthens vastly more, into a long and filiform green leaf, which, taking an erect position, FIG. 50. Seed of Triglochin palustre ; the rhaplie, leading to the strong chalaza at the summit, turned towards the eye 51. The embryo detached from the seed-coats, showing the longitudinal chink at the base of the cotyledon ; the short part below is the radicle. 52. Same, with the chink turned laterally, and half the cotyledon cut away, bringing t o view the plumule concealed within. 53. A cross-section through the plumule, more magnified. FIG.' 51 Section of seed of Iris, enlarged, showing the small and apparently simple embryo at the base of the albumen 55 Germinating seed and seedling of the same, of natural size. OF THE EMBRYO A!ND SEEDLLNG. 25 carries up the light seed far above the surface of the ground, the tip only remaining in the albumen of the seed until that is ex- hausted, when the tip perishes and the emptied husk falls away. About this time the plumule shoots forth from one side of the subterranean base of this cotyledonar leaf, in the form of a second and similar filiform leaf, to be followed by a third, and so on. The sheathing bases of these succeeding leaves become the coats of the Onion-bulb. The internodes remain undeveloped until the plant is ready to blossom. Very similar is the germination of a date-seed, except that the protruding cotyledon does not lengthen so much, nor does it elevate the heavy seed. Instead of the seed being carried up, the lower end of the embiyo, contain- ing the plumule, is pushed down more or less into the loose soil, from which in time the developing plumule emerges. 41. The embryo of Grasses, especially of those which yield the cereal grains, is more complex, owing mainly to the great de- velopment of the plumule and the manner in which its rudimentary successively enclose each other. That of Maize or Indian Corn, one of the largest, is most convenient for study. (Fig. 56-59.) The floury part of the seed, which makes most of its bulk, is the albumen, largely composed of starch. The embryo is exterior to this, applied to one of its flat sides, and reaching from the thinner edge to or above the middle in the common variety of corn here represented. The form of the embiyo is best shown, detached entire, in Fig. 58 : its structure appears in the sections. The outer part is the cotyledon, which incompletely enwraps the plumule : it adheres closely to the albumen b}' the whole back, and remains un- changed in germination : its function is to absorb nutritive FIG. 56. Section, flatwise, of a grain of Indian Corn, dividing the albumen and the embryo. 57. Similar soction at right angles to the first. 58. A detached embryo: corresponding parts of Fig. 57 and 58 indicated by dotted lines. FIG. 59. Vertical section of Indian Corn across the thickness of the grain, dividing the embryo through the centre and displaying its parts: c, cotyledon; p, plumule; r, the radicle or caulicle. FIG. 60. Similar section of grain of rice. 61. Same of an oat-grain; the parts as in Fig. 59. 26 MORPHOLOGY matter furnished by the albumen, and to transmit it to the growing plumule. The plumule consists of a succession of rudimentary leaves, sheathing and enclosing one another, on the summit of a very short axis, which is mainry the caulicle, otherwise called rad- icle. This is completely en- closed b}' a basal portion of the cotyledon and of the outermost leaf of the plu- mule, which form a peculiar sheath for it, named the Coleorhiza* i. e. root-sheath : consequently the first root or roots have to break through this covering. As in the Oak and Pea (32), the very first or outermost leaves of the plu- mule develop imperfectly and not into efficient foliage. The one in Fig. 62, which encloses the rest in the early growth, is left behind as a mere sheath to the base of the following and more perfect leaves : it is the same as the lowest in Fig. 63. The leaves are first developed : the internodes lengthen later, and the lowest lengthen very little. Not rarely the first root starts singly from the tip of the caulicle (Fig. 62, just as in Fig. 55) ; but others of equal strength follow from any part of the caulicle, and soon from the nodes above ; and no tap-root is ever formed. 42. A Pseudo-monocotyledonous embryo occasionally occurs ; that is, one of the dicotyledonous t}'pe, of which one cotyledon is wanting through abortion. This occurs in Abronia, a genus related to Mirabilis, and bearing an embiyo very similar to that represented in Fig. 17, 18, except that one cot}'ledon is absent. The anomaly of an acotyledonous embryo occurs in Dodder, a plant of the dicotyledonous type, but with both cotyledons 1 This, the Cokorhize of Mirbel, should not be confounded (as by some it has been) with the "root-cap," or tissue which ordinary roots (whether primary or secondary) break through in their development or carry on their apex. FIG. 62. Early germination of Indian Corn. 63. More advanced germination ot same : roots produced from portion of stem above the cotyledon as well as below. OF THE ORGANS OF VEGETATION. 27 actually wanting, a correlation with its parasitic mode of life. (64, Fig. 78.) 43. The dicotyledonous and the monocotyledonous character of the embryo is correlated with profound differences in the whole ulterior development, as revealed in the structure of the stem, leaves, and flower ; which differences mark the two great divisions of Phasnogamous plants, viz. DICOTYLEDONES or DICOTYLEDONOUS PLANTS, and MONOCOTYLEDONES or MONOCOTYLEDONOUS PLANTS, names introduced into classification by Ray, and adopted by A. L. Jussieu, in his Genera Plantarum. CHAPTER III. MORPHOLOGY AND STRUCTURE OF THE ORGANS OF THE PLANT IN VEGETATION. SECTION I. OF THE ROOT. 44. The Root, which has been called the descending axis, is that portion of the body of the plant which grows downward, ordinarily fixing the vegetable to the soil, and absorbing from it materials which the plant ma}- elaborate into nourishment. As already stated (24), the root grows in length by continuous additions of new fabric to its lower extremit}', elongating from that part only or chiefly ; so that the tip of a growing root always consists of the most newly formed and active tissue. It normally begins, in germination, at the root-end of the caulicle, or so called radicle. But roots soon proceed, or may proceed, from other parts of the stem, when this is favorably situated for their production. The root does not grow from its naked apex, but from a stratum immediately behind it : consequently its blunt or obtusely conical advancing tip consists of older, firmer, and in part effete tissue. The tip of all secondary roots and rootlets FIG. 64. Magnified tip of root of a seedling Maple (such as in Fig. 9), sufficiency enlarged to indicate the cellular structure: a. the portion where growth is taking place; b the older and firmer tip. MORPHOLOGY OF THE ROOT. is similarly capped or protected. 1 But the so-called root-cap is seldom so distinct or separable as to deserve a particular name. 45. Nature of Growth, Cells. The development and growth of the root, as of other organs, results from the development, growth, and increase in number of certain minute parts, of which the plant is built up. These component parts are so much alike, at least in an earl} 7 stage, and are so obviously formed all on one type, that they take one common name, that of CELLS. These are the histological elements of plants, i. e. the units of minute anatomical structure. While, in the morphology of the, plant's obvious organs, analysis brings us to the phytomer (16) as the individual element which by a kind of propagation produces its like in a second phytomer, remaining however in connection with the first, thus building up the general structure, so, in an analogous wa}', each of the obvious parts each stalk or blade or rootlet is microscopically determined to be com- posed of these ultimate organic units, generally called cells. The cell (cellula, by the French conveniently termed cellule) is the living vegetable unit, in the same sense that the brick is the unit of a brick edifice. To make this analogy fairly complete, the bricks should be imagined to have a firm exterior or shell, and a soft or at length hollow - interior, also to be living when incorporated into the structure, and finally to be produced in the forming structure by a kind of propagation. The production or increase in number of these cells by development from previous ones, and their successive increase in size up to maturit}', arc what constitutes vegetable growth. 12 The inspection through a 1 The notion that the tip of the root consists of delicate forming or newly formed tissue, or bears some organ or structure of this nature (a " Spongiole"), has hardly yet been eliminated from the text-books and popular writings. It had no proper foundation in fact. In Lc.mna, and in some other aquatics, and also in some aerial roots, this older tissue often separates into a real root-cap, free at base, like an inverted calyptra. 2 This, as to the structure, is the subject of Ilistohjy ; as to processes or actions, the subject of Physiology; both to be treated in a separate volume. FIG. 65, 66. Portions of surface of Fig. 64, more magnified, clearly displaying the superficial cellular structure and the long processes from some of the cells, called root- hairs, which abound on the upper part of Fig. 64. MORPHOLOGY OF THE ROOT. 29 simple microscope of a slender young root, and of thin slices of it immersed in water, ma}' serve to give a general though crude idea of the vegetable cellular structure, sufficient for the present purpose. Roots are naked ; that is, the}' bear no other organs. When they send off branches, these originate from the main root just as roots originate from the stem ; and in both cases without much predetermined order. The ultimate and very slender branches are sometimes called root-fibrils ; but these are only delicate ramifications of the root. Like any other part of the plant, however, roots ma}' produce hairs or such like growths from the surface, which are wholly distinct from branches. (383.) 46. Root-hairs. Roots absorb water, &c., from the soil by imbibition through the surface ; that is, through the walls of the cells, which are in a certain sense permeable to fluids, more readily when young and tender, less so when older and firmer. Roots, therefore, absorb most by their fresh tips and adjacent parts ; and these are continually renewed in growth and extended fur- ther into the soil. As the active surface of a plant above ground is enormously increased by the spread of foliage, so in a less degree is the absorbing surface of young roots increased by the production of root-hairs. (Fig. 64, upper part, and more magni- fied in Fig. 65, 66.) These are attenuated outgrowths of some part of the superficial cells into capillary tubes (only one from each cell) , closed at the tip, but the calibre at base continuous with the cavity of the cell ; into which, therefore, whatever is imbibed through the thin wall may freely pass. These appear (as Fig. 64 shows) at a certain distance behind the root-tip. Further back the older or effete root-hairs die away as the cells which bear them thicken into a firmer epidermis. 47. To the general statement that roots give birth to no other organs, there is this abnormal, but b}' no means unusual excep- tion, that of producing buds, and therefore of sending up leaf}' branches. Although not naturally furnished with buds in the manner of the stem, yet many roots have the power of originat- ing them under certain circumstances, and some produce them habitually. Thus Apple-trees and Poplars send up shoots from the ground, especially when the superficial roots arc wounded. And the roots of Madura or Osage Orange so readily originate buds that the tree is commonly propagated by root-cuttings. 48. Kinds of Roots. The root, commonly single, which origi- nates from the embryo itself, is called the PRIMARY ROOT. (37.) Roots which originate from other and later parts of the stem, or elsewhere, are distinguished as SECONDARY ROOTS. But the eO MORPHOLOGY OF THE ROOT. latter are as normal as the primary root ; that is, to stems so situated that the}' can produce them. Most creeping plants emit them freely, usually from the nodes ; and so do most branches, not too old, when bent to the ground and covered with earth, thus securing the requisite moisture and darkness. Separate pieces of young stems (cuttings) can commonly be made to strike root. Upon this faculty of stems to originate roots depends all propagation by division, Ivy laying or layering, by cuttings, &c. It is mainly annuals and common trees that naturally depend on the primaiy root ; and most of these can be made to produce secondary roots. Even leaves and leaf-stalks of some plants may be made to strike root and be used as cuttings. (77.) 49. Duration. By differences in respect to this, cither the root or the plant, as the case may be, is distinguished into Annual, Biennial, or Perennial, according to whether life is contin- ued for a single year or season, for two, or for a greater number. The difference is not in all cases absolute or even well marked. 50. Annuals are plants which, springing from the seed, flower and seed the same year or season, and die at or before its close. They produce fibrous roots, either directly from the embryo and succeeding joints of stem (as in Grasses, Fig. 63), or from a persistent primary or tap-root, more or less thickened into a trunk or divided into branches. The products of vegetation in all such herbs are not stored in subterranean or other reservoirs, but arc expended directly in new vegetative growth, in the production of blossom, and finally in the maturation of fruit and seed. This completed, the exhausted and not at all replenished indi- vidual perishes. 51. But some annuals may have their existence prolonged by not allowing them to blossom or seed. Others, with prostrate stem or branches, may from these produce secondary roots, which, forming new connections with the soil, enable the newer growth to survive when the older parts with the original root have perished. And man}' herbs, naturally annuals, are continued from year to year through such propagation from the branches, used as layers or cuttings. Moreover, certain plants (such as Ricinus or Castor-oil Plant) , which arc perennial or even arbo- rescent in warm climates to which they belong, become annuals in temperate climates, early perishing by autumnal cold. 52. The annuals of cool climates, where growth completely ceases in winter, germinate in spring, mature, and die in or before autumn. But, in climates with comparatively warm and rainy winter and rainless summer, many germinate in autumn, vegetate MORPHOLOGY OF THE BOOT. 31 through the winter, flower and seed in spring, and perish in early summer. These may be termed WINTER ANNUALS. 53. Biennials are plants which, springing from the seed and vegetating in one season, live through the interruption of winter, and blossom, fructify, and perish in the next growing season ; their life being thus divided into two stages, the first of vegeta- tion, the second of fructification. In typical biennials, nearly the whole work of vegetation is accomplished in the first stage, with the result of accumulation of a stock of nutritive matter, to be expended in the second stage in the production of blossom and seed. This accumulation is usually stored in the root or in the base of a ver}^ short stem in c :>nnection with the root. The root of a biennial accordingly enlarges and becomes fleshy, or obese, as this matter accumulates. At the close of the growing season, the leaves perishing and the stem having remained very short (with undeveloped intsrnodes) , the root, crowned with the bud or buds, contains the main result of the summer's work, as provision for the next year's devel- opment and the completion of the C}*cle. This development, being thus amply provided for, is undertaken in spring with great vigor ; blossom, fruit, and seed are rapidl}' produced ; and the stock being consumed, but not at all replenished, the cells of the great root are now empty and effete, and the individual perishes. The Beet, Turnip, Parsnip, and Carrot arc fa- miliar examples of biennials, with the store of nourishment in the root. 1 The Kohl-rabi is a biennial with this deposit in the stem : the Cabbage, partly in the stem, partly in the head of leaves. 1 In these the caulicle enlarges with the root, so that the upper and bud-bearing end is stem. Tap-roots of this kind are said, in descriptive botany, to be Fusiform or Spindle-shaped, when broader in the middle and tapering towards both ends, as in the common Radish (Fig. 67); Conical, when tapering regularly from base to tip, as in carrots, &c. ; Napiform, i. e. Tiir)iij)-shaped,\\'\-\en the thickened part is wider than high, &c. Fascicled Roots are those which form in clusters ; these may be slender or . thickened. When much thickened, either irregularly or not of the above shapes, they are said to be tuberous. FIG. G7. Radish : a fusiform tap-root. MORPHOLOGY OF THE ROOT. 54. But some plants, such as the Radish, which when they spring from seed in autumn are true biennials, will when raised in spring pass on directly to the flowering stage in summer, or when sown after the warm season begins will often run through their course as annuals. Then there are various biennials which thicken the root very little and hold their leaves through the winter. Between these and winter annuals no clear demarcation can be drawn. As respects annual and biennial duration, the terms may for the most part be applied indiscriminately to the plant or to the root. We may say either that the plant is a biennial, or that its root is biennial. 55. Perennials are plants which live and blossom or fructify year after year. They may or they may not have perennial roots. In trees and shrubs, also in herbs with growth from year to } r ear from a strong tap-root, the root is naturally perennial. But in most perennials with only fibrous roots, these are produced anew from time to time or from year to year. Also, while some such roots remain fibrous and serve only for absorption, others ma3 T thicken in the manner of the ordinary biennial root and serve a similar use, i. e. become reservoirs of elaborated nourishment. The Dahlia (Fig. 68) and the Peony afford good examples of this. Sweet potato is another instance. 1 Most such roots have only a biennial duration : they are produced in one growing season ; they yield their store to form or aid the growth of the next. When perennials store up nutritive matter underground, the deposit is more commonly made in a subterranean portion of the stem, in tubers, corms, bulbs, &c. (See 115-122.) 56. The distinction between annuals and biennials is at times so difficult, and the particular in which the} T agree so manifest, namely, that of blossoming only once, then dying, as it were by exhaustion, that it was proposed by DeCandolle to unite 1 It is only by the readiness of this root to produce adventitious buds, especially from its upper part, that it has been mistaken for a tuber, such as the common potato. FIG. 68. Fascicled and tuberous or fusiform (secondary) roots of Dahlia: a, a. buds on base of the stem. MORPHOLOGY OF THE ROOT. 33 the two under the common appellation of MONOCARPIC plants, Plantte monocarpicce , taken in the sense of only once-fruiting plants ; and to designate perennials by the corresponding term of POLYCARPIC, Plantce poly earpiece, literally many-fruited, taken in the sense of many-times fruiting. 1 57. But the distinction even here is no more absolute than that between annuals and biennials. For example, it is not quite clear whether the Cardinal Flower and related species of Lobelia should be ranked as annuals, biennials, or perennials. The plants may blossom and seed toward the end of the season in which they came from seed ; or, germinated in autumn, the small seedlings may survive the winter ; but whenever fructified the fibrous-rooted mother plant dies throughout ; yet usually not before it has established, and perhaps detached from the base, small offsets to blossom the next season ; and so on. Then Houseleeks (Sempervivum) and such-like fibrous-rooted succu- lent plants multiply freely by offsets which are truly perennial in the sense that they live and grow for a few or several years ; but when at length a flowering stem is sent up producing blos- som and seed, that plant dies as completely and in the same manner as any biennial, only the generation of offsets surviving. The same is true of the Century plant (Agave Americana, wrongly denominated American Aloe) , which vegetates in the manner of the accumulating stage of a biennial, except that this continues for several or very many years, while the flower- ing stage, when it arrives, is precipitated and terminated in a single season. 58. Although the stem usually sends forth roots only when covered by or resting on the soil, which affords congenial dark- ness and moisture, yet these are in some cases produced in the open air. Roots may likewise subserve other and more special uses than the absorption of crude or the storing of elaborated nourishment. 59. Aerial Roots is a general name for those which are pro- duced in the open air. One class of these may serve the office of ordinary roots, by descending to the ground and becoming established in the soil. This occurs, on a small scale, in the stems of Indian Corn ; the lower nodes emitting roots which grow to the length of several inches before they reach the ground 1 These terms or some equivalents have a convenience in descriptive botany. But those employed by DeCandolle are not happily chosen, as has often been said. Montftocons (bearing progeny once) and Polytocoiis (bearing many times) would be more appropriate. 3 34 MORPHOLOGY OF THE KOOT. into which the}* penetrate. More remarkable cases abound in those tropical regions where the sultry air, saturated with moist- ure for a large part of the year, favors the utmost luxuriance of vegetation. In the Palm-like Fandanus or Screw-Pine l (Fig. 69), very strong roots, emitted in the open air from the trunk, and soon reaching the soil, give the appearance of a tree partially raised out of the ground. The famous Banyan -tree of India (Fig. 71) is a still more striking illustration ; for the aerial roots strike from the horizontal branches of the tree, often at a great height, at first swing- ing free in the air, but finally reach- ing and establishing themselves in the ground, where the}^ increase in diameter and form accessory trunks, surrounding the original bole and supporting the wide-spread canopy of branches and foliage. Veiy similar is the economy of the Man- grove (Fig. 70), which forms impenetrable thickets on low and muddy sea-shores in the tropics throughout most parts of the world, extending even to the coast of Florida and Louisiana. Here aerial roots spring not only from the main trunk, as in the Pandanus, but also from the branchlets, as in the Banyan. Even the radicle of the embryo starts into growth, protrudes, and attains considerable length while the fruit is still attached to the branch. 59. Aerial Rootlets for climbing are familiar in the Ivy of the Old World (Heclera), Trumpet-Creeper (Tecoma radicans) , and our Poison Ivy (Rhus Toxicodendron) ; by the adhesion of 1 So named, not from any resemblance to a Pine-tree, but from a like- ness of the foliage to that of a Pine-Apple. FIG. 69. Pandanus, or Screw- Pine; and in the background, 70, a Mangrove-tree (Rhizophora Mangle). MORPHOLOGY OF THE KOOT. 3b which the stems, as they grow, ascend walls and the trunks of trees with facilit}'. In Rhus a superabundance of these rootlets is produced, thickly covering all sides of the stem. 60. Epiphytes or Air-Plants also have roots which are through- out life unconnected with the ground. Epiphytes, or Epiphytic plants, as the name denotes, are such as grow upon other plants without taking nourishment from them. Deriving this from the air alone, the} r are called Air-plants. This name might be extended to the same or other kinds of plants attaching them- selves to bare walls, rocks, and the like, and unconnected with the soil, though such would not technically be epiphytes. Very many Lichens, Mosses, and other plants of the lower grade, and not a few phsenogamous plants, are in this case. The greater part of the pliomogamous Epiphytes pertain to two monocotyle- donous orders, the Orchis famil}' and that to which the Pinc- Apple belongs, viz. the Bromeliaceae. Their thread-like or cord-like simple roots cither adhere to the bark of the supporting tree, securing the plant in its position, or some hang loose in the air. Of these, Orchids, i. e. plants of the Orchis family, are the most show}' and numerous, and of the greatest variety of forms, especially of their blossoms, which are often bizarre and fantas- tic. They belong, naturally, to climates which are both warm and humid ; they arc highly prized in hot-house cultivation ; and, along with the hardy and terrestrial portion of the order, they are peculiarly interesting to the botanist on account of the singular and exquisite adaptation of their flowers in relation to insects which visit them. In some the blossoms curiously FIG. 71. The Banyan-tree, or Indian Fig (Ficus Imllca), 36 MORPHOLOGY OF THE BOOT. resemble butterflies or other insects ; as, for example, Oncidium Papilio, Fig. 72. Epiphytic orchids are indigenous to the United States only from Georgia to Texas, and only in humble forms, in company with species of Tillandsia, representing Bromeliace- ous epiphytes. The commonest of the latter tribe, and of most northern range, is the T. usneoides, the so-called Long Moss, which, pendent in long and tangled gray clusters or festoons from the branches of the Live-Oak or Long-leaved Pine, gives such a peculiar and sombre aspect to the forests of the warmer portions of our Southern States. 61. Parasitic Plants have the peculiarity that their roots, or what answer to roots, not only fix themselves to other plants, but draw therefrom their nourishment, at least in part. Among ciyptogamous plants very many Fungi are parasitic upon or within living plants or animals. But onlj' phaenogamous para- sites are here under consideration. These ma} r be divided into two classes ; those with and those without green foliage. 62. Green Parasites may be either wholly or partially parasitic ; that is, they may draw all their support from a foster plant, or FIG. 72. Oncidium Papilio, and, 73. Comparettia rosea; two showy epiphytes of the Orchis family; showing the mo