UNIVERSITY OF CALIFORNIA 
 AT LOS ANGELES
 
 MKMOIRS 
 
 OB* THE 
 
 TORREY BOTANICAL CLUB. 
 
 VOL. III. No. 2. 
 
 THE NAI ADAGES 
 
 NORTH AMERICA. 
 
 BY THOMAS MORONG. 
 
 (PLATES XX-LXXIV.) 
 
 ISSUED MARCH 15, 1893. 
 
 PRICE, - --- $2.00.
 
 
 
 MEMOIRS 
 
 
 OF THE 
 
 TORREY BOTANICAL CLUB. 
 
 No. 2. 
 
 The Naiadacese of North America, 
 
 BY THOMAS MORONG. 
 
 (PLATES XX. LXXIV.) 
 
 The first botanist to reduce the North American species of 
 Potauwgcton to anything like a complete and intelligible sys- 
 tematic shape was Dr. J. \V. Robbins, of Uxbridge, Mass. To 
 his pen is due the description in Gray's Manual, edition 5, of the 
 species within the range of that work. To this he added in the 
 Botany of King's Expedition an account of the species found in 
 Nevada, Utah and the adjoining regions, completing his work in 
 the Botany of California by Brewer and Watson by a determina- 
 tion of the species on the Pacific coast which were then known. 
 At his death, in 1875, Dr. Robbins bequeathed to me his collec- 
 tions, containing not only the gatherings of many years by his 
 own hand, but also specimens from the Herbarium of Tuckerman, 
 one of the earliest students of this genus, and from Oakes, his 
 close friend and collaborator, in whose lamented early death our 
 country lost one of its most promising naturalists. Dr. Robbins 
 left with his Herbarium an injunction that his plants should be dis- 
 tributed as widely as possible. I feel, therefore, that I am execu- 
 ting a sacred trust in issuing a monograph upon the Order that 
 includes as its principal part the family upon which my friend ex- 
 pended so much thought. Besides this, the paper here presented 
 includes not only the embodiment of my friend's most cherished 
 convictions, but the results of my own studies in a personal ex- 
 ploration of nearly all the waters from Quebec to Virginia, and 
 from the Atlantic to the Mississippi. This monograph, however, 
 
 271983
 
 would have been impossible, at least in its present form, except 
 for the assistance of friendly European botanists to whom I am 
 indebted for large suites of specimens and invaluable counsel. 
 With Mr. Arthur Bennett, of Croydon, England, distinguished for 
 his extensive acquaintance with Potamogcton forms in all parts of 
 the world, and for his contributions to the literature of the subject, 
 I have enjoyed a correspondence covering the last twelve years, 
 and during the course of that time have received from him speci- 
 mens of Naias,Zanic1iellia, Ruppia, Zostera and Potamogcton, which 
 represent nearly all the species of these families known to Euro- 
 pean Herbaria. His generous assistance has not ended here, but 
 he has examined for me the materials at Kew, the London Mu- 
 seum of Natural History, Berlin and the Herbarium of Linnaeus, 
 so that I feel as well acquainted with these great collections as if 
 I had visited them in person. I am also much beholden to that 
 acute botanist of Cambridgeshire, England, Mr. Alfred Fryer, for 
 beautiful specimens of the various interesting forms of Potamo- 
 geton which occur in the fens about Chatteris, and for many 
 original and discriminating analyses. Elegant specimens of the 
 Northern Scandinavian forms have been contributed by Dr. Gustaf 
 Tiselius, of Stockholm, than whom no one is a better judge of the 
 Continental species of Potamogeton. The late Prof. Caspary, of 
 Konigsburg, Prussia, was another of my European correspon- 
 dents, from whom was received many valuable specimens. The 
 collections of the Harvard Herbarium, of Columbia College, the 
 Academy of Sciences at Philadelphia, and at the National Her- 
 barium at Washington have been freely submitted for examina- 
 tion, as well as the large private collections of Mr. Canby, of 
 Wilmington, Delaware, I. C. Martindale, of Camden, New Jersey, 
 and others. Indeed, I may say that there is scarcely a collector of 
 pond weeds in the country with whom I have not at one time or 
 other held correspondence, and from whom I have not received 
 specimens. And yet, notwithstanding these advantages for a wide 
 comparison and a close study of this group of plants, so protean 
 are their forms, so eccentric their action, constantly changing 
 under changed conditions of season and water, that I put forth 
 this treatise with great diffidence, and feel that the subject is very 
 far from being exhausted
 
 3 
 
 The Naiadaceae arc for the most part strictly aquatic plants, 
 arising from long, sometimes nodose, rhizomes. Two of the 
 genera now included in the order, Triglochin and ScIicucJizcria, 
 are inhabitants of bogs and marshes; while another, Lilcea, usu- 
 ally begins its life under water, but continues to grow in the mud 
 after its native water has subsided. Triglochin and Lilcea bear 
 their inflorescence on scapes, the remainder on branching and 
 leafy stems. The aquatics are normally submerged plants, but 
 some of the Potamogeton family bear two kinds of leaves, floating 
 and submerged. The leaves are properly sheathing at the base, 
 and this appears in all the genera, except in some species of Pota- 
 mogcton. Even these, however, as in the group of which P. pec- 
 t in a fits may be considered as the type, the so-called stipule is adnate 
 to the base of the leaf and forms with it a sheath, produced at its 
 extremity into a sort of ligule. In the other species this organ, 
 though, for want of a better name, it is termed a stipule, is much 
 more in the nature of a spathe that at first encloses the young 
 buds, remaining afterwards at the base of the elongated nodes, 
 petioles and peduncles as an appendage which soon decays. In 
 Zostcra and PJiyllospadix the spathaceous character is still more 
 developed as the flowers are borne on true spadices contained in 
 a foliaceous sheath or spathe. Flowers perfect, monoecious or 
 dioecious, either naked, tubular, or with a perianth of 4 to 6 dis- 
 tinct herbaceous segments. Stamens I to 6, occasionally more, 
 distinct and hypogynous in the perfect flowers, solitary or connate 
 in the unisexual, with extrorse i-2-celled anthers. Ovaries I 
 to 6, distinct or rarely connate, I -celled; containing in our 
 North American species, with few exceptions, a single ovule. 
 Fruit, various; capsular, follicular or drupaceous. The fruit in the 
 Zostcrc(e is usually termed an utricle, but, while having a mem- 
 branaceous pericarp, it is frequently, at least, if not always, dehis- 
 cent. Seed straight or curved; the embryo corresponding, ortho- 
 tropous, anatropous or campylotropous, without albumen. 
 
 From this brief characterization it will be seen that the order is 
 composed of several heterogeneous groups. With the exception 
 of the Juncagineae and Lilaeae the order is a natural one. These 
 two groups have long hovered between Alismaceae, Aroideae and 
 Naiadaceae, with all of which they are more or less closely allied,
 
 and yet they are really distinct from either, and a rigid classifica- 
 tion would certainly follow the arrangement of Micheli in D. C. 
 Mon. Phan., and constitute each of them a separate order. Lilcea 
 is anomalous, and quite as distinct from the Juncagineae as the 
 latter are from Naiadaceae. There is an advantage, however, in 
 placing closely allied groups under one order, if possible, and I 
 therefore follow essentially the arrangement of Bentham and 
 Hooker. 
 
 Sub-order I. JUHCAGINCJE. 
 
 Marsh plants with rush-like leaves. Flowers spicate or race- 
 mose, perfect. Perianth 4-6-parted; segments in two series. 
 Stamens 3-6. Carpels 3 or 6, i-2-ovuled, more or less united 
 while immature, dehiscent or indehiscent. Seeds anatropous, em- 
 bryo straight. 
 
 1. TRIGLOCHIN. 
 
 Flowers ebracteate, racemose. Perianth segments 3 or 6. 
 Carpels 3 or 6, united until maturity. Leaves all radical. 
 
 2. SCHEUCHZERIA. 
 
 Flowers bracteate, racemose. Perianth segments 6. Stamens 
 6. Carpels 3, distinct, stem leafy, rush-like; fruit a follicle. 
 
 Sub-order II. I.II.AI-M:. 
 
 Marsh plants with cylindrical leaves. Flowers dimorphous, 
 solitary and in spikes, monoecious. Perianth none or a single 
 bract. Stamen I, ovary I, ovule I, anatropous. Carpels indehis- 
 cent. 
 
 3. LILAEA. Flowers monoecious, the pistillate naked at the 
 base of the leaves, with very long styles, or in close spikes on 
 scapes; the staminate in close spikes, on scapes, under a single 
 bract. Carpel I, I -seeded. 
 
 Sub-order III. x A I Vl>i:.i,. 
 
 Immersed aquatics with flat leaves. Flowers variously ar- 
 ranged, perfect, monoecious or dioecious. Perianth of 4 segments, 
 or a mere hyaline envelope. Ovaries solitary or distinct, i-ovuled. 
 Carpels rarely dehiscent. Embryo curved or straight. 
 
 Potameae. 
 
 Flowers spicate, perfect, bractless. Perianth of 4 segments or 
 none. Stamens 4 or 2. Carpels separate, I -seeded; seeds cam- 
 pylotropous. Embryo curved.
 
 4- POTAMOGETON. 
 
 Perianth segments 4. Carpels sessile. 
 
 5. RUPPIA. 
 
 Perianth none. Carpels long-stipitate. Fruit in umbels. 
 
 Zannichelliae. 
 
 Flowers axillary. Perianth none or hyaline. Stamen I with 
 elongated filament, or of 2 or 3 connate, sessile anthers. Ovaries 
 2-9, i-ovuled; ovules pendulous from the top of the cell, ortho- 
 tropous. 
 
 6. /AXXICHELLIA. 
 
 Perianth none. Stamen I , with a short filament. Carpels 2-9, 
 a little curved. Fruit in umbels. 
 
 Kaiae. 
 
 Flowers monoecious or dioecious, axillary. Perianth a hyaline 
 envelope. Stamens of I sessile or 2 connate anthers. Ovaries 
 solitary, i-ovuled; ovules anatropous. Embryo oblong. 
 
 7. \AIAS. 
 
 Flowers solitary or glomerate. 
 
 Zostereae. 
 
 Marine plants with long linear leaves. Flowers monoecious 
 or dioecious, on an enclosed spadix. Perianth none. Ovaries I, 
 sessile, i-ovuled; ovules pendulous, orthotropous. Embryo 
 straight. 
 
 8. ZOSTER A. 
 
 Flowers monoecious. Carpels ovoid. 
 
 9. PHVLLOSPAIMX. 
 
 Flowers dioecious. Carpels heart-shaped. 
 
 i. TRIGLOCHIN, L. Sp. PI. 338 (1753). 
 Marsh plants with radical, semiterete, fleshy leaves, which have 
 membranous, often ligulate, sheaths at the base. Flowers per- 
 fect, in spikes or racemes, on long, smooth, naked scapes. Seg- 
 ments of the perianth 3-6, concave, the 3 inner inserted higher 
 than the others. Stamens 3-6 ; anthers 2-celled, s.essile or nearly 
 so, inserted at the base of the segments and attached by the back, 
 extrorse and with the segments deciduous. Ovaries 6, united or
 
 rarely free, I -celled, sometimes partially or wholly abortive ; ovules 
 solitary, basilar, erect, anatropous ; style short or often wanting; 
 stigmas as many as the ovaries, plumose. Fruit of 3-6 cylindra- 
 ceous, oblong or obovoid carpels, which are distinct or connate, 
 coriaceous, costate, when ripe separating from the base upward from 
 a persistent central axis, the tips straight or recurved, dehiscing 
 by a ventral suture. Seeds erect, cylindraceous or ovoid-oblong, 
 compressed or angular. Embryo conformed to the seeds. 
 
 The carpels often appear indehiscent in the dried specimens, 
 but they are all furnished with a distinct internal carinated suture 
 which it may need moisture to open. The species have a rush- 
 like appearance, and are generally found upon saline marshes near 
 the seashore or inland, and often, also, in fresh water bogs and 
 marshes. The long, linear leaves are usually erect, sheathing each 
 other and the scape at the base, often partially buried in the earth. 
 
 Authors vary much as to the number of species, Kunth enu- 
 merating 1 6, which Micheli reduces to 9. They are widespread, 
 inhabiting the frigid and temperate zones of both hemispheres. 
 
 Three species only occur in North America. 
 
 Carpels 3. 
 
 Fruit linear or clavate, tapering to a subulate base. I. T. palustris, 
 
 Fruit globose. 2. T. striata. 
 
 Carpels 6. 
 
 Fruit oblong or ovate, obtuse at base. 3. T. maritima. 
 
 i. TRIGLOCHIN PALUSTRIS, L. Sp. PI. 338 (1753). 
 Perennial. Rhizome short, oblique, throwing out radical fibres 
 and slender, fugacious stolons. Leaves narrowly linear, shorter 
 than the scapes, 5-12 inches long, tapering to a sharp point; 
 ligule very short. Scapes 1-2 from the same rootstock, very 
 slender, striate, 8-20 inches high. Racemes 5-12 inches in length; 
 pedicels capillary, in fruit erect-appressed and 2^-3^ lines long. 
 Perianth segments 6, greenish-yellow, ovate or roundish, in 2 
 series, the inner a little higher. Anthers 6, sessile, in 2 series, 
 each under a perianth segment, large, yellow. Ovaries of 3 
 united carpels and as many cells and ovules ; stigmas as many as 
 the carpels, sessile, plumose. Fruit 3-3^ lines long, slender, 
 linear or clavate, tapering into a base scarcely thicker than the 
 pedicel and tipped with 3 short recurved points. Ripe carpels
 
 cylindrical, tapering at base into a sharp hair-like termination, 
 separating upwardly from the axis, and hanging suspended from 
 its apex ; central axis 3-winged. Seeds loose in the carpels, 
 straight, the raphe marked by a purple line. 
 
 This species is readily recognized by its very slender, erect 
 scapes, and its racemes of slender, erect, club-shaped and long cap- 
 illary pedicels. 
 
 It grows in boggy places or sometimes in slightly wet grounds, 
 or in moist sands by brooksides and brackish pools and ponds. 
 I found it quite abundant near the Niagara Falls on the Canada side. 
 It also occurs at various localities in Western New York, and thence 
 westward to Montana (Belt River Canyon, Williams) and north- 
 ward through Canada from New Brunswick to Alaska (Macoun). 
 Common in the British Islands and throughout Europe and 
 Northern Asia. (Plate XX, with a ripe fruit magnified.) 
 
 2. TRIGLOCHIX STRIATA, R. and P. Fl. Peruv. iii. 72 (1802). 
 
 T. triandra, MX. Fl. i. 208 (1803). 
 
 Small perennials from upright or oblique, stoloniferous root- 
 stocks. Scapes i or 2 from the same rhizome, more or less angu- 
 lar, usually not over 10 inches high, but sometimes reaching an al- 
 titude of 14 inches. Leaves slender, slightly fleshy, nearly or 
 quite as long as the scapes and ^-i line in width. Flowers very 
 small, light yellow or greenish, in spikes or racemes, with pedicels 
 only Y2~y\ line long, not increasing in fruit, the spikes 1-5 inches 
 in length. Perianth segments 3 ; stamens 3, oval, large. Ovaries 
 
 3, united, crowned with long plumose stigmas. Fruit globose, 
 y-\ line in diameter, appearing 3-winged when dry by the con- 
 traction of the carpels. Carpels 3, coriaceous, rounded and 3- 
 ribbed on the back. Central column broadly 3-winged, the 
 wings composed of a thin membrane with a strong rib-like border. 
 Seeds loose, slightly curved, the raphe inconspicuous. 
 
 Our species belong to the form called robustior by Micheli. 
 Two other smaller and more slender forms are described, named 
 JUifolia and hninilis, the former from the Pacific islands and the 
 latter from Chile. 
 
 7. striata seems to take the place of our other species in the 
 Southern States, occurring along the seaboard from Maryland to
 
 8 
 
 Louisiana in salt and fresh water marshes. A widely diffused 
 species, native not only of the United States, but also of Brazil, 
 Chile, many of the Pacific Islands and Southern Africa. (Plate 
 XXI, with a ripe fruit magnified.) 
 3. TRIGLOCHIN MARITIMA, L. Sp. PL 339 (1753). 
 
 T. Mexicana, H. B. K. Nov. Gen., i. 244 (1815). 
 
 T. data, Nutt. Gen. i. 237 (1818). 
 
 T. maritime* , var. data, A.. Gray, Man. Ed. 2, 437 (1852). 
 
 A perennial plant with a long, unstoloniferous, often sub- 
 ligneous, rootstock, and a thick caudex which is usually covered 
 with the sheaths of old leaves. Scapes stout, nearly terete, striate, 
 12 to 24 inches high, commonly solitary. Leaves much shorter 
 than the scapes, fleshy, semi-cylindrical, striate, tapering gradually 
 to a long acute or obtuse point. The leaves are usually about i 
 line broad, but sometimes, as in a specimen collected in California 
 by Dr. Bigelow, on Lieut. Whipple's expedition, reaching a width 
 of nearly 2*^ lines. Flowers very numerous, often densely crowded 
 on the scape, and even appearing verticillate at times. The ra- 
 cemes often reach a length of 40 cm. or more; pedicels decurrent, 
 i to i y 2 lines long, slightly increasing in fruit. Perianth seg- 
 ments, 6, the 3 interior smaller, ovate and greenish-white, each sub- 
 tending a large sessile anther. Ovaries 6, united, each i -celled 
 and i-ovuled; stigmas sessile, plumose. Fruit 2^ or 3 lines 
 long and i l / 2 to 2 lines thick, oblong or ovate, obtuse at the base, 
 with 6 recurved points at the apex. Carpels 6, 3-angled, flat or 
 slightly grooved on the back, or the dorsal edges curving upwards 
 and sharply winged (T. data, Nutt.), separating at maturity from 
 a hexagonal axis; seeds much smaller than the thick membranous 
 carpels, straight or slightly curved; raphe not conspicuous. 
 
 The distinctions between this species and the form data of 
 Nuttall, depending upon the presence or absence of wings on the 
 carpels, are too inconstant to warrant even the making of a variety. 
 T. maritima generally occurs on salt marshes, along the sea- 
 coast and on saline grounds in the interior of the country, but is 
 not uncommon in fresh marshes, It is widely spread on our con- 
 tinent from Labrador to New Jersey, and westward to Alaska 
 and California. From Southern Mexico to Terra del Fuego, and 
 in Hurope and Asia it is equally common. (Plate XXII.)
 
 2. SCHEUCHZERIA, L. Sp. PL 338 (1753). 
 
 Rush-like bog perennials with creeping rootstocks and erect, 
 leafy stems. Leaves semiterete below and plane above, striate, fur- 
 nished with a pore at the apex and a membranous, ligulate sheath 
 at the base. Flowers small, racemose. Perianth 6-parted, regu- 
 lar, biserial, persistent. Stamens 6, biserial, inserted at the base 
 of the segments; filaments elongated; anthers linear, basifixed, 
 extrorse. Ovaries 3, rarely 4-6, separate or connate at the base, 
 i -celled, each cell containing one or two collateral ovules. Stig- 
 mas sessile, papillose or slightly fimbriate. Carpels 3-6, shortly 
 connate at base, divergent, inflated, coriaceous, 1-2 seeded. Fruit 
 a follicle, thick, flattish-oval, dehiscing laterally, containing one 
 or two smooth seeds which have a clearly marked raphe and 
 a thick hard testa. Seeds exalbuminous, straight or slightly 
 curved, loose in the carpel. 
 
 Only one species is known. 
 
 i. SCHEUCHZERIA PALUSTRIS, L. Sp. PI. 338 (1753). 
 
 Leaves 4-16 inches long, the cauline diminishing to bracts 
 among the inflorescence. Stems one or more, rising from a long 
 creeping rootstock, and usually clothed at the base with the re- 
 mains of old leaves, 4-10 inches in height; sheaths on the radical 
 leaves often 4 inches in length, with a ligule nearly 5 lines long. 
 Pedicels 3-10 lines long, spreading in fruit. Flowers white, few, in 
 a lax raceme; perianth segments acute or obtuse, membranaceous, 
 I -nerved, \y 2 lines long, the inner ones narrower. Stamens 2^- 
 3 lines long. Follicles 3-4 lines in length, divergent, only slightly, 
 if at all united at the base. Seeds oval, fuscous, 2 l / 2 or 3 lines in 
 length, with a very hard testa. 
 
 This plant occurs rather rarely in deep quaking bogs, among 
 moss and grass, from New Brunswick to Hudson's Bay in Canada, 
 from New England to New Jersey, and westward to Washington 
 and California. It is also an inhabitant of Northern Europe and 
 Asia. (Plate XXIII. with a flower magnified.) 
 
 3. LILyEA, Humb. et Bonpl. PI. sEq. i. 221 (1808). 
 Annual stemless, paludose plants, with simple, slender scapes 
 and radical leaves which are slightly dilated at the base. Flowers 
 monoecious and dimorphous, the one sort solitary, fertile and dis-
 
 10 
 
 posed among the leaves at the base, with long, thread-like styles. 
 The other kind of flowers are monoecious, in dense spikes at the 
 apex of slender scapes. Staminate flowers imbricated in narrow, 
 oblong spikes ; stamen of a single, 2-celled anther nearly sessile, in 
 the axis of a white, linear, petaloid bract longer than itself. Fertile 
 flowers imbricated in larger, conical, crowded spikes, bractless, 
 consisting of a I -celled, i-ovuled ovary which is tipped with a 
 capitate stigma ; ovules anatropous. Fruit ovoid, costate, indehis- 
 cent, thick, membranaceous. Seeds oblong-conical, the raphe 
 filiform, inconspicuous; embryo thick, conical, with an elongated 
 cotyledon and short radicle. 
 
 Natives of western North America, Mexico and equatorial 
 South America. One species only is known. 
 
 i. LIL^EA SUBULATA, Humb. et Bonpl. PI. ^Eq. i. 222, tab. 63 (1808). 
 
 Hctcrostylus gra mineus, Hook. Fl. Bor. Am. ii. 171 (1840). 
 
 The leaves of this species are not, as described even by so 
 careful an observer as Micheli, "grass-like," but as Mr. S. B. 
 Parish, of San Bernardino, Cal., writes, cylindrical, about the size 
 of a goose quill and filled with spongy cellulose matter which 
 causes them to become flat under pressure, and hence very decep- 
 tive in herbarium specimens. They are numerous, 8 to 1 2 inches 
 high, erect, tapering to a point at the apex. Scapes 4 to 8 inches 
 high, much shorter than the leaves and like them terete. The 
 curious basilar flowers produce an enormously long filiform style, 
 nearly as long as the scapes, sometimes even 8 inches, and tipped 
 with a capitate stigma. They remind me very much of the similar 
 flowers and styles of Scirpus supinus var. Hallii which I once 
 found growing at Winter Pond, Winchester, Mass. Their fruit is 
 many-ribbed, about 3 lines in length. The flowers of the spikes 
 are smaller in size, those of the staminate flowers having abortive 
 fertile flowers mixed with them. Micheli quotes Hieronymus as 
 saying that the spikes are androgynous, having fertile flowers at 
 the base, perfect in the centre and sterile at the apex, but none of 
 our North American plants show this so far as I have seen, nor 
 does Bonpland, in his original description, seem to have noticed 
 such an arrangement. Ovaries in the upper flowers with a short, 
 thick style, crowned by a papillose stigma.
 
 11 
 
 In shallow water or mud. The plant was originally collected by 
 Humboldt and Bonpland near Bogota in the United States of 
 Colombia, but it has since been found in many other parts of 
 South America. The writer gathered it at Buenos Aires. It oc- 
 curs on Vancouver's Island (Macoun.), in San Bernardino county, 
 Cal. (Parish), and Chihuahua, Mexico (Pringle). (Plate XXIV.) 
 
 4. POTAMOGETON, L. Sp. PL 126 (1753). 
 
 Leaves alternate or the uppermost opposite, often of two kinds, 
 submerged and floating, the submerged linear and grass-like, the 
 floating coriaceous, lanceolate, elliptical, ovate or oval. Spathes 
 stipular, often ligulate, free or connate with the base of the leaf or 
 the petiole, enclosing the young buds and usually soon perishing 
 after expanding. Peduncles axillary, usually emersed. Flowers 
 small, spicate, greenish or rufescent. Perianth segments 4, shortly 
 unguiculate, concave, valvate in aestivation. Stamens of 4 sessile 
 anthers, inserted on the claws of the sepals. Ovaries 4, sessile, 
 distinct, i -celled, i-ovuled, attenuated into a short, erect or re- 
 curved style, or with a sessile stigma. Fruit of 4 ovoid or subglo- 
 bose drupelets, the pericarp usually thin and hard or spongy. 
 Seeds crustaceous, exalbuminous, campylotropous, with an unci- 
 nate embryo the radicular end of which is thickened. Very fre- 
 quently amphibious forms of many of the floating-leaved species 
 occur, which it is difficult to distinguish. These are dwarf, stocky 
 forms, generally without submerged leaves, nearly always without 
 fruit, and caused by the drying up of the water in which they 
 grow. About the only method of deciding the species in such 
 cases is by the occurrence of the normal form in the adjoining 
 waters, and by the coriaceous leaves and stipules which usually 
 retain their normal character. P. pulclicr, P. lonc/iitcs, P. lietcro- 
 pliyllus and P. spathulafonnis (in England) are greatly addicted 
 to this habit. 
 
 By nutlet in the following descriptions is meant the crustace- 
 ous seed freed from the pericarp. 
 
 About 65 fairly well-defined species occur in the cool waters of 
 the temperate zones in all the continents, and the great bulk of 
 them in northern North America, Europe and Asia. Of the 37 
 North American species, 14, so far as known, are confined to this 
 country.
 
 12 
 
 Stipules axillary and free from the leaf. 
 With floating and submerged leaves. 
 Submerged leaves bladeless. 
 
 Nutlets deeply pitted. I. P. n a tans. 
 
 Nutlets not pitted. 2. P. Oakesianus. 
 
 Submerged leaves with a proper blade. 
 
 Submerged leaves of 2 kinds, lanceolate and oval or oblong. 
 Uppermost broadly oval or elliptical, lowest lanceolate. 
 
 3. P. amplifolius. 
 Uppermost lanceolate and pellucid, lowest oblong and opaque. 
 
 4. P. pulcher. 
 Submerged leaves all alike, capillary or linear-sectaceous. 
 
 l-nerved or nerveless. 27. P. Vaseyi. 
 
 3-nerved. 28. P. lateralis. 
 
 Submerged leaves all alike, linear. 
 
 Nearly the same breadth throughout, obtusely pointed, coarsely cellular-retic- 
 ulated in the middle. 5. P. Nuttallii. 
 Broader at base, acute, without cellular-reticulation. 
 
 ^ IO. P. heterophyllus. 
 
 Submerged leaves all alike, lanceolate. 
 
 Fruit strongly embossed or dentate on the keels. 9. P. Mexicanus. 
 
 Keels of fruit even. 
 
 Uppermost leaves petioled, lowest sessile. 6. alpinus. 
 
 All petioled. 
 
 Floating leaves large, broadly elliptical, rounded or subcorclate at base. 
 
 12. P. Illinoensis. 
 Floating leaves narrowly elliptical, sloping at base. 
 
 7. P. lonchites. 
 Floating leaves mostly obovate or oblanceolate, sloping at base. 
 
 8. P. Faxoni. 
 All sessile or subsessile. 
 
 Fruit only I line long, obscurely 3 keeled. II. P. spathulvformis. 
 
 Fruit \y z lines long, distinctly 3-keeled. 13. P. angitstifolius. 
 
 With submerged leaves only. 
 
 Without propagating buds or glands. 
 
 Leaves with broad blades, mostly lanceolate or ovate, many nerved. 
 Leaves subsessile or shortly petioled, mostly acute or cuspidate. 
 
 14. P. hicens. 
 Leaves semi-amplexicaul, obtuse and cucullate at the apex. 
 
 15. P. prtelongus. 
 Loaves meeting around the stem, very obtuse at the apex, not cucullate. 
 
 1 6. P. perfoliatus. 
 Leaves with narrow blades, linear or oblong-linear, several nerved. 
 
 Leaves oblong-linear, 5-7 nerved, obtuse at the apex. 
 
 17. P. Mysticus.
 
 13 
 
 Leaves narrowly linear, 3-nerved, acute at the apex. 
 
 23. P, foliosits. 
 
 Leaves with narrow blades, capillary or setaceous, i-nerved or nerveless. 
 Peduncles terminal, very long. 1 8. P. confervoides. 
 
 Peduncles axillary, short. 19. P. Ctirtissii. 
 
 With propagating buds or glands, or both. 
 With buds but without glands. 
 
 I /eaves serrulate, 3 y-nerved. 20. P. crispus. 
 
 Leaves entire, with 3 principal and many fine nerves. 
 
 21. P. zosterafolius. 
 Commonly with glands, but no buds. 
 
 Stems long branching from the base, leaves lax, plane, 3-nerved, abruptly 
 acute or cuspidate. 22. P. Hillii. 
 
 Stems simple, leaves strict, revolute, 3-5-nervecl, acuminate. 
 
 26. P. rutilus. 
 With both buds and glands. 
 
 Glands large and translucent, buds rare. 24. P. obtusifolius. 
 
 Glands small, often dull, buds common. 
 
 Leaves linear, 5~7-nerved. 25. P. major. 
 
 Leaves linear, 3-nerved. 29. P. pusillus. 
 
 Leaves capillary, i-nerved or nerveless. 30. P. gemmiparus. 
 
 Stipules aclnate to the leaves or petioles. 
 With floating and submerged leaves. 
 
 Submerged peduncles as long as the spikes, clavate, often recurved. 
 
 31. P. diversifo Hits. 
 Submerged peduncles none, or at most hardly a line long. 
 
 32. P. Spirillus. 
 With submerged leaves only. 
 
 Stigma broad and sessile. 33. P.filiforviis. 
 
 Style apparent, stigma capitate'. 
 
 Fruit without keels or obscurely keeled. 
 
 Leaves capillary, i-nerved or nerveless. 34. P. pectinatus. 
 
 Leaves linear, 3~5-nerved. 35. P. latifolius. 
 
 Fruit strongly 3-keeled. 
 
 Leaves entire, 3~5-nerved. 36. P. ititerruptus. 
 
 Leaves minutely serrulate, finely many-nerved. 37. P. Robbinsii. 
 
 I. POTAMOGETON NATANS, L. Sp. PI. 126 (l7S3). 
 
 The stems of this species grow from two to four feet in height, 
 usually in still waters with a muddy bottom, and are simple or 
 sparingly branched. Floating leaves thick, coriaceous, the blade 
 ovate, oval or elliptical, 2-4 inches long and 1-2 inches broad, 
 usually tipped with a short, abrupt point, rounded or sub-cordate 
 at base, and with 20-30 rather strong nerves. The submerged 
 leaves by which this species can always be distinguished from 
 every other except P. Oakcsianus, are phyllodia, without the
 
 14 
 
 slightest sign of a lamina. I notice that they generally form a 
 coriaceous blade at their tips when they reach the surface, show- 
 ing that they are true petioles. Being attached to the lower part 
 of the stem, they often become extremely long. I have specimens 
 in which they are from 15 to 1 8 inches in length. Commonly 
 they perish early, and are seldom seen at the fruiting period. 
 Stipules long and acute (sometimes 4 inches), 2-keeled. Pedun- 
 cles equalling the stem in thickness, and from 2 to 4 inches in 
 length. Spikes cylindrical, sometimes upwards of 2 inches long, 
 densely flowered and fruited. Fruit turgid, 2-2^5 lines long 
 and about I ^ lines broad, scarcely keeled, narrowly obovate, 
 slightly curved on the face ; style short and facial ; nutlet hard, 
 more or less deeply pitted or impressed on the sides, with 2 grooves 
 on the back; embryo forming an incomplete circle, the apex 
 pointing towards the base. 
 
 The floating leaves of this species are occasionally very obtuse 
 or acute at the apex and sloping at the base. The Atlantic coast 
 forms generally have small coriaceous leaves, while those of Europe 
 and our interior states are large. Very rarely floating leaves oc- 
 cur with as many as 40 nerves. The stipules also are sometimes 
 obtuse and usually deciduous beneath the water. An extreme 
 form (var. prolixus, Koch.), growing in deep water and strong cur- 
 rents, has all the parts very slender and greatly elongated. I have 
 collected this with stems 12 feet in length, submerged leaves 21 
 inches long, and floating leaves lanceolate or lance-oblong and 
 very acute. 
 
 Common in ponds and streams throughout Canada and 
 the United States, extending into Mexico. Equally common 
 in Europe. Occurs also in Africa and Asia. Fruits in July and 
 August in our Northern States. (Plate XXV.) 
 
 2. POTAMOGETOX OAKESiANUS, Robbins, in A. Gray, Man. cd. 5. 
 
 485 (1867). 
 
 Stems very slender, often much branched from below. Float- 
 ing leaves elliptical, obtuse at the apex and rounded or slightly 
 sub-cordate at the base, 1-2 inches long and 5-9 lines wide, with 
 from 12 to 20 nerves and slender petioles 2-6 inches long. Sub- 
 merged leaves mere capillary phyllodia, often continuing through
 
 15 
 
 the flowering season. Peduncles 1-3 inches in length, commonly 
 much thicker than the stem, mostly solitary. Spikes cylindri- 
 cal, y^-i inch long, usually not fruiting freely. Stipules hardly 
 keeled, acute. Fruit obovate, about I */ lines long and I 
 line broad, nearly straight on the face, 3-keeled, middle keel 
 sharp; the style apical or often sub-apical; sides of the nutlet not 
 pitted, but sometimes slightly impressed; embryo circle incomplete, 
 the apex pointing towards the base. 
 
 This species may readily be distinguished from P. nafans, 
 which it resembles, by its much smaller parts, its almost uniformly 
 elliptical floating leaves, its delicate phyllodia, thickened peduncles, 
 tricarinate fruit, and even-sided nutlet. 
 
 My friend, Arthur Bennett (Jour. Bot. 1890, p. 301), regards 
 this species as the P. Nuttallii of Ch. and Sch. (Linnaea, ii. p. 226), 
 which would give that name the priority, having been published 
 in 1827. With this judgment I am unable to agree, since it ap- 
 pears to me that the fruit of P. Oakesianus does not correspond to 
 the description or the figures given in that work. It is there said 
 to be " oblique lenticulari-suborbicularis," but in shape it is 
 rarely otherwise than narrowly obovate. The sides of the nutlet 
 are said to be impressed in the middle, whereas in this species 
 they are even. Our plant fails especially to agree with the de- 
 scription and figure of these authors in the embryonic curve, their 
 seed being said to be " cochleato-convolutum, unico et paululum 
 quod supersit anfractu," but in this case the seed is not cochleate- 
 convolute, nor is the embryo coiled upon itself, the apex simply 
 pointing to the base. The figure of the embryo in Linnaea as 
 compared with the embryo of P. Oakesianus is quite conclusive. 
 The fruit figured by Cham, and Schlecht. seems to me to agree 
 so exactly with that of P. Claytonii, Tuck., that I have not hesitated 
 to adopt their name for that species, as will be seen below. 
 
 The name here used was given by Dr. Robbins in honor of 
 his old and intimate friend, William Oakes, of Ipswich, Mass. 
 
 A rather rare species, occurring in still waters, Anticosti, Canada, 
 (Macoun), N. H. to N. J. and westward to the Adirondacks, N. Y. 
 A doubtful form is sent from Nebraska by H. J. Webber. It is 
 exceedingly abundant in some of the small ponds of Nantucket, 
 where it fruits very freely. June-Aug. (Plate XXVI.)
 
 16 
 
 3. POTAMOGETON AMPLiFOLius, Tuckerman, Am. Jour. Sci. and 
 
 Arts, 2d ser. vi. 225 (1848). 
 
 Stems simple, 2-5 feet long, occasionally branching. Floating 
 leaves thick, oval or ovate, abruptly pointed at the apex and 
 rounded at the base, 2-4 inches long and I y-2 inches broad, 32-40 
 nerved, on petioles 3 to 5 inches in length. Submerged leaves 
 large, the uppermost often elliptical or oval, 3-6 inches long and 
 \-2.y 2 inches broad, having about the same number of nerves as 
 the floating and sometimes shining; the lowest lanceolate, acute 
 at each end, often as much as 8 inches long and 2 inches wide, 
 with about 25 nerves. The lowest leaves frequently have the two 
 sides of the blade closed and assume a recurved or falcate 
 shape. All the submerged leaves are thin and pellucid, and 
 are borne on short petioles. Stipules tapering to a long sharp 
 point, 2-keeled, closely embracing the stem or spreading with age, 
 sometimes 4 inches long. Peduncles thickening upwards, 2 to 8 
 inches long. Spikes thick, cylindrical, I to 2 inches long. Fruit, 
 2 to 2.y 2 lines in length by i^ lines in breadth, with a thick, hard 
 shell, turgid, obliquely obovate in shape, 3-keeled, the middle keel 
 prominent; sides not impressed, face more or less angled; style, 
 sub-apical; embryo slightly incurved. In the Western lakes and 
 ponds the plants with the large oval or ovate submerged leaves 
 are most common, and those with recurved leaves rare, while the 
 reverse is the case in Eastern waters. Aberrant forms occur with 
 petioles very slender and 10 or more inches in length. I have 
 also collected occasional specimens which have at the lowest part 
 of the stem small, opaque, oblong, long-petioled leaves similar to 
 those found on P. pulcher ; and, also, a very rare form which re- 
 sembles P. natans in its upper foliage and in fruit, except the em- 
 bryo. Canada from Ontario to Vancouver's Island (Macoun). 
 United States from New England to Kentucky, and westward to 
 Minnesota and Nebraska. An endemic species. July to Sept. 
 (Plate XXVII, showing below one of the curved submerged 
 leaves.) 
 
 4. POTAMOGETON PULCHER, Tuckerm. Am. Jour. Sci. and Arts, ist 
 
 ser. xlv. 38(1843). 
 
 Stems simple, terete, black-spotted, from I to 2 feet high. 
 Floating leaves usually massed at the top on short, lateral branches,
 
 17 
 
 alternate, ovate or roundish-ovate, sometimes large oval or nearly 
 orbicular, subcordate, 2-4^ inches long and 9 lines to 31^ inches 
 broad, 25-33-nerved. Petioles about as thick as the stem, 2-4 
 inches long, and spotted like that. Submerged leaves of 2 kinds, 
 the uppermost pellucid, lanceolate, long-acuminate, undulate, 3-8 
 inches in length, 6-18 lines in width, tapering at the base into a 
 short petiole, 10 to 20 nerved, irregularly cellular-reticulated for a 
 narrow space on each side of the midrib; the lowest near the base 
 of the stem, fewer, much thicker, opaque, spatulate, oblong or 
 ovate, with a rounded, tapering base, on petioles which are often 
 broadened and y 2 to 4 inches in length. The submerged leaves 
 are usually much decayed at the time of flower and fruit, and, in 
 order to get them in good condition, they must be gathered be- 
 fore the flowering period. Stipules obtuse or long-acuminate, bi- 
 carinate. Peduncles slightly thicker than the stems, 2 to 4 inches 
 long. Spikes about an inch in length and densely fruited, when 
 fruiting at all. Fruit tapering at top into a stout apical style, 2 
 lines or a little more in length and I ]/ 2 lines in breadth, thick and 
 turgid, the back sharply 3-keeled, middle keel prominent, largely 
 rounded at base; face angled near the centre, with a sinus below; 
 embryo coiled I y$ times. Aberrant forms with coriaceous sub- 
 merged leaves, and the floating ones with slender petioles, 10 or 
 more inches long, are found in mill ponds where the water has 
 been drained off and the pond refilled. It occurs sometimes, also, 
 in very deep water, when the upper part lengthens into slender 
 simple or long, branching stems, very different in appearance from 
 the shallow water forms. It may also be found quite often in 
 an amphibious state in pools which have become nearly dry, when 
 it is almost without stem and exhibits coriaceous leaves only. 
 
 An endemic species, rare, and still more rarely found in fruit. 
 The most abundant locality in which I have observed it is on the 
 island of Nantucket, where it nearly fills some of the small ponds, 
 and fruits quite freely. 
 
 Ponds, in Wells, Me. (Harvey), Brattleboro, Vt. (Frost), East- 
 ern Massachusetts to Pennsylvania, Georgia, and near St. Louis, 
 Mo. (Engelmann). June, July (Plate XXVIII).
 
 18 
 
 5. POTAMOGETON NuxTALLii, Ch. and Sch. Linnaea, ii. 226, t. vi. f. 
 
 25 (1827). 
 
 P. Pennsylvania^, Ch. and Sch. Linn. ii. 227 (1827). 
 P. pnmilns, Wolfg. in R. and S. Mant. iii. 354 (1827), fide. Ar. 
 
 Benn. Jour. Bot. xxix. 307. 
 P. Claytonii, Tuckerm. Am. Jour. Sci. and Arts, ist, ser. xlv. 38 
 
 (1843)- 
 
 Stems slender, compressed, mostly simple, generally from i to 
 3 feet high, but sometimes 6 feet according to the depth of the 
 water in which it grows. Floating leaves elliptical, sometimes 
 obovate, obtuse at the apex, sloping at the base into a short 
 petiole, I ^-3^2 inches long and 4-1 2 lines wide, 12-27 nerved. 
 These leaves sometimes number as many as 4 or 5 pairs at several 
 inches distance from each other on the upper part of the stem. 
 Submerged leaves linear, 2-ranked, 2-7 inches in length and 1-3 
 lines in width, 5 -nerved, the 2 outer lateral nerves nearly marg- 
 inal, the space between the two inner and the midrib evenly and 
 coarsely cellular reticulated. In young plants the submerged leaves 
 are often crowded close together, the internodes afterwards elon- 
 gating. Stipules obtuse, hyaline, nerved, keelless. Peduncles 
 about ,the thickness of the stem, 1-5 inches long. Spikes ^-i 
 inch long, fruiting freely. Fruit roundish-obovate, 1^-1% lines 
 long by i-i^ lines broad, 3-keeled, middle keel sharp, the sides 
 flat and distinctly impressed; style short, apical. Embryo coiled 
 i^ times. 
 
 Abnormal forms occur with stems bearing many short lateral 
 branches, and with branched peduncles. 
 
 As has been stated under No. 2, I regard this species as con- 
 forming so closely to the figures and description of the fruit of P. 
 Nuttallii, as given by Cham, and Sch., that I cannot question their 
 identity. Otherwise I should have adopted their name P. Pennsyl- 
 vanicus, given a little later in Linnaea, of which only the foliage is 
 described. The truth seems to be that only fruit was seen in the 
 one case and only foliage in the other, and these authors described 
 them under different names. 
 
 So far as known, this species is peculiar to this country. 
 
 Common in ponds and streams throughout Canada, and froirT 
 New England to Pennsylvania and South Carolina, and westward
 
 19 
 
 to Oregon. (Plate XXIX., showing submerged leaves on the 
 
 right.) 
 
 6. POTAMOGETOX ALPiNus, Balbis, Misc. Bot. p. 13 (1804). 
 
 P. mfcscens, Schrad. ap. Cham. Ad. Fl. Ber. p. 5 (1815). 
 
 As an illustration of the confusing extent to which synonymy 
 has been carried in this family of plants, Mr. Bennett enumerates 
 (Jour. Bot. xxvii., 242) 21 names given to this. species by differ- 
 ent authors. 
 
 Entire plant of a ruddy tinge, especially the leaves and 
 spikes. This is very apparent in clear water. Stems simple or 
 sparsely branched, somewhat compressed; internodes usually very 
 long. Floating leaves coriaceous, spatulate or oblanceolate, obtuse, 
 sloping into petioles 1-5 inches long, 17-21 nerved, mostly oppo- 
 site, the midrib with a chain-like areolation on each side. Sub- 
 merged leaves thin, semi-pellucid, the lowest sessile, the upper- 
 most petioled, opposite under the branches and peduncles, oblong- 
 linear or linear-lanceolate, obtuse or rarely acute, narrowing at 
 base, 3-12 inches long and 2-9 lines wide, 7-17 nerved. Stipules 
 broad, faintly bicarinate, with many fine nerves, pellucid on the 
 edges, obtuse or very rarely acute. Peduncles about the thickness 
 of the stem, 2-8 lines long, sometimes 3 or 4 or even more near the 
 summit of the stem. Spikes cylindrical, i-i l / 2 inches in length, 
 densely fruited, occasionally appearing compound. Fruit obovate, 
 lenticular, smooth, reddish in color, about I ^ lines long by I line 
 wide, 3-keeled, middle keel sharp, almost winged, sloping on each 
 side into obscure lateral keels; face arched and beaked by a short 
 recurved style; apex of the embryo pointing directly to the basal 
 end. It is stated by Dr. Robbins in Gray's Man. Ed. 5, that the 
 fruit is "pitted when immature." In mature fruit no pit is seen. 
 The nutlet shows smooth even sides, with a shallow depression 
 near the base of the facial edge, and two obscure furrows on the 
 back. This species, though common in Europe, while widely dif- 
 fused is rare in our country. 
 
 Greenland; Canada from Nova Scotia to Vancouver's Island 
 (Macoun); near Fort Yukon, Alaska (Kennicot); St. John's River, 
 Maine (Pringle); Barnet, Vt. (Dr. Blanchard); Brattleboro, Vt. 
 (Frost); Lake Champlain, on the Vermont and New York sides 
 (Faxon, Morong); State line, Western Massachusetts (Robbins);
 
 20 
 
 Niagara Falls, N. Y. (Morong); Delaware River, Belvidere, N. J. 
 
 (Britton); Beaver River, Mich. (Hill); Vermilion Lake, Minn. (L. H. 
 
 Bailey); National Park (Clifford Richardson); Utah (M. E. Jones); 
 
 Oregon (Howell). Attributed by Brewer and Watson in Bot. Cal. 
 
 to Montana, Colorado and California. July, August. (Plate 
 
 XXX.) 
 
 7. POTAMOGETON LONCHiTES, Tuckerm. Am. Jour. Sci. and Arts, 
 
 2d ser. vi. 226 (1848). 
 P. fluitans. Tuckerm. Am. Jour. Sci. and Arts, 2d ser. vii. 348 
 
 (1849), not Roth? 
 
 P. fluitans, Roth, Fl. Germ. i. p. 72 (1788)? 
 P. Amcricanus, Ch. and Sch. Linnaea, ii. 226, t. vi. f. 25 (1827)? 
 
 Stem slender, terete, much branched, elongated, 3 to 6 feet 
 and sometimes more in length. Floating leaves coriaceous, usu- 
 ually rather thin, elliptical, pointed at both ends, 2 to 4 inches 
 long and 6 to 14 lines wide, 17 to 24 nerved, on petioles 2 to 8 
 inches in length. Submerged leaves very thin and pellucid, often 
 with an irregular cellular-reticulated space on each side of the 
 midrib, 4 to 13 inches long by 2 to 12 lines wide, rather rounded 
 at base or tapering gradually into a petiole I to 4 inches long. 
 The stipules vary much in different plants, usually 3 or 4 inches 
 long, but often only I or 2 inches long, acuminate, acute or ob- 
 tuse, strongly or faintly bicarinate. Peduncles thickening up- 
 wards, 2 to 3 inches long. Spikes cylindrical, I to 2 inches long, 
 densely fruited. Fruit I ^ to 2 lines long, by I to I ^ lines wide, 
 obliquely obovate, face nearly straight or rarely slightly angled or 
 rounded, back 3-keeled, middle keel prominent, strongly rounded 
 or often with a projecting wing just under the curve of the style, 
 not impressed on the sides; style short, facial; embryo slightly in- 
 curved, the apex pointing slightly inside of the base. 
 Var. NOWEBORACENSIS, n. var. 
 
 With larger and thicker floating leaves, the blades 3 to 5*/ 
 inches long by i ^ inches wide, 20 to 24 nerved, abruptly pointed 
 or rarely obtuse at the apex and rounded or sloping at the base. 
 Peduncles sometimes 4 or 5 inches long and the spikes 3 inches. 
 The submerged leaves and fruit like those of the type. This form 
 occurs in Lake Erie, Lake Cayuga, Niagara river, Oneida Lake, 
 Lake Seneca, the Erie Canal near it, and in stagnant pools empty-
 
 21 
 
 ing into the same lake, New York. It is the plant described by 
 Tuckerman in Am. Jour. Sci. and Arts, 1. c., under the name of 
 "P.fluitans, Roth." 
 
 I have hesitated much in regard to the naming of this species, 
 but in the present confused state of opinion concerning the status 
 of P.fluitans, Roth, I can see no other method of disposing of it 
 except to retain Tuckerman's name lonchites as the type and to 
 regard the New York form as a variety. I have a large set of the 
 English plants from Mr. Fryer, named by him "P. fluitans, Roth," 
 and our typical form agrees very well with these, but as Mr. Fryer 
 states that the English plant is never known to fruit, and he has 
 reason to regard it as a hybrid, we cannot accept it as our lon- 
 chites, for that is most certainly not a hybrid, as it fruits abundantly 
 and occurs in widely separated localities, and often where neither 
 of the supposed parents are found. I have also numerous speci- 
 mens of the continental plant called by many authors P.flmtaiis, 
 Roth. Our variety Nav&boracensis corresponds very closely to 
 specimens sent me by Dr. Tiselius, collected in the river Neckar, 
 the fruit being almost identical with that of our species, and if I 
 could be sure that his plant is the true fluitans, my hesitation 
 would be at an end, but that is in dispute. The late Prof. Caspary 
 favored me with beautiful specimens collected in Russia, identical 
 with those of Dr. Tiselius, and labelled "P. fluitans, Roth," show- 
 ing the opinion of this celebrated botanist. To throw doubt upon 
 the determination, however, there come from France plants bear- 
 ing the same kind of foliage as these, but with a totally dissimilar 
 fruit, and still called "P.fluitans, Roth." Considering the fact that 
 Roth only describes the foliage of his plant, apparently never hav- 
 ing seen the fruit, that no authentic species of his naming has 
 ever been discovered, and that various European authors differ so 
 widely, there is no other course left but the one here adopted. 
 Of one thing I am certain, the plants from Dr. Tiselius and Prof. 
 Caspary are our New York species, and that is but a larger form 
 of our loncJdtes. I have little doubt, also, that the species the fruit 
 of which is figured and described by Cham, and Schlecht. under 
 the name of P. Anicricanus is our plant. 
 
 Widely diffused in this country. New Brunswick and Ontario 
 (Macoun). New England to Florida and Texas and westward to
 
 22 
 
 Washington and California. Also Mexico and Cuba. July-Oc- 
 tober. (Plate XXXI., showing a submerged leaf on the right.) 
 
 8. POTAMOGETON pAXONi, Morong. n. sp. 
 
 A plant collected by Mr. Edwin Faxon in the years 1880 and 
 1882 in Lake Champlain at Ferrisburg, Vt., which has been re- 
 ferred to P. rufcscens, but is evidently quite a different species. Mr. 
 Arthur Bennett, to whom I sent specimens, suggests in Jour. Bot. 
 xxviii, 301, that it may be a hybrid between P. rufesccns and P. 
 Nuttallii (Claytonii), and also states that it greatly resembles his P. 
 Griffitlni, but cannot with certainty be classed under that species. 
 If it is to be regarded as a hybrid, which may be the case, I should 
 much rather consider it the offspring of P. lonchites and P. 
 rufesccns, as both of those species abound in the vicinity, and on 
 the whole it more nearly resembles the former than any other 
 North American species. 
 
 Floating leaves numerous, thick, coriaceous, mostly obovate or 
 oblanceolate, bluntly pointed or obtuse at the apex and sloping 
 into the petiole at base, many of them obovate like those of mfcs- 
 cens, and often strikingly like those of spatlnil<zformis, 2-$ l / 2 
 inches long and 8-12 lines wide, 13-17 nerved, on petioles 2 to 6 
 inches in length. Submerged leaves oblong-lanceolate, acute or 
 sometimes obtuse, 3-5 inches long and 6-12 lines wide, 5-13 
 nerved, often with an irregular areolation on each side of the 
 midrib ; on petioles J/j-2 inches in length. The nerves run into 
 the apices of the leaves, and the numerous cross veins slope 
 slightly upward at a large angle from the midrib. Peduncles a 
 little thicker than the stem, 2 to 5 inches long. Spikes I to 2 
 inches long, densely flowered. No fruit found. 
 
 The plant occurs in the still waters of the lake and also in the 
 rapids of creeks emptying into the lake. 
 
 It is named in honor of Mr. Edwin Faxon, of Jamaica Plain, 
 Mass., who was the first to collect it. (Plate XXXII). 
 
 9. POTAMOGETON MEXICANUS, Ar. Bennett, Jour. Bot. xxv. 289 
 (1887). 
 
 I have seen only the fruit of this species. The following is Mr. 
 Bennett's description of the stem and foliage: " Rootstock creep- 
 ing; stems simple. Lower leaves 3-5 inches long, alternate strap- 
 shaped, elliptical, tapering at either end; petioles 3-5 inches long.
 
 23 
 
 Upper leaves 3-4 inches long, alternate (or occasionally opposite), 
 elliptical, coriaceous, with 14-16 principal ribs, and occasionally 
 secondary ones which fall short of the apex and anastomose with 
 the cross-veins; areolation distinct over the whole leaf; petioles 
 2-6 inches long. Peduncles 2 inches long, slightly thickening up- 
 wards. Fruiting spikes i-i^ inches long, rather few flowered." 
 
 The fruit of this species is very distinct. Drupe 2 lines long, 
 I y 2 lines wide, strongly tricarinate, the middle keel prominent, 
 sharp and denticulate, while the lateral keels are strikingly em- 
 bossed with protuberances; face slightly curved; style stout, short, 
 facial. 
 
 Named and described from specimens in the Herbarium of the 
 British Museum collected by Schmitz in the valley of Myrica, 
 Mexico, and at Berlin collected by Schaffner, Aug., 1854, in a 
 river near Chasseltepec, Mexico. (Plate XXXIII. The figure of 
 the plant is from a drawing of Mr. Bennett.) 
 
 IO. POTAMOGETON HETEROPHYLLUS, Schreb. Spicileg. Fl. Lips. 21 
 
 (1771). 
 
 P. gramincus, Kries, Nov. Ed. 2, p. 36 (1828), not L. 
 
 P. gramincHs, var. hetcrophyllus, Fries, Nov. Ed. 2, p. 35 (1828). 
 
 A very variable species. Stems slender, compressed, much- 
 branched, from i to 2 feet high, usually growing in quiet water. 
 Floating leaves coriaceous, oval or elliptical, short-pointed at the 
 apex and rounded or sloping at the base, occasionally sub-cordate, 
 8 lines to \y 2 inches long and 4-6 lines wide, with 10-18 nerves; 
 petioles 1-4 inches in length. Submerged leaves pellucid, sessile, 
 lanceolate or linear-lanceolate, acuminate or cuspidate, those of 
 the type rather stiff, 1-3 inches long and 1-6 lines wide, with 3-7 
 nerves, the uppermost often petiolate. Peduncles often thickened 
 upwards, 1-4, rarely 7, inches in length, often clustered at the top 
 of the stem. Stipules loose, spreading, obtuse, 2-keeled, 8-12 
 lines long. Spike ^-i}/ inches long, usually fruiting freely. 
 Fruit roundish or obliquely obovate, ^-i l /2 lines long by ^-i 
 line broad, slightly curved or angled on the ventral side, rounded 
 and indistinctly 3-keeled on the back, the obovate forms with an 
 inward basal curve on the face and an indentation running into it 
 from the centre of the sides; style short, obtuse, apical, rarely
 
 24 
 
 facial; apex of the embryo nearly touching the base, pointing 
 slightly inside of it. 
 
 The many forms of this species may be named as follows : 
 
 Forma GRAMINIFOLIUS (Fries), Morong. 
 var. graminifolius, Fries. Novit. 36 (1828). 
 
 This varies from the type in having delicate, flaccid, linear sub- 
 merged leaves from 2 to 5 inches long and 1-3 lines wide. It is 
 often found with the type and gradually runs into it. 
 
 Forma LOXGIPEDUNCULATUS (Merat), Morong. 
 P. longipcdunculatus, Merat, Fl. Paris. 
 
 This I had named forma elongatns until informed by Mr. Ben- 
 nett that it occurs in the work of Merat under the present name. 
 It has submerged leaves 1-2 inches long and 2-3 lines wide, 
 sharp-pointed, the internodes naked and extremely long, fre- 
 quently as much as 10 inches. Peduncles 3-6 inches long. 
 Floating leaves ovate. 
 
 I collected this in deep water in Lake Erie, near Buffalo, and 
 Lake Seneca, N. Y. Prof. L. H. Bailey has since obtained it in 
 Vermilion Lake, Minn., and Mr. F. V. Coville in Chenango River, 
 N. Y. 
 
 Forma MYRIOPHYLLUS (Robbins), Morong. 
 Var. ? mynophyllus, Robbins, in A. Gray, Man. Ed. 5, p. 487 (1867). 
 
 An interesting form with long running rootstocks which send 
 up dichotomously branching and very leafy stems. Submerged 
 leaves delicate, about I inch long by 2 lines wide, 3-5 nerved, 
 linear or the upper ones oblanceolate. Floating leaves elliptical 
 or lance-oblong. This form often throws up very long, naked, 
 thread like stems, which bear long-petioled floating leaves, while 
 the submerged leaves are on short lateral branches near the base. 
 These and the "early perishing submerged stem leaves" of which 
 Robbins speaks are found only in a mill pond at Apponaug, R. L, 
 the locality in which the form was first discovered, and are caused 
 by the frequent variation in the depth of the water, now drained 
 off and now suffered to rise. When the pond is low, the plants 
 spring up and bear floating coriaceous leaves which are suddenly 
 submerged by a rise in the water and very soon perish. The 
 plant in order to meet the new conditions throws up proliferous 
 stems which produce a new set of floating leaves.
 
 25 
 
 This form is also remarkable for its tuberous rootstocks, which 
 are very abundant. 
 
 I have collected this not only in Apponaug pond, but also in 
 Waushakum pond, Ashland, Mass., and Lake Quinsigamond, 
 Worcester, Mass. It occurs also in Lake Saltonstall, near New 
 Haven, Conn. (Prof. O. D. Allen.) 
 
 Forma MINIMUS, Morong. 
 
 A very rare form, with long, almost capillary stems and inter- 
 nodes 3 to 4 inches in length. Submerged leaves thickly clus- 
 tered on short, lateral branches, ^ to I inch long and scarcely ^ line 
 wide, acuminate, I -nerved, some of them with the nerve obscured. 
 Floating leaves ^ to I ]/ 2 inches long and 3 to 9 lines wide, lance- 
 olate, oval or ovate, usually clustered at the summit of the stem. 
 
 This form I collected in Spot Pond, Stoneham, Mass., and it has 
 also been detected in Lake Winnepesaukee, N. H., by W. F. 
 Flint. The minute submerged leaves, clustered on short, lateral 
 branches are quite striking. 
 Forma MAXIMUS Morong. 
 Var. inaxiinns, Morong, without description, Bull. Torr. Bot. Club, 
 
 xiii. 155. 
 
 All the parts greatly elongated. Stems sometimes 10 to 12 
 feet in length. Floating leaves often lanceolate and sharply 
 pointed, 3 to 4 inches long and 6 to 14 lines wide. Submerged 
 leaves 2 to 6^ inches long and 3 to 8 lines wide, 5 to 9 nerved. 
 Specimens collected by Prof. O. D. Allen, in Lake Whitney, 
 Conn., have large, oval, floating leaves with from 29 to 31 nerves, 
 and submerged leaves with 1 3 nerves. Peduncles 2 to 4 inches 
 long, usually much thickened upwards, often at right angles to the 
 stem, a peculiarity which I have observed in specimens from other 
 localities also. This form greatly resembles one sent by Dr. 
 Tiselius from Sweden, and named by him var. fluctuans. It com- 
 monly occurs in swiftly flowing water, to which fact the elonga- 
 tion of the parts is doubtless largely owing. 
 
 Charles river, Mass., Saranac river, Adirondacks, N. Y., and 
 Connecticut river, Deerfield, Mass. (Morong); Lake Vermilion, 
 Minn. (L. H. Bailey); Pine Plains, N. Y. (Hoysradt); Delaware 
 river, N. J. (Porter); flowing water, Busic river, Anticosti (Ma- 
 coun).
 
 Besides the localities of peculiar forms mentioned above, the 
 range of the species is indicated by the following stations. Com- 
 mon throughout Canada from the Atlantic to the Pacific and 
 from Maine and Vermont through New Jersey to North Carolina ; 
 Lake Huron (Macoun.); Sault Ste. Marie, Mich. (Morong); Chicago, 
 111. (Babcock); Armstrong's Grove, Iowa (Cratty); Sherburne Geyser 
 Basin, National Park (Clifford Richardson); Falcon Valley, Wash- 
 ington (Suksdorf); Salt Lake City, Utah (M. E. Jones); Ruby 
 Lake, Nevada (Watson). Attributed by Brewer and Watson, 
 Bot. Cal., to Soda Spring, near Mono Pass, Cal. (Plate XXXIV., 
 submerged leaves on the left.) 
 
 ii. POTAMOGETON spATHUL/EFORMis (Robbins) Morong. 
 P. gramineus, var. ^spatliulcefonnis, Robbins in A. Gray, Man. Ed. 
 
 5, p. 487(1867). 
 
 P. spathceformis, Tuck, in Herb. 
 P. varians, Morong in Herb. 
 
 Rootstock running, producing many branching stems 2-3 feet 
 high. Floating leaves obovate, sometimes elliptical, abruptly 
 acute at the apex and usually sloping at base, rather thin, 13-23 
 nerved, 1-2*^ inches long and 6-13 lines wide, on slender petioles 
 1-4 inches in length. Submerged leaves pellucid, spatulate-oblong 
 or linear-lanceolate, 2-4 inches long and 3-9 lines wide, 5-13 
 nerved, cuspidate or spinescent at the apex and sloping at base, 
 all sessile at first, with age subsessile or even petioled. The sub- 
 merged leaves are often reduced to phyllodia or forms with a very 
 narrow blade and a long acumination at the apex and base. Pe- 
 duncles often thickening upwards, 1-2 inches long. Stipules ob- 
 tuse, faintly keeled, the apex slightly cucullate and splitting on 
 pressure. Spikes large, densely flowered. Fruit like that of 
 hcterophyllus, about I line long by ^ line broad, roundish or 
 obliquely obovate, obscurely 3-keeled, with a curved or slightly 
 angled face ; style apical or facial ; embryo with the apex nearly 
 touching the base and pointing slightly inside of it. 
 
 This plant was discovered by Prof. E. Tuckerman as long ago 
 as 1850 in Mystic Pond, Medford, Mass., and named P. spathczforinis 
 in his herbarium. Dr. Robbins obtained it afterwards from the same 
 locality in 1856 and 1867, and published it as above cited. The 
 present writer visited the spot several times in 1879-81 and found
 
 27 
 
 it growing vigorously. No other locality for it is known in this 
 country. It is, however, common in Cambridgeshire, England, 
 and Mr. Fryer has kindly sent me a fine suite of specimens col- 
 lected in that locality. Here it has never been observed in fruit, 
 but it fruits, though not very freely, in England. The fruit, which 
 is characterized from British specimens, shows a near alliance to 
 P. licteropliyllus, from which, however, it differs considerably in 
 other points. Indeed, while it resembles heterophyllus on the one 
 side, it exhibits a decided likeness to P. angustifolius on the other, 
 and accordingly it has sometimes been ranked with the one species 
 and sometimes with the other. Mr. Fryer, whose opinion in any 
 matter relating to the Potamogetons of his district deserves great 
 weight, is inclined to regard this species as a hybrid between 
 keteropkyllus and angustifolius, and there are strong reasons for 
 suspecting that it may be a hybrid, such as the fact that the 
 anthers are usually either destitute of pollen, or possess only un- 
 potential pollen, and hence their inability to fertilize the stigmas, 
 and the limited area of its growth. But a weighty argument 
 against this view is the fact that neither of the supposed parents 
 occurs in Mystic Pond, and that it should be produced in localities 
 separated by the Atlantic ocean. 
 
 July-August. (Plate XXXV. The fruit is figured from British 
 specimens supplied by Mr. Fryer.) 
 
 1 2. POTAMOGETON iLLixoENSis, Morong, Bot. Gaz. v. 50 (1880.) 
 
 Stem from a thick running rootstock, stout, much-branched 
 above. Floating leaves opposite, numerous, thick, coriaceous, 
 4/4-5/6 inches long, 2-3^ inches wide, the apex with a short, 
 blunt point, rounded or sub-cordate or sometimes sloping at base, 
 oval or broadly elliptical, i8-2/-nerved. Petioles often broad and 
 flattened, 3-4 inches long. Submerged leaves numerous, usually 
 lanceolate, 4-8 inches long and I -2 inches wide, 13-19-nerved, 
 acuminate or the uppermost acute like the floating, occasionally 
 sessile, but for the most part sloping at the base into a short, 
 broad, flat petiole. These leaves are of a very dark green color, 
 with a conspicuous midrib, rarely reduced to phyllodia or to leaves 
 with a long, phyllodia-like apex and base, expanding into a narrow 
 blade in the middle.
 
 28 
 
 Stipules 2-3 inches long, obtuse, strongly bicarinate. Peduncles 
 usually thicker than the stem, sometimes thickening upwards, 2-4 
 inches in length. Spikes 1-2 inches long, fruiting freely. Fruit 
 roundish or obovate, i l / 2 -2 lines long and i-i l / 2 lines broad, dor- 
 sally 3-keeled, the middle keel sharp ; straight or curved on the 
 face ; style facial, short, bluntish ; apex of the embryo pointing 
 transversely inwards. 
 
 This species is evidently allied to Ittcens in habit, and with that 
 species, P. angustifolius, P. spathul&forinis and P. hcterophyllns, 
 forms a very natural group, but it is clearly distinct from all of 
 them in its vigorous growth, its abundant foliage, its ample float- 
 ing and submerged leaves, and its large, strongly 3-keeled fruit. 
 
 In two or three recent publications some doubts have been 
 thrown upon the specific status of this plant, which, considering 
 its mirked individuality, are, to say the least, rather surprising. 
 Mr. Hill, in Bull. Chicago Ac. for 1891, p. 125, says: "* * * 
 a doubtful species at best." It seems to me not half so doubtful 
 as many other species of good standing that might be mentioned. 
 In fact, its peculiarities are strikingly manifest. 
 
 In A. Gray, Man. Ed. 6, it is said to be " very near amplifolius" 
 a species with which it has very few characters in common. The 
 eminent Scandinavian Potamogetonist, Dr. Tiselius, whose au- 
 thority upon Northern European species no one will question, 
 identifies it with P. lonchites (sub. nom. P. fluitans, Roth.*), but it 
 certainly bears little resemblance to any form of that species grow- 
 ing in this country. Nor does it square with any of the examples 
 of this species sent to me from Sweden by my distinguished 
 friend. In his article he compares the floating leaves of my species 
 with those of autumnal shoots of P. fluitans, and, finding them 
 similar, rather hastily, I think, pronounces them specifically identi- 
 cal, but he overlooks the fact that non-fruiting autumnal growths 
 are nearly always abnormal. Were there no other differences, the 
 entire dissimilarity between these two species in the stipules, sub- 
 merged foliage and fruit are quite sufficient to separate them 
 widely. 
 
 Our plant was first discovered by Mr. H. N. Patterson in the 
 
 *See Nordstedt's Botaniska Xotiser for 1887, p. 263.
 
 29 
 
 Mississippi river bottoms at Oquawka, 111., and sent by him to 
 Prof. E. Tuckerman, who in turn transmitted it to Dr. Robbins, by 
 whom it was considered as an extraordinary floating-leaved form of 
 P. luccns. It has since been found by Mr. R. I. Cratty in a small 
 pond at Armstrong's Grove, Emmet county, Iowa. Both of these 
 gentlemen have supplied me with numerous specimens in all stages 
 of growth, from which it has been easy to deduce the characters. 
 I have not seen it from any other locality, though it should be ex- 
 pected in all the neighboring regions. Fruits in August. (Plate 
 XXXVI.) 
 13. POTAMOGETON ANGUSTiFOLius, Berch. and Presl, Rost. p. 19 
 
 (1821), fide A. Bennett. 
 P. Zizii, Roth, En. PI. Germ. {.531 (1827). ' 
 /'. hctcrophyllus elongates, M. and K. Deut. Fl. i. 845 (1823). 
 P. luccns, var. heterophyllus, Fries, Nov. Ed. 2, 34 (1828). 
 P. luccns var. minor, Nolte in Hans. Ex. No. 521, British Mus., 
 
 fide A. Bennett. 
 
 Stem slender, branching. The branches rise from the stem at 
 an acute angle, occasionally at a right angle. Floating leaves 
 coriaceous or semi-coriaceous, rarely shining on the upper surface, 
 elliptical, pointed or abruptly acute at the apex, sloping at base, 
 the blade \y 2 to 4 inches long and 6 to 12 lines wide, with 13 to 
 21 nerves; petioles commonly shorter than the blade, but some- 
 times attaining a length of 6 inches. Submerged leaves mostly 
 lanceolate or oblanceolate, occasionally oblong-spatulate, thin, pel- 
 lucid, acute or cuspidate, sometimes acuminate, often wavy or crispy 
 and minutely serrulate near the apex, sessile or the uppermost 
 shortly petioled, 2-6 inches long and 3-15 lines wide, 7-17 nerved. 
 Stipules 6-1 8 lines long, sometimes very broad at the base, obtuse, 
 2-keeled, loose and spreading as in P. JieteropJiyllns. 
 
 Peduncles mostly straight and erect, stout, thicker than the 
 stems, sometimes thickening upwards, 2^-6 inches long. Spikes 
 1-2 inches long, more in the habit of fruiting in Europe than in 
 this country. Fruit obliquely obovate, i^-i^ lines long and 
 about i line wide, the face usually straight, occasionally a little 
 angled, dorsally 3-keeled in the mature dried fruit; style short, 
 blunt, facial; cotyledonary apex nearly touching and pointing 
 directly to the end of the radicle. The fruit strongly resembles 
 that of P. heterophyllus.
 
 30 
 
 This species seems to be intermediate between P. Jieteropliyllus 
 and P. lucens. It may generally be distinguished from the former 
 by its larger size, by floating leaves of thinner texture and more 
 sloping at the base, by its larger, more sharply pointed and 
 strongly undulate submerged leaves and larger fruit. From P. 
 lucens it may be distinguished by its floating leaves, which are 
 lacking in P. lucens, as well as by its smaller fruit and other char- 
 acteristics. It usually sends up coriaceous floating leaves late in 
 the season. It flowers freely, but seldom fruits in the United 
 States. It commonly occurs in rather shallow and quiet waters, 
 but is not widely diffused. 
 
 A form collected by Prof. Macoun in Methy Lake, Lat. 57 n., 
 Canada, and which I have not seen, is thus named and described 
 by Mr. Bennett in Jour. Bot. for May, 1891, p. 151. 
 
 " Var. Metkyemis. Differs from any form of the type in America 
 or Europe by the long, narrow middle leaves. The upper leaves 
 are oval, semi-coriaceous, with long stipules, combining the habit 
 of longifolius, Gay. and the lucens No. 607 of Herb. Fl. Ingricae; 
 fruit smaller, and the embryo more curved." 
 
 The type has been found in Canada in the Provinces of Ontario 
 and Quebec (Macoun) ; Fresh Pond, Cambridge, Mass. (Morong) ; 
 Wenham, Mass. (Faxon, Morong); Pine Plains, N. Y. (Hoysradt); 
 Lake Cayuga, N. Y. (Dudley) ; Oneida and Seneca Lake, N. Y. 
 (Morong); Delaware river, above Phillipsburg, N. J. (Porter); 
 Pine Station, 111. (Hill) ; Frankfort, Mich. (Hill) ; Lewis Lake, 
 Wyoming (Clifford Richardson) ; Montana (Hayden Survey) ; 
 Florida (Curtiss) ; Texas (Reverchon, Wright). Common in Eng- 
 land and Continental Europe. (Plate XXXVII.) 
 
 14. POTAMOGETON LUCENS, L. Sp. PI. 126 (I/53). 
 
 Stem thick, branching below and often with masses of short 
 leafy branches at the summit. Destitute of propagating buds or 
 glands. Leaves all submerged, elliptical or lanceolate, uppermost 
 often oval, rounded at both ends and merely mucronate, usually 
 acute or acuminate and cuspidate, sessile or short petioled, 2^4-8 
 inches long and 8-20 lines wide. The nerves are commonly 1 3, but 
 sometimes fewer, and the tips frequently serrulate. They are 
 rarely shining, though the name would imply otherwise. Stipules 
 1-3 inches long, obtuse, bicarinate, commonly loose and spread-
 
 31 
 
 ing, sometimes very broad. Peduncles 3-6 inches long, scarcely 
 thickening upwards. Spikes 2-2^ inches long, very thick cylin- 
 drical, fruiting freely late in the season. 
 
 Fruit about I ]/ 2 lines long and I ^ lines broad, roundish ; keels 
 small, often obscure ; face usually with a slight inward curve at the 
 base ; style nearly apical ; apex of embryo pointing transversely 
 inwards, but the curve less than in No. 12. 
 
 The typical form of our species approaches most nearly to the 
 European form called var. ovalifolius, M. and K., as the uppermost 
 leaves are generally oval or ovate in outline. Those remarkable 
 forms, so common in Europe, and known as var. cornutus, Presl., 
 var. longifolius, Gay, and var. acuniinatns, ScJinin. never occur in 
 our country, so far as I am aware, but they are approached by the 
 submerged foliage of P. Illinocnsis* 
 
 Var. CONXECTICUTENSIS, Robbins,in A. Gray, Man. Ed. 5. 488 
 (1867.) 
 
 This seems to be a good variety, but very rare. As stated by 
 Dr. Robbins, the stems are flexuous, the leaves acuminate, and the 
 fruit larger than in the type (ij^-2 lines long and about \y 2 lines 
 wide), distinctly tricarinate and with a facial style. It has been 
 found only in Saltonstall's Pond, East Haven, Conn. (Robbins), 
 and Pine Plains, N. Y. (Hoysradt). Forms resembling this were 
 obtained by E. Faxon in Lake Dunmore, Vermont, but without 
 fruit. 
 
 The typical lucens is not very common in this country. It 
 occurs rarely in Nova Scotia and Ontario (Macoun) ; Fresh Pond, 
 Cambridge, Mass. (Morong) ; Lakes Cayuga, Onondaga and 
 Oneida, N. Y. (Dudley, Morong.); Pine Station, Indiana (Hill). 
 Attributed to Fla. by Chapman (Chap. Fl.) ; and to Mission 
 Dolores, Cal. by Brewer and Watson (Fl. Cal). It has also been 
 collected by Pringle in the State of Michoacan, Mex. (No. 3327, 
 wrongly named P. Zizii). Cuba (Wright). Common throughout 
 Europe, Asiatic Russia, and other parts of Asia. (Plate XXXVIII.) 
 
 *Mr. A. Bennett in his recently published list of the Potamogetons in the Vienna 
 Herbarium (Ann. der. K. K. Naturhist. Hoffmus. for 1892, p. 290), notes in that 
 collection a specimen of P. longifolius, Gay, gathered in Oregon by Dr. Lyall.
 
 32 
 
 15- POTAMOGETOX PRAELOXGUS, Wulf. in Rom. Arch. iii. 331 
 
 (1805). 
 
 P.flexuosus, Schleich. and Wredow, Meklenb. Fl. (1807). 
 P.flcxicaulis, Dethard, in Strelitz. Anz. 1809. n. 50. 
 
 Stem white, flexuous, flattened, much branched, growing in 
 deep water, sometimes 6 to 8 feet in .length. Leaves all sub- 
 merged, oblong or oblong-lanceolate, obtuse and cucullate at the 
 apex, splitting on pressure, semi-amplexicaul, of a bright green 
 color. They are from 2 to 12 inches in length, and from y 2 to 
 1 1/ inches wide, with only 3 or 5 main and from 7 to 17 finer 
 nerves, sometimes with a narrow reticulated space on each side of 
 the midrib. Stipules white, scarious, obtuse and commonly 
 closely embracing the stem. Abnormal specimens with spread- 
 ing stipules 2-3 inches long have been collected in Maine by Miss 
 Kate Furbish. Peduncles from 3 to 15 inches and occasionally 
 as much as 20 inches long, erect, straight, about as thick as the 
 stem, and often very numerous. Spikes 1-2 inches long, thick, 
 cylindrical, densely fruiting. Fruit dark green, obliquely obovate, 
 2,-2.y 2 lines long and 1^-2 lines wide; the back much rounded, 
 often with the upper curve nearly as high as the style. Middle 
 keel sharp and prominent, sloping on the sides to rather obscure 
 lateral keels; face straight or nearly so; style short, obtuse, facial; 
 apex of embryo pointing directly to the base. 
 
 This species fruits in our country in June and July, and usually 
 withdraws its stems beneath the water as soon as the fruit is set. 
 Hence the difficulty of obtaining good fruit unless dredging is 
 resorted to. 
 
 Deep water, lakes and ponds, Nova Scotia, New Brunswick, 
 Ontario and Vancouver's Island (Macoun's Cat.) ; Shelburne Pond 
 Vt. (Pringle) ; Wenham and Fresh Ponds, Mass. (Morong) ; Bantam 
 Lake, Litchfield, Conn. (Morong) ; Lake Salstontall, Conn. (Prof. J. 
 A. Allen); Canaan, Conn. (Robbins) ; Budd's Lake, N. J. (Porter); 
 Lake Canandaigua, N. Y. (Morong) ; Maltowah Lake and Chen- 
 ango River, N. Y. (Coville) ; Frankfort, Mich. (Hill) ; along the 
 Great Lakes to Lake Superior (Robbins) ; Vermilion Lake, Minn. 
 (L. H. Bailey); Iowa (Arthur's Cat.); National Park (Clifford 
 Richardson); Sierra Co., Cal. (Brew, and Wats. Bot. Cal.). (Plate 
 XXXIX.)
 
 33 
 
 l6. POTAMOGETON PERFOLIATUS, L. Sp. PI. 126 (1/53). 
 
 Stems slender, from running rootstocks which throw up many 
 shoots, much branched, often with many short lateral branches 
 along the main stem. Leaves very variable in shape and size, 
 mostly ovate or rounded, sometimes lanceolate, usually obtuse, 
 sometimes acute at the apex, amplexicaul and cordate at base, 
 meeting around the stem. They are never cucullate, as in the 
 preceding species, and never known to produce propagating buds 
 or glands. They are often crowded upon the stem, but more 
 commonly separated at a considerable distance, generally alter- 
 nate, but opposite under the nodes of the branches. The typical 
 European forms have large rounded or ovate leaves about 2 inches 
 long by \ l /2, inches broad, varying from this to narrow and elon- 
 gated forms l />-\% inches long and 4-15 lines in width, and 13- 
 27-nerved. The full type is rather rare in this country, the greater 
 part of our forms being small leaved, and west of New England run- 
 ning into the form known as Var. lanccolatus, Robbins. As found 
 here the typical plant has leaves varying from 5 to 1 5 lines long 
 and from 3 to 12 lines wide, usually obtuse and minutely serrulate 
 near the apex. Peduncles I j^ inches long, about the same thick- 
 ness as the stem, usually erect or slightly spreading, running in the 
 axils of the leaves for a long distance along the upper part of the 
 stem. Spikes 8-12 lines long, often flowering and fruiting under 
 water. Fruit obliquely obovate, i^-i^ lines long by I line or a 
 little more in breadth, obscurely tricarinate on the back, the face a 
 little curved outwardly towards the top, the sides \vith a shallow 
 indentation which runs into the face ; style nearly facial ; embryo 
 slightly incurved or with its apex pointing directly towards the 
 base. 
 
 Var. RICHARDSONII, Ar. Bennett, Jour. Bot. xxvii. 25 (i! 
 Var. lanceolatits, Robbins, in A. Gray, Man. Ed. 5, 488 (1867). 
 
 Mr. Bennett notes that the name of Robbins is preoccupied by 
 a different form of Blytt in Norges Flora (1861), and proposes the 
 present name in honor of the Arctic explorer, Dr. Richardson, 
 " who seems to have been the first to point out the difference from 
 the European forms in the ' Appendix ' (Botany) to Franklin's Ex- 
 pedition."
 
 34 
 
 Leaves of this variety lanceolate, from i to 4^ inches long and 
 4-8 lines wide at the broadened amplexicaul base, often curving 
 inwards towards the apex, and from 13 to 23-nerved. Leaves 
 from North Hero, Lake Champlain (Morong), and Sault Ste. 
 Marie, St. Mary's River, Mich. (Hill), measuring 4^ inches in 
 length, are the longest that I have ever seen. The fruit is some- 
 what larger than in the type, measuring about i ^ lines long by 
 I *^ lines wide. 
 
 Forms found in Wenham Pond, Mass., greatly resemble P. 
 nitcns, Webber, of Europe, and are considered to be this species 
 by Dr. Tiselius. They also bear a strong resemblance to P. per- 
 foliatus, var. Jacksoni, Nees, of England, which is regarded as a 
 form of nitens by Prof. Babington. They have oblong leaves i- 
 \y 2 inches long and 4-9 lines wide, obtuse, 7-i3-nerved, not ser- 
 rulate, semi-amplexicaul, with very slender, laterally much-branched 
 stems. 
 
 Common in Canada from Nova Scotia to Ontario (Macoun). 
 In the United States it occurs in nearly all parts of the country 
 from Maine to Florida, and west to the Pacific. The variety 
 occurs in Ontario, Canada, and thence westward, and from Lake 
 Champlain, Eastern New York and Delaware westward to Oregon 
 and California, being the most common Western form. In still, 
 shallow or deep water. July-September. (Plate XL. Var. Rich- 
 ardsonii is figured on the right). 
 
 17. POTAMOGETON MvsTicus, Morong, Bot. Gaz. 5, 50 (1880). 
 
 Whole plant very slender and delicate. Stems from a creep- 
 ing rootstock which throws up many shoots, irregularly branching 
 above, nearly filiform, terete, 1-3 feet high. Leaves all submerged, 
 scattered, oblong-linear, \-\y> inches long and 1-3 lines wide, 
 5-7-nerved, obtuse and rarely with minute serrulations near the 
 apex, abruptly narrowing at the base and sessile or partly clasping. 
 Stipules obtuse, about 6 lines long, hyaline, with many fine nerves, 
 mostly deciduous, but sometimes persistent and closely sheathing 
 the stem. Spikes few, capitate, 4-6-flowered, on erect peduncles 
 from i to 2 inches in length. No ripe fruit has ever been found, 
 but one or two immature drupes indicate that it is obovate, min- 
 ute, scarcely ^ of a line long by l / 2 a line broad, obscurely 3- 
 keeled on the back, a little beaked by the slender recurved style.
 
 35 
 
 Since I obtained this from Mystic Pond, Medford, Mass., in 1879, 
 I have visited the locality for several years in succession, and, 
 though I have always found the plant growing vigorously, yet it 
 has shown no signs of prefecting fruit. In the year 1887 I found 
 it growing in Miacomet Pond, Nantucket, under water about 3 
 feet deep, but it was entirely without flowers or fruit. 
 
 It is closely allied to P. perfoliatus in habit, with which it is asso- 
 ciated in growth, but very unlike that in foliage, and scarcely one- 
 third as stout in any of its parts. August-September (Plate XLI). 
 
 1 8. POTAMOGETON CONFER vo I DES, Reichb. Icon. Fl. Germ. et. Helv. 
 
 vii. 13 (1845)- 
 P. trichoides, A. Gray, Man. ed. I p. 457 (1848). Tuckerm. Am. 
 
 Jour. Art and Sci. 2 ser. vii, 358 (1849), not Cham. 
 P. Tuckermani, Robbins in A. Gray, Man. Ed. 2. 434 (1856). 
 
 Mr. Bennett states in Jour. Bot. xxviii. 92, that he has seen a 
 specimen of this species in Gay's Herb, at Kew under Reichen- 
 bach's name, and that it is undoubtedly the same as P. Tuckermani, 
 Robb. The description of Reichenbach corresponds very well to 
 our plant. There is here a good illustration of the danger of determin- 
 ing names without corroborating specimens, for Tuckerman, one of 
 the most minute and careful observers, says in his paper upon P. 
 triclioidcs: "I have seen no specimens of the European plant, but 
 Chamisso's minute description, and his figure of the fruit leave little 
 or no doubt of the identity of ours with it," and yet he was mis- 
 taken. 
 
 Stem from a creeping rootstock, slender, terete, much-branched, 
 the upper branches repeatedly dichotomous, 6-18 inches high. 
 Leaves very delicate, flat, setaceous, \-2 l / 2 inches long, the 
 broadest scarcely %. nne wide, tapering to a long hair-like point, 
 i-3-nerved, often with a few cross ribs or coarse reticulations, of a 
 bright green color, a little yellowish tinted. Stipules delicate, 
 obtuse, 2-3 lines long. Peduncles terminal, 2-8 inches long, straight 
 and erect, somewhat thickened upwards, sometimes with a short 
 lateral branch bearing a spike. Spikes capitate, 3 or 4 lines long; 
 Fruit thick with a shell roundish-obovate, i-i y z lines long and about 
 as wide ; back sometimes a little angular or sinuate, 3-keeled, the 
 middle keel sharp and prominent ; face notched near the base ; 
 sides impressed with a shallow indentation which runs into the
 
 36 
 
 notch of the face ; style short, apical ; embryo circle complete, the 
 apex nearly touching the base a little inside of its end. 
 
 A rare species growing in the shallow water of ponds. Round 
 Pond, York, Me. (Fernald); Franconia Notch, N. H. and a small 
 pond on Mt. Willey, 3,003 feet alt. (Faxon); Uxbridge, Mass. 
 (Robbins, Morong) ; New York (Torrey) ; common in N. J.; Great 
 Lake, Carbon Co., Pa. (Porter). (Plate XLII.) 
 
 19. POTAMOGETON CuRTissn, Morong, Bull. Torr. Bot. Club, xiii. 
 
 145 (1886). 
 
 Stems simple or branched, capillary, a foot or more in height, 
 the internodes long and naked. Leaves 6-17 lines long, almost 
 setaceous, many of them less than ^ of a line and none y 2 a line 
 broad, tapering to a long, hair-like point, the midrib with 2 deli- 
 cate nerves or a loosely-reticulated space on each side of it. 
 Stipules hyaline, obtuse, 3 or 4 lines long, deciduous. Peduncles 
 3-6 lines long, somewhat clavate, erect, axillary and racemosely 
 disposed, 5 or * more of them at intervals of one or two inches 
 along the upper part of the stem. Spikes capitate, 2 or 3 lines 
 long, 3-6-flowered. Fruit not seen. 
 
 Collected by Mr. A. H. Curtiss in Blackwater River, and a 
 " tidal creek" in Northwest Florida, May and June, 1886, the only 
 known locality for it. (Plate XLIII. A magnified leaf is figured 
 on the right.) 
 
 20. POTAMOGETON CRISPUS, L. Sp. PI. 126 (1753). 
 Stems branching, compressed. Leaves 2-ranked, linear-oblong 
 or linear-oblanceolate, sloping at base, sessile or semi-amplexicaul, 
 obtuse, serrulate, crisp, ^-4 inches long and 3-7 lines wide, 3-7- 
 nerved, the midrib often compound and the outer nerves very near 
 the margin. Stipules small, scarious, obtuse, early perishing. 
 Peduncles 1-2 lines long, frequently recurved when in fruit and 
 sometimes very numerous. Spikes about half an inch long, and 
 looking very bristly with the long-beaked drupes when in fruit. 
 Fruit ovate, about \ l / 2 lines long and I line or a little more in 
 width, having 3 rounded keels on the back, the middle one with a 
 small projecting tooth near the base, a slightly curved face, and a 
 curved facial style nearly as long as the drupe ; the shell thick and 
 corky, containing a small embryo, the apex of which points 
 directly towards the end of the radicle.
 
 37 
 
 This species in our country propagates itself mainly by winter 
 buds, of which there are two kinds. The rarer kind is spicular in 
 form, being simply a fragment of the stem, shrunken or sharpened 
 at the ends, with 2-6 buds upon it in the axils of the decayed 
 leaves. The more common form is a thick, rigid body composed 
 of the ends of the branches or stems, in which the upper portion 
 is swollen, hardened and surrounded by the bases of the leaves, 
 which are also much enlarged and indurated, and reduced to a 
 triangular shape, several buds being left in the axils. The lower 
 end becomes sharpened and is so easily detached that a mere jar 
 shakes it off the stem. The whole bud looks like a burr, and when 
 separated from the stem floats away bottom side up or sinks into the 
 mud . The new plant is formed by the development of one of the buds 
 which throws out .roots as it grows. It occurs in fresh and brackish 
 or tide water. Confined to a strip along the Atlantic coast from 
 Arlington, Mass., to James City, Virginia. It also runs inland in 
 fresh water as far as Lancaster, near the Susquehanna River, Pa. 
 (Porter), and the Lakes Keuta and Seneca, in the centre of New 
 York. Introduced from Europe, where it is common.* (Plate 
 XLIV. The two kinds of propagating buds are shown on the 
 left.) 
 
 21. POTAMOGETON zosTER/EFOLius, Schum. Enum. PI. Saell. 50, 
 
 168 (1801). 
 
 P. cojnplanatns, Willd. Mag. Berl. Fl. iii. 248 (1809). 
 P. coinpivssus, Fries, Nov. Ed. 2. 44 (1828), not L. Herb. 
 P. cuspidatus, Schrad. in Smith's Eng. Bot. i. 235 (1828). 
 
 Stem very much flattened, sometimes winged, widely branch- 
 ing. Leaves linear, obtuse and mucronate or shortly acute, with 
 3 principal nerves and many fine ones, the midrib often compound, 
 2-12 inches long and 1-2 inches wide. Stipules scarious, obtuse, 
 finely nerved, soon perishing. Peduncles i ^-4 inches long ; 
 spikes cylindrical, about y 2 inch long, 12-15 flowered. Fruit 
 obovate, with a broad base, 1^-2 lines long and \%-\y 2 lines 
 wide, 3-keeled on the back, lateral keels somewhat obscure, the 
 
 * Probably of recent introduction, as it seems not to have been known to the 
 older botanists, Rafinesque, Michaux, Pursh, Xuttall, Barton and others who col- 
 lected extensively in the region where it grows during the early part of this century.
 
 middle one often slightly toothed or undulate and with a projec- 
 tion at the base; face arched, beaked with a short, recurved style; 
 embryo slightly incurved. 
 
 The propagating buds of this species are very unlike those of 
 No. 2O, consisting only of the ordinary terminal leaf bud which 
 drops off near the end of the branch, sinks to the bottom and rests 
 in the mud during the winter. It is, however, a very common 
 source of propagation. 
 
 An elegant plant, with bright smooth leaves in fascicles at the 
 summits of the branches. It may be distinguished from other 
 North American species, and from Heteranthcra graminea with 
 flowerless forms of which it is sometimes confounded, by the nu- 
 merous fine nerves on the leaves. 
 
 In still or slowly moving water in Northern regions. New 
 Brunswick to the Saskatchewan, Canada (Macoun); Vermont to 
 New Jersey and westward to Iowa, Lake Superior and Oregon 
 (Hall, No. 491, fide Brew, and Wats. Bot. Cal.\ Common in 
 Europe. July, August. (Plate XLV.) 
 
 22. POTAMOGETON HiLLii, Morong, Bot. Gaz. vi. p. 290 (1881). 
 
 Stems slightly compressed, slender, widely branching, 1-2 feet 
 in height. Leaves linear, acute or abruptly acute and cuspidate, 
 often almost aristate, i-2}/ inches long and y 2 -i % lines wide, 3- 
 nerved, the lateral nerves delicate and nearer the margins than the 
 midrib, the midrib below often compound. Stipules whitish, 
 many-nerved, obtuse, 3-5 lines in length. Peduncles about half 
 an inch long, erect or slightly recurved, more or less clavate. 
 Spikes capitate, 3-6 fruited. Fruit obliquely obovate, obtuse at 
 the base, 1^-2 lines long by i-i */ lines broad, tricarinate on the 
 back, the middle keel sharp and more or less undulate, flat on the 
 sides, the face slightly arched ; style nearly facial, short, recurved ; 
 embryo apex pointing transversely inwards. 
 
 There are two forms of this species, the one biglandular at the 
 base of the leaves, and the other glandless. I found it growing in 
 the small pot ponds of Manistee, Mich., each pond having its own 
 form and apparently never mixing. In general appearance similar 
 to the large forms of P.foliosus, but allied by its peduncles, spikes 
 and fruit to P. obtusifolius and P. zostcrafolius , and still more
 
 39 
 
 closely to the European P. acntifolius, Link, to which in these 
 respects it bears a close resemblance. 
 
 A rare species growing in pools and ponds, and so far as 
 known, peculiar to the United States. Lake Cayuga and near Free- 
 ville, N. Y. (Dudley); Pine Plains, N. Y. (Hoysradt) ; Manistee, 
 Mich. (Hill, Morong); Ashtabula, Ohio (Hill). (Plate XLVI.) 
 23. POTAMOGETON FOLiosus, Raf. Med. Rep. 2d Hex. v. 354(1808). 
 P. gramincus ? MX. Fl. i. 102 (1803), not L. 
 P. pauciflorus, Pursh, Fl. i. 121 (1814). 
 
 Pursh's name, which this species has borne so long, must be 
 surrendered, not only because it had been antedated by that of Raf- 
 inesque, but also because it had been used by Lamark as long ago 
 as 1 778 (Fl. Franc, iii. 209, No. 798) as a synonym of P. densus, L. 
 
 A variable species peculiar to North America. Stems flat- 
 tened, much-branched, i to 3 feet high. Leaves 1-2 inches long 
 and i^-i line wide, acute, 3-nerved, not glandular at the base. 
 Very delicate forms are found, especially near the Atlantic coast, 
 which are scarcely more than 6 inches in height, the stems fili- 
 form, the leaves not over 8 lines long by % line wide, the lateral 
 nerves obscure or even obsolete. From this it rises into the 
 coarser forms which are more common inland and towards the 
 west. Stipules white, hyaline, obtuse, sometimes acute, 6-10 lines 
 long. Peduncles more or less club-shaped, erect, about l / 2 inch 
 long. Spikes about 4-flowered. Fruit impressed with a shallow 
 pit on each side when young, but even when fully mature,' lenticu- 
 lar, or nearly orbicular, 3^-1 line in diameter; 3-keeled on the 
 back, the middle keel winged, sinuate-dentate, often with project- 
 ing shoulders or teeth at each end ; face strongly angled or arched, 
 sharp or alate, often with a sharp, projecting tooth at the base; 
 style nearly apical, straight or recurved ; embryo curve complete, 
 the apex nearly touching the basal end. The fruit rarely ap- 
 proaches that of P. pusillus, being obliquely obovate, about i line 
 long and 3^ line wide, the wing on the middle keel narrow and 
 not dentate, but still it may always be distinguished by being more 
 or less crested. This species is also in very rare cases furnished 
 with reproductive buds and minute glands like those of pnsillus. 
 Var. NIAGAKKNSIS (Tuckerman) A. Gray, Man. ed. 2. 435 (1856). 
 P. Niagarciisis, Tuckerm. Am. Jour. Sci. 2 ser. vii. 354 (1849).
 
 40 
 
 Larger than the type, stems 2-3 feet in height, leaves some- 
 times over 3 inches in length and I line wide, 3-5 -nerved. 
 Stipules longer and occasionally acute. Spikes 8-12 flowered. 
 Mainly distinguished by its large size. This form, which is the 
 coarsest in the species, was originally discovered by Prof. Tucker- 
 man in the rapids above Niagara Falls, and was considered by him 
 a good species, but it seems to me too near foliosus to take 
 specific rank. For many years it seemed to have disappeared 
 from the original locality until the writer found it in abundance in 
 a sluice way between the Falls and the village on the American 
 banks. It has recently been collected by Mr. F. V. Coyille in the 
 United States expedition to Death Valley, California. 
 
 Var. CALIFORNICUS, Morong, Bot. Gaz. x. 254 (1885). 
 
 This form is distinguished by its bushy, vigorous growth and 
 large thick stem which is strongly flattened and sometimes winged, 
 often y 2 line wide. Many stems, thickly clustered, rise from the 
 roots. Leaves not so long or broad as in the preceeding variety, 
 but with a dilated mid-rib, reminding one of P. obtusifolius, and 
 frequently 5-nerved at the base. Peduncles 4-6 lines long, erect, 
 clavate, flattened. Spikes often ripening 12 strongly marked fruit. 
 Collected in San Bernardino county, Cal. by the Parish Brothers, 
 and by D. Cleveland at San Diego. 
 
 The species has a wide range, occurring in Canada from New 
 Brunswick to British Columbia (Macoun); New England to Florida 
 and New Mexico and westward to Oregon and California. July- 
 September. (Plate XLVII. Two common forms of the fruit are 
 figured.) 
 
 24. POTAMOGETON OBTUSiFOLius, M. and K. Deut. Fl. i. 855 (1823). 
 P. gramineus, Sowerby, Eng. Bot. iii. t. 2253 (1794), not L. 
 P. compressus, Wahl. Fl. Suec. i. p. 107 (1824), not L. 
 
 Stem usually slender, compressed, branching widely, especially 
 towards the summit. Leaves linear, 2-3 inches long and y 2 -2, 
 lines wide, obtuse, often mucronate, usually 3-nerved, sometimes 
 5- and rarely 7-nerved, biglandular at base, the glands large and 
 translucent, the midrib broad and frequently compound. Stipules 
 white or scarious, many-nerved, obtuse, 6-9 lines long, often as 
 long as or longer than the internodes. Peduncles numerous, y 2
 
 41 
 
 i y 2 inches long, slender, erect, rising from the axils of the branches. 
 Spikes 3-4 lines long, ovate, continuous, 5-8 flowered. Fruit 
 obliquely obovate, about \]/ 2 lines long and I line wide, 3-keeled, 
 middle keel distinct; face straight or nearly so; sides with a slight 
 impression which runs into the face; style short, blunt, nearly 
 facial ; embryo with the apex pointing a little inside of the base. 
 In North American forms the fruit is slightly longer and narrower, 
 and the embryo more incurved than in the European plant. 
 Rarely producing propagating buds. 
 
 Non-fruiting specimens of P. major are liable to be con- 
 founded with this species. For the distinctions see under that 
 species. 
 
 Not very common in this country. Ponds and still waters. 
 Quebec and Methy River, Lat. 57 N. Canada (Macoun); 
 Barton, Vt. (Robbins); Granby, Mass. (Tuckerman); Pleasant 
 Pond, Wenham, Mass. (Morong); Worcester and Natick, Mass. 
 (Morong); Pine Plains, N. Y. (Hoysradt); Spencer, N. Y. (Dud- 
 ley); Easton and Susquehanna River, Pa. (Porter); Lake Superior 
 (Robbins); Vermilion Lake, Minn. (L. H. Bailey); Sherburne 
 Geyer Basin, Wyoming (Clifford Richardson). July-August 
 (Plate XLVIII.) 
 
 25. POTAMOGETON MAJOR (Fries) Morong. 
 
 P. pusilllns L. var. major > Fries, Nov. 48 (1828).' 
 
 P. Friesii, Ruprecht in Beit. Pf. de Russ. R. iv. 43 (1845). 
 
 P. compresses, Sm. Eng. Bot. iii. t. 418 (1794). Reich. Ic. Fl. 
 
 Germ. vii. 15 (1845), not L. 
 
 The name compresus, which is used by some authors must be 
 discarded, because it is applied by Linnaeus himself to several 
 species. P, mncronatus, Schrad., is also uncertain, according to 
 Mr. Bennett, who has carefully studied the synonymy of this 
 species. (See Journ. Bot. May, 1891, p. 150). Fries' varietal 
 name, so far as I can see, is the earliest name applied to it on which 
 we can depend. 
 
 Stems compressed, 2-4 feet high, branching, Leaves I ^-2 */ 
 inches long, about I line wide, shortly acute or obtuse and cuspi- 
 date, usually 5 -nerved, but rarely 7-nerved, biglandular at base, 
 the glands small, often dull. Intermediate forms between this and 
 P.pusillus often occur in this country in which most of the leaves
 
 42 
 
 are 3-nerved or 5 -nerved at the base only. Stipules white, hyaline, 
 finely nerved, obtuse or acute, 6-12 lines long. Peduncles i-i l / 2 
 inches long, often thicker than the stem and sometimes thickening 
 upwards. Spikes when developed interrupted. Fruit quite simi- 
 lar to that of P. pusillus, but I find it always with a recurved style, 
 generally with a shallow pit on the sides and with the apex of the 
 embryo pointing almost directly towards the basal end. The pro- 
 pagating buds are similar to those of P. pusillus, but not so 
 common. 
 
 This species may generally be distinguished from pusillus in 
 its various forms by its larger leaves, larger and more flattened 
 stems and its more elongated and less branching habit, but the 
 two run together so closely that at times it is difficult to separate 
 them. It is considered by some authors as intermediate between 
 P. pusillus and P. obtusifolius, and when not in fruit it may be con- 
 founded with the latter, but as a rule the glands are smaller and 
 duller in tint than in that, and the leaves shorter. P. obtusifolius, 
 too, is much more bushy in habit, sometimes even spreading out 
 in fan-shape, and it is extremely rare that its leaves have more 
 than 3 nerves. 
 
 The species rare in the United States. New Brunswick, On- 
 tario and British Columbia (Macoun); Lake Champlain, Vt. 
 (Faxon) ; Lake Seneca, N. Y., abundant (Morong) ; Wisconsin 
 (Lapham); Michigan (Hill); Minnesota (Cratty). July-Septem- 
 ber. (Plate XLIX. A leaf magnified is shown on the left.) 
 
 26. POTAMOGETON RUTiLUS, Wolfg. in R. and S. Mant. iii. 362 
 
 (1827). 
 P. caspitosus, Nolte, fide Reich. Ic. vii. 15. 
 
 Stems very slender, 8 to 24 inches in height, compressed; roots 
 finely fibrous, sending up many stems, but each stem simple or 
 nearly so. I find them occasionally rising from a bit of stem or 
 hybernaculum, showing that the species is sometimes, at least, 
 propagated in this way, but usually without propagating buds. 
 Leaves I to I y 2 inches long and ^ to y 2 a line broad, acute or 
 acuminate, strict, nearly erect, 3-5 nerved, revolute, nerves promi- 
 nent beneath, the midrib compound, especially at the base, where 
 it often divides into 2 and even 4 strongly marked nerves, often
 
 43 
 
 biglandular at base and bright green in color. Stipules acute, 6- 
 10 lines long, often longer than the internodes and hiding the 
 bases of the leaves above, persistent, becoming white and fibrous 
 with age. Peduncles 6-18 lines long, scarcely thicker than the 
 stems. Spikes 3-5 lines long, usually continuous, but sometimes 
 interrupted. Fruit obliquely obovate, ^-i line long by ^-% 
 line wide, keels obscure, or the back showing only 2 small grooves; 
 face obtusely angled towards the base; apex of drupe sloping into 
 a short, facial, recurved style; embryo circle not complete, the apex 
 pointing a little inside of the basal end. Resembling pusillns, 
 especially those occasional forms of that species which have acute 
 and somewhat revolute leaves; but its strict, almost or quite erect 
 leaves with long very sharp acuminate points, prominent nerves, 
 and long, persistent, acute stipules well distinguish it. 
 
 A rare species in this country. Anticosti, at the mouth of the 
 Nipigon River, near Red Rock, Lake Superior and James Bay, 
 Canada (Macoun). Found by Prof. L. H. Bailey in flower July 24, 
 1886, in Vermilion Lake, Minn., (no. B. 394). (Plate L.) 
 
 27. POTAMOGETON VASEYi, Robbins, in A. Gray. Man. Ed. 5, 485 
 
 (1867). 
 
 Bearing floating leaves on the fertile stems only. Very deli- 
 cate, stems filiform, widely branching from below and with many 
 short lateral branches above, i-i^ feet in height. The emersed 
 fertile forms in shallow water, near shore, and the more common 
 sterile submerged forms in water from 6 to 8 feet in depth. Float- 
 ing leaves coriaceous, in 1-4 opposite pairs at the top of the stem, 
 the blades obovate, 4-5 lines long by 2-3 lines wide, with 5-9 
 nerves deeply impressed beneath, sloping at base into petioles 3-4 
 lines long. Submerged leaves almost capillary, nerveless or i- 
 nerved, tapering to the fineness of a hair, i-i^ inches in length. 
 The leaves frequently biglandular at base. Stipules white, delicate, 
 many nerved, acute or obtuse, 2-3 lines long. Peduncles 3-6 
 inches long, spreading or recurved, thickening in fruit. Spikes 
 2-3 lines long, often interrupted. Fruit roundish-obovate, about i 
 line long and nearly as broad, 3-keeled, middle keel rounded ; face 
 arched above and incurved below, tipped with a rather long 
 straight or recurved style; sides even or impressed with a shallow
 
 44 
 
 pit. The spikes ripen from 2 to 6 fruit, most of the flowers being 
 abortive. This species, especially in the submerged plant, is fur- 
 nished with delicate reproductive buds which are formed at the 
 ends of short lateral branches and by which it seems to be mainly 
 propagated. The internodes are usually long and naked. 
 Var. LATIFOLIUS, Morong. 
 
 A rare form with submerged leaves ^-^4 of a line wide, 
 abruptly acute and i-3-nerved. The glands more conspicuous 
 than in the type. This was collected by Dr. Beardsley at Paines- 
 ville, Ohio. 
 
 A rare endemic species confined to Canada and the Northern 
 United States. 
 
 The original plant was collected by Dr. George Vasey near 
 Ringwood, Ohio. It has since been found at Ottawa (Fletcher), 
 and on the Great Plains, Canada (Macoun) ; Barnet, Vt. (Dr. 
 Blanchard); Lake Saltonstall, Conn. (O. D. Allen); Spot Pond, 
 Stoneham, Mass., Lake Quinsigamond, Worcester, Mass, and 
 Greenwood Lake, N. Y. (Morong). (Plate LI.) 
 
 28. POTAMOGETOM LATERALis, Morong, Bot. Gaz. v. 51 (1880). 
 
 Stems filiform, much-branched, internodes usually long and 
 naked. Floating leaves coriaceous, elliptical, obtuse at the apex 
 and sloping at base into petioles 3-10 lines long, blades 4 or 5 
 lines long by 1-2 lines broad, with 5-7 nerves deeply impressed 
 beneath, usually in 1-3 opposite pairs which stand at right angles 
 to the stem, found only on sterile shoots. Submerged leaves very 
 narrow, linear, acute, 1-3 inches long and y^-Y* lme wide, 1-3- 
 nerved, the lateral nerves very delicate and obscure, the midrib 
 prominent and often with fine veins or cellular reticulations on 
 each side of it, biglandular at base, but the glands few, small 
 and often obsolete. Stipules small, hyaline, many-nerved, obtuse, 
 deciduous. Peduncles as well as the floating leaves with a pecu- 
 liar lateral appearance, widely spreading at maturity, sometimes 
 even recurved, thickened when in fruit, 4-15 lines in length. 
 Spikes capitate or often interrupted, 3-4-flowered. Fruit obliquely 
 obovate, about i line long by ^ line broad, lenticular, the back 
 much curved and 2-grooved, the face arched and surmounted by 
 the nearly sessile stigma ; embryo oval in its curve, the apex
 
 45 
 
 nearly touching the point of the base. The plant is scantily fur- 
 nished with reproductive buds like those of P. pusillus. Proliferous 
 shoots at the summit of the stem and on the upper branches, 
 above the floating leaves, appear late in the season just as the 
 plants are beginning to decay, a very peculiar habit. 
 
 In slowly-moving water, 3-4 feet deep, in dense masses, 
 Charles River, Dedham, Mass. (Faxon, Morong) ; Salisbury, 
 Conn. (Robbins); Hemlock Lake, Livingstone Co. N. Y., and 
 Bear Lake, Mich. (Hill). July, August. (Plate LII. Sterile and 
 fertile branches.) 
 
 29. POTAMOGETON PUSILLUS, L. Sp. PI. I 2J (l/53). 
 
 A variable species with filiform, branching stems from 6 inches 
 to 2 feet in height. Leaves all submerged, linear, obtuse and 
 mucronate or acute at the apex, i-3-nerved, biglandular at base, 
 rarely glandless, 1-3 inches long and ^-^ line broad. The typ- 
 ical form (var. vulgaris. Fries. Nov. p. 49), has leaves 3-nerved, 
 from a little less than ^ to ^ line broad, obtuse or shortly acute, 
 and not unfrequently cellular-reticulate between the midrib and 
 the lateral nerves. The leaves are sometimes revolute and slightly 
 ridged in the middle, resembling in this respect those of P. rutilus. 
 Another common form has the leaves about ^ line wide, almost 
 setaceous, i-3-nerved, the lateral nerves obscure or obsolete, acute 
 (var. tenutssimtfs, M. and K. Deut. Fl. i. 857. P. gracilis, Fries, 
 Nov. p. 50). 
 
 Both of these forms are occasionally provided with reproduc- 
 tive buds. 
 
 Stipules short, hyaline, obtuse, when enclosing the bud boat- 
 shaped. Peduncles vary greatly in length, generally from 3 to 9 
 lines long, but occasionally elongated from I to 3 inches, and 
 sometimes thickened ' in fruit. Spikes about as often interrupted 
 as capitate in all the forms, 3-io-flowered. Fruit obliquely ellip- 
 tical, 2^-1 line long and ^-^ line wide, curved and 2-grooved 
 on the back, or sometimes with 3 distinct keels; face slightly 
 arched or often with a projecting curve above and an inward curve 
 below, beaked by a short, straight or recurved style ; apex of the 
 embryo slightly incurved and pointing obliquely downwards.
 
 46 
 
 Var. PANORMITANUS (Biv). Morong. 
 
 P. Panormitanits, Biv. Sic. PI. (1806-7). 
 
 Uppermost leaves subcoriaceous, spatulate, opposite, divaricate, 
 in i or 2 pairs, 3-5 -nerved, with cross-veins and often covered 
 with a chain-like areolation, 4-5 lines long, sloping at base into a 
 broad petiole as long as the blade. Collected in pools at Ottawa, 
 Canada, by James Fletcher, July 1882. 
 Var. POLYPHYLLUS, Morong, Bot. Gaz. v. 51 (1880). 
 
 A dwarf form 3-5 inches high, divaricately branching from the 
 base, and very leafy throughout. Leaves very obtuse, 3-nerved. 
 Not flowering, but abundantly provided with propagating buds 
 which are found on the thickened and hardened ends of the 
 branches, and closely invested by imbricated leaves. In a shallow 
 pool, with oozy bottom, some distance underwater, South Natick, 
 Mass. (Morong); Fresh Pond, Cambridge, Mass. (Faxon). 
 Var. ELONGATUS, Ar. Bennett. Macoun's Cat. Can. PI. Pt. 5, 371 
 
 (1890). 
 
 I have not seen a specimen of this form, but it is thus de- 
 scribed by Mr. Bennett in Jour. Bot. for May, 1891, p. 151: 
 " This differs from pusillus by the larger size of all its parts and very 
 long internodes; leaves remarkably elongated ; peduncles stout and 
 long ; spikes much longer ; leaves often quite acute ; flowers larger 
 in all their parts. Habit of rutilus, Wolfg., and so named in speci- 
 mens from Hungary in Herb. Mus. Brit." Coll. Macoun, Spallum- 
 sheen River, at and above Enderby, B. C. 
 
 Var. STURROCKII, Ar. Bennett, in Hook. Stud. Fl. 435 (1884). 
 
 This form occurs rather rarely in the United States. It is dis- 
 tinguished by its delicate, bright green, pellucid leaves, which are 
 1-3 inches long, obtuse or often apiculate at the apex and ^-^ 
 line broad. Mr. Bennett states that the British specimens are 
 sometimes 5 -nerved, but I have seen none with more than 3 
 nerves. There is often, however, at least in American specimens, 
 a finely-reticulated space on each side of the midrib. The fruit, 
 according to Mr. Bennett, is much smaller than in the type, with 
 a short beak. This I have not seen. 
 
 P. pusillus seems to be the central species of a group, being 
 approached on the one hand by P. lateralis, and on the other by
 
 47 
 
 gemmipants and major, all together forming a well-marked aggre- 
 gate. 
 
 A widely-diffused species, common in Canada from New Bruns- 
 wick to British Columbia, New England to Louisiana and Texas, 
 west to Oregon and California. San Luis Potosi, Mexico, Schaff- 
 ner, No. 533. Europe. Pools and ditches. July, August. 
 (Plate LIII.) 
 
 30. POTAMOGETON GEMMiPARUS (Robbins) Morong, Bot. Gaz. v. 
 
 51 (1880). 
 P. pusillus L., var. ? gemmiparus, Robbins in A. Gray, Man. Ed. 
 
 5,489(1867). 
 
 Stems filiform, branching, terete, greatly varying in height, 
 rising from 5 inches to 4 feet, according to the depth of water in 
 which it grows ; the internodes below, especially in deep water 
 forms, as much as 5 inches in length. Leaves capillary, sometimes 
 not as broad as the stem, often with no perceptible midrib, taper- 
 ing to the finest point, 1-3 inches long, biglandular at base; 
 stipules 1/^-1 inch in length, acute or obtuse, mostly deciduous. 
 Rarely flowering, the spikes interrupted, 3-6-flowered ; peduncles 
 filiform, sometimes a little thickened, ^-2 inches long. Fruit ex- 
 ceedingly rare, and in size and shape like that of P. pusillus, except 
 that it is flatter and somewhat impressed on the sides. It is com- 
 monly propagated by gemmae, which are abundant. The leaves 
 and stems are often alike in thickness, so that the plant seems to 
 consist of threads, and this with the long, naked internodes, ren- 
 ders its appearance very peculiar. 
 
 A few specimens in fruit were obtained at Amherst, Mass, by 
 Prof. H. G. Jesup in 1874, and by him sent to Dr. Robbins, who 
 thereupon substituted in his herbarium the name here adopted. It 
 was first found by Dr. Robbins in the Blackstone Valley from Wor- 
 cester, Mass, to Providence, R. I., and has since been collected by 
 myself in the Charles River, at South Natick, Mass. Also by Mr. 
 J. F. Collins, in Central Pond, R. I. Pools and slow moving 
 streams. August, September. (Plate LIV. The rare fruiting 
 form is seen on the right.)
 
 48 
 
 31. POTAMOGETON DIVERSIFOLIUS, Raf. Med. RepOS. 2d Hex. V. 
 
 354(1808). 
 
 P. hybridus, MX. Fl. i. 101 (1803). 
 
 We are obliged to drop the name of Michaux, because it had 
 been previously employed by Thuillier for P. heterophyllus (Fl. Par. 
 1 790), and that of Rafinesque comes next in date. 
 
 Stems flattened, sometimes terete, much-branched, but never 
 recurved as sometimes occurs in P. Spirillus. Floating leaves 
 coriaceous, the largest 12 lines long by 6 lines wide, oval, ellipti- 
 cal and obtuse or lance-oblong and acute. Petioles generally 
 shorter, but sometimes longer than the blades, filiform or dilated. 
 Submerged leaves setaceous, flat, in the typical form seldom over 
 y^ line in width, 1-3 inches long, I -nerved, often with many fine 
 lines and long reticulations on each side of the midrib. Stipules 
 obtuse or truncate, hyaline, 3-5 lines in length, on the floating leaves 
 free, on the submerged leaves commonly adnate to the petiole, but 
 often free. Emersed peduncles 3-7 lines long and thickened upwards. 
 Submerged peduncles 2-3 lines long, as long as the spikes, clavate, 
 often recurved. Emersed spikes 3-5 lines long, occasionally inter- 
 rupted. Fruit rarely over y 2 line long and nearly as broad, 3- 
 keeled, middle keel narrowly winged, usually with 7 or 8 knob-like 
 teeth on the margin, the lateral keels sharp or sometimes rounded ; 
 style quite apparent as a short point, apical ; embryo coiled i y z 
 times. This and the following species are much alike in general 
 appearance and often confounded. In well-marked forms, how.- 
 ever, the two may readily be distinguished not only by the differ- 
 ence in the submerged peduncles, but by the width of the 
 submerged leaves, those of P. diversifolius being capillary or 
 setaceous and only i -nerved. Sometimes the leaves are broader, 
 and then the chief mark of distinction lies in the submerged pe- 
 duncles. Both species are really intermediate between the section 
 of Potamogetons with free stipules and that with adnate stipules, 
 as in the uppermost leaves the stipules are free, and adnate only 
 in the lower. In extent of adnation this species approaches the 
 former and the following species the latter. 
 Var. MULTI-DENTICULATUS, Morong, n. var. 
 
 Varies from the type in the numerous teeth on the fruit, as 
 many as 12 being sometimes found on the middle keel, and each
 
 49 
 
 lateral keel with 6 or 8 more. Frequently the teeth are bristle- 
 like, and sometimes 2-pronged. The submerged leaves are from 
 ]/ to y 2 line in width, rarely as narrow as in the type. The most 
 distinctly-marked specimens of this form were collected by Mr. C. 
 F. Parker in a pond at Rehoboth City, Delaware, August 7, 1878. 
 I have since noted the following localities for it : Noank, Conn. 
 (Morong) ; ponds on the Susquehanna land at Easton, Pa.- (Por- 
 ter) ; Florida (Curtiss, Regel, No. 72) ; Lower Louisiana (Langlois). 
 Var. TRICHOPHYLLUS, Morong, n. var. 
 
 About 6 inches in height, without floating leaves, the sub- 
 merged leaves as fine as floss silk, and entirely destitute of nerves. 
 
 Coll. N. L. Britton, Lake Marcia, Sussex Co. New Jersey. 
 
 The species in pools and ponds from New England to Nebraska, 
 and south to Florida and Texas, San Luis Potosi, Mexico (Schaff- 
 ner No. 534 and Parry and Palmer No. 856). Cuba (Wright). It 
 ranges farther to the south than Spirillns and not so far north. It 
 occurs in Maine, but Prof. Macoun expresses a doubt whether the 
 Canadian forms attributed to this species are not Spirillus and such 
 as I have seen from Canada confirm his opinion. (Plate LV.) 
 
 32. POTAMOGETON SPIRILLUS, Tuckerm. Am. Jour. Sci. and Arts, 
 
 2d series, vi. 228 (1848). 
 P. Zctterstcdtii, Wallm. ap. Sch. et Mohl. Bot. Zeit. i. 256 (1843)? 
 
 (fide Bennett Jour. Bot. xxviii. 298.) 
 
 Stems compressed, much branched, the branches often short 
 and recurved, 6-20 inches high. Floating leaves coriaceous, ob- 
 tuse, usually opposite and in several pairs towards the summit of 
 the stem, oval or elliptical, varying to lanceolate, the largest about 
 12 lines long by 6 lines wide, sometimes narrow-oblong, deeply 
 impressed beneath by 5-i3-nerves. Petiole commonly about 
 equal to the blade, but sometimes only ^ or y 2 its length, some- 
 what dilated. Submerged leaves linear, obtuse or abruptly acute, 
 1^-2 lines long and Y^-^/2 line wide, uppermost sometimes I line 
 wide, usually 3-nerved,the lateral nerves near the margin, rarely with 
 5 very delicate nerves, often with irregular reticulated spaces on 
 each side of the midrib. Stipules, like those of the preceding 
 species, on the uppermost floating leaves entirely free, on the lower 
 adnate to the petiole near the base, on the submerged adnate to
 
 50 
 
 the leaf for about one-half their length. In dried specimens, the 
 stipules appear free from all the floating leaves. Emersed pe- 
 duncles usually similar to those of the preceding species. Sub- 
 merged peduncles usually wanting, or at most, hardly I line long. 
 Spikes above water 3-5 lines long, continuous, while the lower 
 are mostly sessile in the axis of branches, capitate aud ripening 
 from i to 4 fruit. Fruit cochleate, very thin, nearly fleshless, 
 roundish, about $ line long and nearly as broad, flat and deeply 
 impressed on the sides, 3-keeled on the back, middle keel winged, 
 wing broad and with 4 or 5 large teeth or very narrow and with- 
 out teeth, the lateral keels rounded ; style usually marked on the 
 dried fruit only by a slight projection or a scar ; embryo commonly 
 coiled about I ^ turns. The spiral markings of the embryo are 
 distinctly seen in the dried fruit, and are a very distinctive feature, 
 strongly reminding one of a small snail shell. 
 
 Pools, ditches and ponds. Nova Scotia (Mrs. E. G. Britton) ; 
 New Brunswick, Quebec and Ontario (Macoun). Common in 
 New England, and west to Minnesota, Missouri (Blankenship) 
 and Nebraska, south to Pennsylvania and Virginia. (Plate LVI.) 
 33. POTAMOGETON FiLiFORMis, Pers. Syn. i. 152 (i8os). 
 P. marinus of authors, not L. Herb. 
 
 Stems from a running rootstock, slender, 3-20 feet in height, 
 filiform above, stout and thick towards the base. Flowers on 
 long, often drooping peduncles, the longest measuring 6 to 8 
 inches, 2-4 in a whorl and the whorls ]^-i inch apart. Leaves 
 numerous, 2-10 inches long and from ^ to ^ line, very rarely ^ 
 line, broad, i -nerved, with a few cross nerves. Sheaths about i 
 line long, and the free part of the stipule */ 2 inch more, scarious on 
 the edges. From 3 to 12 drupes are ripened in a verticil. Fruit 
 \-i l / 2 lines long and about ^ line wide; sides even ; back not 
 keeled in fresh specimens and scarcely so in the dry ; face nearly 
 straight or obtusely angled near the top ; stigma nearly or quite 
 sessile, remaining on the dry fruit as a broad truncate projection, 
 apical or subapical ; embryo circle incomplete, the apex pointing 
 slightly inside of the basal end. 
 
 Var. MACOUNII, Morong, Macoun's Cat. Can. PL pt. 4. 88 (1888.) 
 
 Quite a distinct form with leaves 1-3 inches long, the largest 
 
 l / 2 a line or a little more in width, obtuse, stiff, with a strong mid-
 
 51 
 
 rib and raised or slightly revolute margins. Fruit small, rarely 
 more than a line in length and ^ of a line in breadth. Peduncles 
 short, not more than 8 or 10 lines long at the most. This form 
 commonly has a compact, bushy habit which is quite noticeable. 
 Occurs in brackish and salt lakes of the prairie region, in Old 
 Wives' Lakes and Crawling Valley, south of the Hand Hills, 
 Alberta, Canada (Macoun). This approaches : 
 Var. occidentalis, Robbins, Bot. King's Ex. 339 (1871). 
 
 This as described by Robbins has some of the leaves similar to 
 those of the preceding variety, but the peduncles often as much 
 as 6 inches long, the fruit roundish-obovate, and the sides of the 
 nutlet made " uneven by a central elevation partially surrounded 
 by a shallow depression which is marginned by the raised lateral 
 keel." Ruby Lake, Nevada, 6,000 feet alt., (Watson); Shoshone 
 Geyer Basin, Wyoming (Clifford Richardson). 
 
 The species is rare in the United States, and was first detected 
 by myself in the rapids above Niagara Falls in 1875, and since in 
 similar rapids at Sault Ste. Marie, Mich. It is abundant in Seneca 
 Lake, N. Y., and Mr. Hill has obtained it in Hemlock Lake, 
 Western New York and Frankfort, Mich. It is more common in 
 Canada, having been obtained by Prof. Macoun in brackish marshes 
 on the sea coast at the Island of Anticosti, and in fresh water lakes 
 and creeks in the Northeast territory, Manitoba and British Colum- 
 bia. August. (Plate LVII.) 
 
 34- POTAMOGETON PECTINATUS, L. Sp. PI. 127 ( 1 7S3}- 
 
 Stems slender, from a running rootstock, much branched, the 
 branches repeatedly forking, I to 3 feet in height, usually much 
 stouter below. Leaves setaceous, attenuate to the apex, I -nerved, 
 1-6 inches long, often capillary and without nerves. Gigantic 
 forms were collected by Prof. W. R. Dudley in Lake Cayuga, from 
 1 8 to 20 feet in length, and with leaves even 10 inches long. The 
 form scoparius, Wallr., found in this country as well as in England, 
 has numerous hair-like fasciculated leaves, very long and broom- 
 like in appearance, whence the name. Stipules with sheaths 
 which are white and scarious on the edges, */-! inch 
 long, and half as much free. Peduncles filiform, 2 to 12 inches 
 long, the flowers in approximate or distant verticils, 2 to 4 flowers
 
 52 
 
 ripening 2 to 8 seeds, in a verticil. Fruit roundish obovate or 
 obliquely obovate, with a thick hard shell, I y&-2 lines long and 
 i-i y lines wide, without a middle keel, but with obscure lateral 
 ridges on the back, plump on the sides, and curved, occasionally 
 a little angled on the face; style distinct, straight or recurved, 
 facial ; embryo apex nearly touching and pointing directly towards 
 the basal end. In American plants, the keels are generally ob- 
 scure and often obsolete, and the fruit more nearly approaches 
 that oi filifonnis in size. 
 
 This species is frequently propagated by root tubercles which 
 are nearly as large as peas and lie imbedded in the mud through 
 the winter. In this state they are eaten by wild fowl, and the 
 crops of these birds are often filled with them. 
 
 P. pectinatus and P. filifonnis are often confounded, and in 
 the absence of fruit it is impossible in all cases to make sure of 
 the species. As a general rule P. filifonnis is a smaller plant. 
 In regard to the fruit, that of P. pectinatus may always be known 
 from filifonnis by its distinct and often recurved style, and usually 
 it is larger. Both species occur in brackish water, sometimes in 
 tidal and salt w r ater, and also veiy extensively in fresh water. 
 
 Ponds and rivers. Widely distributed in Canada from Cape 
 Breton to British Columbia and northwards (Macoun). In the 
 United States it ranges from New England to Florida and Texas, and 
 across the continent to Oregon and California. Lower California 
 (Orcutt, Palmer). Southern Mexico (Helmsley). Cuba (Wright). 
 A world-wide species, occurring in Europe, Australia, Africa and 
 Asia. (Plate LVIII.) 
 
 35. POTAMOGETON LATiFOLius (Robbins) Morong. 
 
 P. pectinatus, var. (?) latifolius, Robbins, Bot. King's Ex. 338 
 
 (1871). 
 
 Stem stout, white, branching, 2-3 feet high. Leaves numer- 
 ous, flat, 1-3 inches long and 1-2 lines broad, 3-5 nerved, reticu- 
 late with many cross veins, obtuse or abruptly apiculate, the nar- 
 rower ones acute. The part of the stipule adnate to the leaf, broad, 
 many-nerved, scarious-margined, y 2 -\ inch long, the free portion 
 shorter. Peduncles 1-3 inches long. Spikes interrupted. Mature 
 fruit much like those of pectinatus, while the foliage differs greatly.
 
 53 
 
 Fruit about 2 lines long by \y 2 lines wide; back usually without 
 a keel, the lateral ridges rounded; face gibbous at the top; style 
 facial, rather long, erect or slightly recurved; embryo apex point- 
 ing slightly inside of the basal end. Often in the fruit the curve 
 of the back rises at the top almost as high as the style, making 
 that appear as if on the face, a peculiarity which occurs sometimes 
 in pcctinatns also. It is a question whether this form is the same 
 as the broad-leaved forms of flabcllatus, but it differs from that 
 species not only in fruit characters, but in having many short 
 lateral branches, shorter and more obtuse leaves, and a stouter 
 and stricter stem. 
 
 The plant described by Robbins was collected in the "running 
 brackish waters of Humboldt River below Humboldt Lake," Ne- 
 vada. A fine specimen is in the Herb, of Mr. I. C. Martindale, of 
 Camden, New Jersey, collected by Mrs. R. M. Austin in Goose 
 Lake, Northeastern California, in Sept. 1884. The fruit here de- 
 scribed is taken from that specimen. (Plate LIX.) 
 
 36. POTAMOGETON INTERRUPTUS, Kitaibel; Schultes, CEst. Fl. Ed. 
 
 2, 328 (1814), fide Ar. Bennett. 
 P.flabdlatus, Babington, Man. Bot. Ed. 3, 343 (1851). 
 
 From a running rootstock which often springs from a small 
 tuber. Stems stout, branching, 2-3 feet in height, the branches 
 spreading like a fan. Leaves linear, obtuse or acute, 3-5 inches 
 long, i line or a little more in width, 3-5 -nerved, with many trans- 
 verse veins.* Narrow, I -nerved leaves occur on some plants, and 
 these are acuminate, much like those of P. pectinatus. Stipule on 
 the adnate part ^-i inch long, without scarious edges, or nar- 
 rowly scarious, the free part shorter and scarious, obtuse. Pe- 
 duncles 1-2 inches long. Spikes slightly interrupted. 
 
 Our United States plants have never been observed in fruit, 
 but I am able to give the fruit characters from specimens kindly 
 
 *It should be noted that Mr. Fryer regards these broad leaves as belonging mostly 
 to sterile or autumnal shoots. Normally, as he describes the leaves, they are narrow 
 or setaceous like those of pectinatus. The chief difference between the species and 
 pectinatus, in his opinion, lies in the fruit. But as these broad leaves are the only 
 ones so far found in the United States, and as they are the kind originally attributed to 
 the species by Prof. Babington, I can only pay regard to their in this account of our 
 species.
 
 54 
 
 furnished by Mr. Fryer and collected by him in Cambridgeshire, 
 England, where the plant is common. Fruit broadly obliquely 
 obovate, obtuse at base, the largest 2 lines long by i^ lines wide, 
 prominently keeled and with rounded lateral ridges on the back ; 
 face nearly or quite straight, sometimes gibbous at the top ; style 
 facial, erect; embryo outline obovate, the apex pointing slightly 
 inside of the basal end. The shell of the drupe is exceedingly 
 thick and quite hard. 
 
 First found by Mr. E. J. Hill in ponds at Manistee, Mich., and 
 subsequently collected by myself in the same locality. Also col- 
 lected by Mr. Hill in the Channel Islands, St. Mary's River, Mich. 
 Mr. Hill takes especial notice of the tubers by which this species 
 is frequently propagated. This method of propagation it has in 
 common with P. pectinatus, to which it is closely allied. (Plate 
 LX.) 
 
 37. POTAMOGETON RoBBiNsn, Oakes, Hovey's Mag. May, 1841, 
 
 p. 2. 
 
 Stems stout, widely branching, 2-4 feet high, from running 
 rootstocks sometimes 10 or 12 inches long. Leaves 3-5 inches 
 long, 2-3 lines wide, acute, finely many-nerved, crowded in 2 
 ranks, minutely serrulate under the lens, auriculate at the point of 
 attachment with the stipule. Stipules with the adnate portion and 
 sheathing base of the leaf about y 2 an inch long, the free part from 
 y 2 to I inch, acute, persistent, white, membranous, mostly lacerate. 
 Peduncles 1-3 inches long, the infloresence frequently much 
 branched and bearing from 5 to 20 peduncles. Spikes interrupted, 
 ^-^ inch long, flowering under water, but the rarest of all our 
 North American species to form fruit. It is propagated very ex- 
 tensively by fragments of the stems, which throw out many root- 
 lets from every joint. I have seen such rootlets from 6 to 10 
 inches long on floating specimens, and even a stem standing up- 
 side down in the mud and growing apparently as well as in the 
 normal position. Very rarely in years when the waters are low, 
 the flowering spikes rise above the surface and perfect a few fruit. 
 Dr. Robbins never saw but one fruit, which was collected many 
 years ago in Oregon by Hall, and this was split in two, Prof. D. C. 
 Eaton taking one-half and Dr. Robbins the other. In the year
 
 55 
 
 1 880 Mr. E. Faxon had the good fortune to secure a few fruiting 
 specimens in Jamaica Pond, Mass. Besides them I have never 
 known another instance, although the plant is very prolific in the 
 localities where it occurs, sometimes densely covering the bottoms 
 of ponds for acres. Mature fruit obovate, about 2 lines long by 
 I y 2 lines wide, 3-keeled on the back, the middle keel sharp and 
 prominent, the laterals rounded ; face arched ; sides with a shallow 
 depression which runs into the face below the arch ; style sub- 
 apical, thick, slightly recurved, obliquely truncate; apex of the 
 embryo pointing slightly inside of the basal end. 
 
 So far as known, confined to the northern part of North 
 America. New Brunswick, Ontario, Lake Superior (Macoun) ; 
 New England to Northern New Jersey, and westward to Oregon 
 (Hall, Wilkes' Exploring Expedition). (Plate LXI.) 
 
 5. RUPPIA, L. Sp. PI. 127 (1753). 
 
 Stems capillary, widely branched. Leaves very slender, alter- 
 nate, I -nerved, tapering to an acuminate point, with a membranous 
 sheath at the base. Flowers on a capillary, spadix-like peduncle, 
 naked, perfect, consisting of two sessile anthers, each with 2 large, 
 separate cells, attached by the back to the peduncle, having be- 
 tween them several pistillate flowers, in 2 sets, on opposite sides 
 of the rachis, the whole at first enclosed in the sheathing base of 
 the leaf; stigmas sessile, peltate. In the development, the stami- 
 nate flowers drop off, and the peduncle elongates, bearing the 
 pistillate flowers in two clusters at the end. The flowers are ferti- 
 lized above water, after which the peduncles coil up and are drawn 
 beneath the surface. Fruit a small, obliquely pointed drupe, several 
 in each cluster, pedicelled ; embryo oval, the cotyledonary end in- 
 flexed, and both that and the radicle immersed. 
 
 Half a dozen or more species have been enumerated, but prob- 
 ably all may be reduced to two or three. In salt, brackish and 
 fresh waters throughout the world. 
 
 i. RUPPIA MARITIMA, L. Sp. PI. 127 (1753). 
 
 Stems often whitish, 2 or 3 feet high, the nodes irregular, 
 naked, 1-3 inches long. Leaves 1-3 inches in length and ^ line or 
 less in breadth ; sheaths membranous, 3-4 lines long and with a 
 minute ligule or short free tip at the top. In fruit the peduncles
 
 56 
 
 are greatly elongated, sometimes as much as 1 2 inches or even 
 more ; pedicels 4-6 in a cluster, y 2 -i l /2 inches in length. Drupes 
 with a dark hard shell, about I line long, ovoid, often oblique or 
 gibbous at base, pointed with the long style. The drupes vary a 
 good deal in shape, usually simply conical with a short gibbous 
 swelling at the base, sometimes with a strong spur-like projection 
 and a curved outline, as in the form known in Europe as R. ros- 
 tellata, Koch, which does not, however, differ otherwise from the 
 type. Specimens with fruit of this shape are sent from Oregon 
 by Mr. Howell. Forms with fruit nearly destitute of peduncles 
 and pedicels, and broad strongly marked sheaths, similar in these 
 respects to R. bracliypiis, Gay, occur at Wood's Roll, Mass., and 
 at other places along the Atlantic coast. (Plate LXII.) 
 
 2. RUPPIA OCCIDENTALIS, S. Watson, Proc. Am. Acad. Sept. 25, 
 
 1890, p. 138. 
 R. lacnstris, Macoun, Cat. Can. PL Pt. 5. 372, Nov. 1890. 
 
 A stoutish-stemmed plant 1-2 feet high, the branches forking 
 in fan shape. Leaves 3-8 inches long, with large sheaths ^-i^ 
 inches in length. Branches and leaves often thickly clustered at 
 the nodes, the sheaths overlapping each other. Drupes large, 
 I y 2 -2 lines long, of a thick pear shape, on pedicels ^-i inch long. 
 Prof. Macoun states that the peduncles are bright red when fresh. 
 
 Coll. by Macoun in a saline pond at Kamloops, B. Columbia. 
 Also collected by H. J. Webber in a saline region at Alliance, 
 Box Butte Co., Nebraska. Mr. Webber writes that he found pe- 
 duncles nearly 2 feet in length. (Plate LXII I.) 
 
 6. ZANNICHELLIA, L. Sp. PL 969 (1753). 
 Stems, flowers and leaf buds all at first enclosed in a 
 hyaline envelope, a sort of spathe, corresponding to the stipule of 
 Potawcgoton, rising from a node. Staminate and pistillate flowers 
 in the same axil ; the stamen solitary, 2-celled, on a short pedicel- 
 like filament ; pistillate 2-5 or more in a special envelope of their 
 own. The stamen is said to be 4-celled occasionally, but I never 
 could find more than 2 cells. Ovary a flask-shaped body, stipulate 
 at base, tapering into a short style, with a broad, hyaline stigma 
 which is somewhat cup-shaped, and has irregular, angled or den- 
 tate edges. Sometimes the whole cluster of flowers is on a stipe
 
 57 
 
 or peduncle. In fruit the stipe and style lengthen, and the ovary 
 is prolonged iuto a flattish, falcate nutlet, ribbed or sometimes 
 toothed on the back. Seeds corresponding to fruit ; the embryo 
 bent and coiled at the cotyledonary end. 
 
 Found in all parts of the world. Haifa dozen different species 
 have been described by authors, but most of them can be reduced 
 to the following species, and probably not more than 2 or 3 species 
 exist. 
 
 i. ZANNICHELLIA PALUSTRIS L, Sp. PI. 969 (1753). 
 
 Flowering and ripening its fruit under water. Stems capillary, 
 sparsely branched, from a creeping rhizome and fibrous roots, 1-2 
 feet high. Leaves 1-3 inches long, */ line or less in breadth, 
 acute, thin, I -nerved and with a few delicate cross nerves. Spathe 
 or stipule separating from the leaves and fruit at maturity, per- 
 sistent. Fruit 2-4, sometimes 6, in a cluster, falcate, 1-2 lines 
 long, variously disposed, sometimes sessile, sometimes, as in forma 
 pediccllata, J. Gay, each on a pedicel, or, as in forma pedunculata 
 A. Gray, the whole cluster on a short peduncle. The fruit is gen- 
 erally ribbed or winged on both margins, but sometimes without 
 an apparent rib and sometimes dorsally knobbed or toothed ; style 
 persistent, recurved, J^-i line long. In var. muricata, Morong, 
 which occurs in Texas and California, the fruit has distinct teeth 
 on the back and is bristly-muricate on the sides. All these forms 
 may sometimes be found on a single plant, or, at least, in the same 
 cluster, and can hardly be regarded as varieties. 
 
 Fresh and brackish ponds and pools, sometimes in tidewater. 
 Common throughout Canada and the United States, as well as in 
 all other parts of the world. (Plate LXIV.) 
 
 7. NAIAS. L. Sp. PI. 1015 (1753). 
 
 Slender, branching plants with fibrous roots, wholly submerged. 
 Leaves opposite, alternate or verticillate in 3's or more, sheathing 
 at the base, nerveless. Flowers monoecious or dioecious, axillary, 
 solitary, sessile or pedicellate. Sterile flower with a double peri- 
 anth, the exterior one entire or 4-horned at the apex, the internal 
 hyaline, adhering to the anther; stamen sessile or stipitate, 1-4- 
 celled, apiculate or 2-lobed at the apex, rupturing irregularly. 
 Fertile flower of a single ovary which tapers into a short style
 
 58 
 
 that is split somewhat irregularly into 2-4 subulate stigmas. The 
 mature carpel is solitary, sessile, ellipsoidal, with a crustaceous 
 pericarp; seed conformed to the pericarp, and the embryo to the 
 seed, the plumule and radicle immersed. Generally the raphe is 
 distinctly marked on the seed. 
 
 About 10 species are known, inhabitants of fresh water in 
 tropical and temperate regions. Four species occur in North 
 America, three of them belonging to the section Caulinia, as con- 
 stituted by Willdenow, that is, species with the stems and backs 
 of the leaves unarmed. 
 
 i. NAIAS MARINA, L. Sp. PL 1015 (1753). 
 N. major, All. Fl. Fed. ii. 221 (1785). 
 
 A dioecious plant with rather stout compressed stems com- 
 monly armed with teeth half as long as their breadth. Leaves op- 
 posite or in 3's, 6-18 lines long, about I line broad, with 6-io 
 spine-pointed teeth on each margin, and frequently several along 
 the back. Sheaths with rounded lateral edges, the type form 
 without teeth. The teeth vary much in size and number. Some- 
 times the stem is entirely naked, sometimes with only one or two 
 teeth. The teeth on the leaf margins have a large basal prominence 
 which often imparts a zig-zag appearance to the outline, this 
 prominence being composed of several cells which buttress the 
 yellow, I -celled spine at the tip. Fruit large (2-2^2 lines long), 
 the pericarp, as well as the seed, rugosely reticulate, tipped with 
 a long, persistent style and 3 thread-like stigmas ; seed not shin- 
 ing. A polymorphous species, the extreme forms of which would 
 hardly be recognized as belonging together. A. Braun enum- 
 erates 6 forms, of which his variety Ehrcnbergii, with unarmed stem, 
 the edges of the sheath furnished with 1-2 teeth, occurs in Florida 
 (Dr. E. Palmer); and his variety intermedia, or very nearly that, with 
 long, naked internodes, leaves narrow, linear, each margin with 5 
 or 6 large teeth, which are usually longer than the breadth of the 
 leaf, without dorsal teeth, the sheath on each side with 1-4 teeth, 
 and fruit nearly 3 lines long, occurs in Lake Cayuga, New York 
 (Morong). 
 
 Besides these the two following well-marked forms occur in the 
 United States :
 
 59 
 
 Var. GRACILIS, Morong, Bot. Gaz. 10, 255 (1885). 
 
 Internodes 1-3 inches in length, with a few teeth near the 
 upper part. Leaves scarcely ^ line wide, with 15 to 24 large 
 teeth on the margins and few dorsal teeth ; sheaths with 2-3 teeth 
 on each margin ; seeds hardly 2 lines long and sculptured with 
 about 25 rows of nearly square or irregularly oblong reticulations. 
 The whole plant, at least when dry, purple tinged. 
 
 Florida (A. H. Curtiss, No. 2705). A form very nearly, if not 
 quite this, was collected by Prof. Wm. R. Dudley off Canoga 
 marshes, New York (Cayuga Flora, p. 104). 
 Var. RECURVATA, Dudley, Cay. Fl. 104 (1886). 
 
 Stems dichotomously branched, the branches and leaves re- 
 curved. Leaves 3-6 lines long, narrow, with 2-4 large teeth on 
 each margin longer than their breadth, without dorsal teeth ; inter- 
 nodes short, naked, or with I or 2 teeth; sheaths I -toothed on 
 each side. 
 
 Black Lake, Cayuga Marshes, New York (Dudley). 
 
 The species rare in North America. Canoga Marshes and 
 Cayuga Lake, N. Y. (Morong, Dudley) ; Florida (Chap. Fl.) ; 
 Utah (Parry) ; Lower California (Palmer.) Attributed by Watson 
 in Bot. Cal. to Clear Lake (Bolander) and Huntington Valley, 
 Nevada (Wheeler). Cuba. Occurs in Europe and Asia. (Plate 
 LXV.) 
 
 2. NAIAS FLEXILIS (Willd.) Rostk. and Schmidt. Fl. Sed. 384 
 
 (1824). 
 
 Cauliniaflcxilis, Willd, in Act. Ac. Berol. 89 (1798). 
 Naias Canadensis, MX. Fl. ii. 220 (1803). 
 
 Stems slender, dichotomously much branched. Leaves linear, 
 pellucid, acuminate or abruptly acute, */-! inch long by y^-\ line 
 wide, numerous and crowded on the upper part of the branches, 
 with 25-30 minute I -celled teeth on each edge; sheaths obliquely 
 rounded, with 5-10 teeth on each edge. Dioecious. Fruit ellip- 
 soidal, with very thin pericarp, i-i ^ lines long and ^-/^ of a line 
 in diameter; style long, divided into 3 short stigmas, persistent ; 
 seeds smooth, shining, sculptured, sometimes quite faintly, with 
 30-40 rows of squarish or hexagonal reticulations which are 
 scarcely seen through the pericarp. The seeds are generally
 
 60 
 
 straw colored, but sometimes quite dark; pericarp dull and dark. 
 This species occurs in various forms, some of them very small and 
 bushy, 2 or 3 inches high, others a foot or more high, and nearly 
 capillary, the foliage generally a dusky purple, but sometimes a 
 bright green. 
 Var. ROBUSTA, Morong, Bot. Gaz. x. 255 (1885). 
 
 Stem stout, comparatively few leaved, internodes long, sparsely 
 branched, 3-6 feet high. 
 
 Ponds and rivers in Eastern Massachusetts, New York, Michi- 
 gan and Texas. 
 
 The typical plant is widely diffused in North America, being 
 found in Canada, from the Atlantic to the Pacific, and equally 
 common in the United States and Mexico. It is as widely dis- 
 tributed in the Old World. (Plate LXVI.) 
 
 3. NAIAS GUADALUPENSIS (Spreng.) Morong. 
 
 Caulinia Gnadalupcnsis, Spreng. Syst. i. 20 (1826). 
 
 N. flexilis, var. ( ? ) fusiformis, Chap. Fl. /^/|/| (1860). 
 
 N. flexilis, var. Giiadalupcnsis, A. Br. Seeman's Jour. Bot. ii. 274 
 
 (1864). 
 N. inicrodon, var. Gnadalupensis, A. Br. Rep. Nat. His. Soc. Berl. 
 
 June 1 6, 1868. 
 ,Y. uiicrodon, Morong, 'Bot. Gaz. x. 255 (1885). 
 
 Stems almost capillary, 1-2 feet high, numerously and widely 
 branched from the base. Leaves numerous, /^-^ of an inch long, 
 /^-/^ of a line broad, acute, opposite or 3-5 fascicled, frequently 
 recurved, with sheaths and teeth like those of N. flexilis, but gen- 
 erally with 40-50 teeth on each edge of the leaf. Fruit about I 
 line long; pericarp dark and strongly marked by 16-20 rows of 
 hexagonal or rectangular reticulations which are transversely ob- 
 long; seed straw-colored, not shining. 
 
 This species is easily confounded with N. flexilis, but is clearly 
 distinct in its long narrowly outlined branches, its short leaves, 
 and especially in the markings of the fruit and seed. 
 
 Florida (A. H. Curtiss, Chapman); Louisiana (Langlois); Texas 
 (Lindheimer, Reverchon); Nebraska (T. A. Williams); Oregon 
 (Howell). West India Islands (Duchassaing, Wright). Mexico 
 (Muller)'. (Plate LXVII.)
 
 61 
 
 4- NAIAS GRACILLIMA (A. Br.) Morong. 
 
 A T . Indica, Willd. var. gracillima, A. Br. by Engclmann in A. 
 
 Gray, Man. Ed. 5, 68 1 (1868). 
 
 Stems almost capillary, 6-15 inches high, much branched, the 
 branches alternate ; the whole aspect of the plant very graceful. 
 Leaves numerous, opposite or often fascicled, 3-5 or more in the 
 bundle, setaceous, ]/ 2 -2 inches long, usually with about 20 minute 
 teeth on each margin. The marginal teeth are erect, with i -celled 
 yellowish spiny tips as in the other species, buttressed by 2, some- 
 times 3 cells on the basal protuberance which give them the aspect 
 of being 3 or more celled. Sheaths auricled, with 6 or 7 teeth 
 on each auricle, the teeth standing upon setaceous divisions of the 
 sheath. Dioecious. Styles bifid, the 2 stigmas very short. Fruit 
 oblong cylindrical, about ^ line long by */ line in diameter, 
 slightly curved inwardly, the pericarp straw-colored or often pur- 
 plish, marked by about 25 rows of irregularly oblong reticulations; 
 seed not shining. 
 
 This plant differs very decidedly from N. Indica, of which Braun 
 made it a variety. It has more slender and longer leaves, smaller 
 and fewer teeth, and different fruit from that of N. Indica, which is 
 described as ovate. It has sometimes been called N. minor, a 
 very different species, which is not known to occur in this country. 
 
 In pools and ponds, still water, Ashland, Worcester, Winches- 
 ter and Stoneham, Mass. (Boott, Morong); Albany, New York 
 (Peck) ; Woodstown, New Jersey (Commons). Tidal mud of the 
 Delaware, Camden, New Jersey, and Bristol, Pa. (Porter); Missouri 
 (Engelmann.) (Plate LXVIII.) 
 
 8. ZOSTERA, L. Sp. PI. 968 (1753). 
 
 Marine plants with slender rhizomes which root at the joints. 
 Stems branching, compressed. Leaves distichous, sheathing at the 
 base, the sheaths stipuliform, with inflexed margins. Spadix linear, 
 contained in a spathe which is merely a sheath with overlapping 
 flaps in the lower part of a leaf, or, as some botanists prefer to say, 
 the spathe is on a long peduncle and has a long foliaceous ap- 
 pendage at the top. Upon the spadix the two kinds of flowers 
 are arranged alternately in two rows. Sterile flower merely an 
 anther attached to the spadix near its apex, i-celled, opening
 
 62 
 
 irregularly on the ventral side ; pollen threadlike. Fertile flower 
 fixed on the back near the middle ; ovary attenuate into a style as 
 long as itself; stigmas 2, capillary. Mature carpels flask-shaped, 
 membranaceous, rupturing irregularly, beaked by the persistent 
 style. Seeds ribbed, the ribs showing through the dried pericarp, 
 enclosed in a firm membranaceous test; embryo thick, ellipsoidal, 
 the cotyledonary end contained in a longitudinal furrow. 
 
 Species 5 or 6, natives of temperate seas throughout the world. 
 Of these 3 are found on the North American coast. 
 
 I. ZOSTERA MARINA, L. Sp. PL 968 (l753). 
 
 Leaves ribbon-lrke, obtuse at the apex, 1-5 feet or more long 
 and 1-4 lines wide, having 3-7 principal nerves and many fine 
 ones between them, the nerves often obscure. The sterile plants 
 are generally larger and more vigorous than the fertile. Spadix 
 2^-2 1^ inches long ; flowers about 3 lines in length, crowded, 
 varying greatly in the proportionate number of each kind, and 
 from 10 to 20 of each. Sometimes the anthers are arranged 
 obliquely in 2's and 3's. Ovaries somewhat vermiform. At 
 anthesis the stigmas are thrust through the opening of the spathe 
 and drop off before the anthers on the same spadix open, showing 
 that they are fertilized by pollen from other plants. The anthers 
 at the time of anthesis work themselves out of the spathe and dis- 
 charge the sticky, stringy pollen in the water, thus leaving the 
 ovaries by themselves, which then appear regularly disposed in 
 two rows. Seeds cylindrical, strongly 2O-ribbed, about i l / 2 lines 
 long and y 2 line in diameter, truncate at both ends. The ribs 
 show very clearly on the pericarp. 
 
 The plant described under the name Z. Orcgana, by Dr. S. 
 Watson in Proc. Am. Ac. 26. 131 (1891), was founded upon a 
 single specimen in the Gray Herb., collected by Hall in Oregon in 
 1871. A careful examination of this shows that it is only our 
 common Z. marina. The only substantial points on which Mr. 
 Watson relies to establish the species are the long straight beak of 
 the fruit and the lack of a foliar appendage on the spathe. The 
 beak is characteristic of all Zostera fruit, and the single spathe on 
 Hall's specimen has the appendage broken off, as the jagged edges 
 seen under a lens distinctly show. I have seen scores of them in
 
 tf8 
 
 dried specimens broken off in the same way. In every other re- 
 spect the plant is Z. marina. 
 
 This species is common in sheltered bays and marsh ditches 
 between high and low water mark along the Atlantic coast from 
 Greenland to Florida, and on the Pacific coast from Alaska to 
 California. Europe and Asia. (Plate LXIX.) 
 
 2. ZOSTERA MINOR (Cavol.) Nolte, in Reich. Ic. vii. 2 (1845). 
 Phucagrostis minor, Cavol. Phuc. Th. Anth. xiv. (1792). 
 
 Z. nana, Roth, Enum. PI. Germ. p. 8 (1827). 
 
 A specimen which probably belongs to this species, collected 
 at Key West, Florida, by Blodgett is in the Torrey Herb. Leaves 
 3-6 inches long, scarcely ^ of a line wide, I -nerved. It lacks fruit, 
 however, to make its rank sure. The seeds of this species in 
 English specimens are about ^ of a line long, and smooth or very 
 faintly striate, only 4 or 5 maturing in the spathe. (Plate LXX.) 
 
 3. ZOSTERA LATIFOLIA, Morong. 
 
 Z. marina, L. var. (?) latifolia, Morong, Bull. Torr. Club, xiii, 160 
 
 (1886). 
 Z. Pacifica, S. Watson, Proc. Am. Ac. 26, 131 (1891). 
 
 Rootstocks very thick, sending up a stout stem which is some- 
 times 8 or 10 feet in length. Leaves 2-4 feet long, 3-6 lines 
 wide, the broadest having from 10 to 13 nerves and 7 or 8 striae 
 between each pair of nerves. Spadices 2-3 inches in length. 
 Fruit 1^2-2 lines long by about I line in diameter, cylindrical, 
 with a straight beak as long as itself and attached to the spadix 
 by a short stipe, distinctly 20-25 costate. Pericarp membranaceous, 
 splitting regularly along the face, the ribs of the seed marked upon 
 the pericarp in the dried specimens. 
 
 Puget Sound (Nevins); Santa Barbara, Cal. (Mrs. R. F. Bing- 
 ham); Bolinas Bay (Prof. E. L. Greene). Monterey (Dr. C. L. 
 Anderson). (Plate LXXI.) 
 
 9. PHYLLOSPADIX, Hook. Fl. Bor. Am. ii. 171 (between 1834 
 
 and 1840). 
 
 Submerged marine plants with thickened rootstocks, sending 
 up slender stems which bear the inflorescence at the summit or 
 in clusters along the upper part. Leaves linear, grass-like, sub-
 
 (54 
 
 coriaceous, sheathing. Flowers dioecious, in spathes like those of 
 Zostera. Spathes with membranous edges, the back thickened 
 and terminating in long, leaf-like appendages. Spadix with a 
 series of short, dilated, foliaceous flaps, which close over the 
 flowers, spreading open at maturity. Sterile flowers of numerous 
 sessile stamens, in two rows lying obliquely crowded against each 
 other, i -celled, dehiscing by a ventral slit, dorsally attached near 
 one side about half-way up ; pollen thread-like. Fertile flowers of 
 sessile ovaries, attached above the base, attenuate into a short 
 style; stigmas 2, capillary; ovules pendulous, orthotropous. Fruit 
 coriaceous, indehiscent, beaked by the short persistent style, cor- 
 date-sagittate, projecting at base into 2 recurved wings or lobes, 
 and attached to the spadix between them. Seeds globose, with 
 a thick, membranous test; embryo thick, the radicular end 
 flattened ovoid, the cotyledonary end cylindraceous and curved 
 upon the radicle. 
 
 Two species only are known, occurring upon the Pacific coast ; 
 also on the Asiatic coast. 
 
 i. PHYLLOSPADIX TORREYI, S. Watson, Proc. Am. Ac. xiv. 303 
 
 (1879). 
 
 Rootstock usually covered with the fibrillose remains of old 
 leaves. Stems slender, flat, 20 or more inches in height, bearing 
 the spathes in clusters along the upper part. Leaves 3-6 feet in 
 length, ^-^ line wide, thick, opaque, smooth, obscurely 1-3 
 nerved, blackening in drying ; sheaths very long with narrow, 
 whitish, membranous edges. Spathes 2 or 3 in a cluster, 1-2 
 inches long, slightly curved, with broad, whitish membranous 
 edges, each spathe on a peduncle l / 2 -i inch in length. Append- 
 ages of the fruiting spadix elliptical, those of the sterile oblong- 
 ovate, both obtuse. Stamens cylindraceous, obtuse at both ends. 
 Ovaries flask-shaped, in fruit laterally flattened and carinate on the 
 back, about 3 lines long. Stigmas long, thrust out of the spathe 
 at anthesis. Test reddish, somewhat shining. 
 
 Growing on rocks which are uncovered at low tide. 
 
 Santa Barbara, Cal. (Mrs. R. F. Bingham); Los Angeles (Parish 
 Brothers); Bolinas Bay (Prof. E. L. Greene). July-August. (Plate 
 LXXII and LXXIV.)
 
 65 
 
 2. PHYLLOSPADIX SCOULERI, Hook. Fl. Bor. Am. ii. 171, t. 186 
 
 (before 1840). 
 
 Stems very short, an inch or two in height, bearing solitary 
 spathes. Leaves 3-6 feet long, 1-2 lines wide, 3 nerved, with 
 many fine striae between the nerves. Spadix appendages on both 
 kinds of flowers elliptical, y 2 inch long. Fruit broadly flattened, 
 the lobes half as long as the body. In general appearance and 
 inflorescense this is similar to the preceding species, but may be 
 distinguished by its broader leaves, and especially by its short 
 stems and single spathes. 
 
 Barclay Sound, Vancouver's Island (Macoun); Tilamook Head, 
 Oregon (Henderson); Dundas Island, Columbia River, Oregon 
 (Scouler). Russian River, Siberia (Ruprecht). (Plates LXXIII 
 and LXXIV.) 
 
 Since the sheets of this monograph went to press, I have re- 
 ceived specimens of Potamog e ton folio sus var. Niagarensis, collected 
 by Mr. C. F. Wheeler in Cedar River, on the grounds of the Agri- 
 cultural College in Michigan. 
 
 Also P. nttilus, Wolfg., collected by the same gentleman in the 
 Detroit River, July 19, 1892. 
 
 Of the following plates a part were prepared by the author for 
 another work, and are here used by permission.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XX. 
 
 TRIGLOCHIN PALUSTRIS, L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXI. 
 
 TRIGLOCHIN STRIATA, R. & P.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXII. 
 
 TRIGLOCHIN MARITIMA. L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXIII. 
 
 SCHEUCHZERIA PALUSTRIS, L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXIV. 
 
 LIL^EA SUBULATA, H. & B.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXV. 
 
 POTAMOGETON NATANS. L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXVI. 
 
 POTAMOGETON OAKESIANUS, ROBBINS.
 
 MEMOIRS TORREY BOTANICAL CLUB PLATE XXVII. 
 
 POTAMOGETON AMPLIFOLIUS, TUCKERM.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXVIII. 
 
 POTAMOGETON PULCHER, TUCKERM.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXIX. 
 
 POTAMOGETON NUTTALLII. C. & S.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXX. 
 
 POTAMOGETON ALPINUS, BALBIS.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXXI. 
 
 POTAMOGETON LONCHITES, TUCKERM.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXXII. 
 
 POTAMOGETON FAXONI, MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE xxxnf 
 
 POTAMOGETON MEXICANUS, A. BENNETT.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXXIV. 
 
 POTAMOGETON HETEROPHYLLUS, SCHREB.
 
 MEMOIRS TORREY BOTANICAL CLUB.-PLATE XXXV. 
 
 POTAMOGETON SPATHUL^EFORMIS (ROBBINS) MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXXVI. 
 
 POTAMOGETON ILLINOENSIS, MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXXVII. 
 
 POTAMOGETON ANGUSTIFOLIUS, BERCH. & PRESL.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXXVIII. 
 
 POTAMOGETON LUCENS, L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XXXIX. 
 
 POTAMOGETON PR^ELONGUS, WULF.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XL. 
 
 POTAMOGETON PERFOLIATUS, L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XLI. 
 
 POTAMOGETON MYSTICUS, MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XLII 
 
 POTAMOGETON CONFERVOIDES REICHENB.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XLI1I. 
 
 POTAMOGETON CURTISSII, MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XLIV 
 
 POTAMOGETON CRISPUS, L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XLV. 
 
 POTAMOGETON ZOSTER^FOLIUS, SCHUM.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XLVI. 
 
 POTAMOGETON HILLII, MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XLVI1. 
 
 POTAMOGETON FOLIOSUS, RAF.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XLVIII. 
 
 POTAMOGETON OBTUSIFOL1US, M. AND K.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE XLIX. 
 
 POTAMOGETOX MAJOR (FRIES) MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE L. 
 
 POTAMOGETON RUTILUS, WOLFG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LI. 
 
 TOTAMOGETON VASEYI, ROBBINS.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LII. 
 
 POTAMOGETON LATERALIS, MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LIU. 
 
 POTAMOGETON PUSILLUS, L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LIV. 
 
 POTAMOGETON GEMMIPARUS (ROBBINS) MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LV. 
 
 POTAMOGETON DIVERSIFOLIUS, RAF.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LVI. 
 
 POTAMOGETON SPIRILLUS, TUCKERM.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LVII. 
 
 POTAMOGETON FILIFORMIS, PERS.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LVIII. 
 
 POTAMOGETON PECTINATUS, L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LIX. 
 
 POTAMOGETON LATIFOLIUS (ROBBINS) MORONG
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LX 
 
 POTAMOGETON INTERRUPTUS, KIT.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXI. 
 
 POTAMOGETON ROBBINSII, OAKES.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXII. 
 
 RUPPIA MARITIMA. L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXIII. 
 
 RUPPIA OCCIDENTALS, S. WATSON.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXIV. 
 
 ZANNICHELLIA PALUSTRIS, L.
 
 MEMOIRS TORREY BOTANICAL CLUB PLATE LXV. 
 
 NAIAS MARINA, L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXVI. 
 
 NAIAS FLEXILIS (WILLD.) ROSTK. AND SCHM.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXVII. 
 
 A 
 
 NAIAS GUADALUPENSIS (SPRENG.) MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXVIII. 
 
 NAIAS GRACILLIMA (A. BR.) MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXIX. 
 
 ZOSTERA MARINA, L.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXX. 
 
 NAIAS MINOR (CAVOL) NOLTE.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXXI. 
 
 ZOSTERA LATIFOLIA, MORONG.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXXII. 
 
 PHYLLOSPADIX TORREYI, S. WATSON.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXXIII. 
 
 PHYLLOSPADIX SCOULERI, HOOK.
 
 MEMOIRS TORREY BOTANICAL CLUB. PLATE LXXIV. 
 
 PISTILS, SPADIX AND FRUITS OF PHYLLOSPADIX. 
 i, 2. P. SCOULERI. 3, 4. 5- V. TORREYI.
 
 4694 8
 
 UNIVERSITY OF CALIFORNIA AT LOS ANGELES 
 
 THE UNIVERSITY LIBRARY 
 This book is DUE on the last date stamped below 
 
 Form L-9-20m-8,'37 
 
 LOS A
 
 495 llorong- 
 
 of irrth 
 Jbaorioft. 
 
 QK 
 
 495 
 
 N14148 
 
 000 864 015