352 On American Species of the Genus Potamogeton. 



species of the Canary Islands. What relation to this the ' P. occi- 

 dentalism Sieber, 7 of the West Indies, (P. fluitans, d. occidental 

 Antillanus, Chamiss. 1. c, p. 224,) may have, must be left to fu- 

 ture investigation. 



Potamogeton gramineus, (L.): caule gracili tereti ramosis- 

 simo, ramis ramosis dense foliosis; foliis submersis membrana- 

 ceis lineari-lanceolatis breviuscule acuminatis basi attenuatisnervis 

 3-6 obscuris, caulinis latioribus, superioribns petiolatis, rameis mi- 

 noribus reliquisque sessilibus, petiolis supra plan is ; natantibus mi- 

 nusculis chartaceo-coriaceis submembranaceisve lanceolatis ellip- 

 ticis ovato-eltipticis ovalisve, petiolis longiusculis compressiusculis 



plano-convexis; stipulis gracilibus lineari-linguiformibus margine 



scariosis acutiusculis ; pedunculis lev-iter incrassatis spicis cylindra- 

 ceis longioribus ; fructibus recentibns minusculis oblique snbro- 

 tundo-obovatis lunatis compressiusculis, stylo brevi subapicali api- 

 culatis, tricarinatis, carinis superne product is acutiusculis, lateribus 

 convexis, facie superne producta obtusa. P. graminevs, L. Suec. 

 2. w. 151, e Fr. Novit , p. 35. Wahl Lapp., p. 52. Koch. 





Syn., p. 674 Kth. Enum. 3, p. 130. P. heterophylhts, Schreb. 

 Spirit. PL Lips., p. 21, e Chamis. Nolt. ! Novit. PL Holsat, 

 p. 18. A. Gr. Man. Bot., p. 455, (excl. P. Claytonii.) P- 

 Proteus y. heterophyllus, Chamiss. in Linncea, 2, p. 202, t v,f. 

 16. c. f g. h. 



Hab. Still and flowing waters; very common in the ponds 

 and streams of New England ; and the lakes of Western New 

 York ; and extending westward to Lake Superior, (Prof. Agas- 

 siz!) Stem slender, terete, in the forms of shallower water 

 much branched, the branches in these forms being also approxi- 

 mated, and all as well as the stem, often terminated by floating 

 leaves ; in those of deep water (as of Lake George, and Seneca 

 Lake, N. Y.) less branched and not at all at the upper extremity, 

 the internodes also much elongated. Submersed branches always 

 ramulose and thickly clothed with leaves, smaller and narrower 

 than those of the stem. Submersed leaves membranaceous, pellu- 

 cid, linear-lanceolate, a little acuminate above, tapering at the 

 base, obscurely 3-6 nerved, obsoletely netted-veined, those of 

 the stem larger and the upper ones more or less petiolate, 2-3 

 inches long, 3 by 5 lines wide, the petioles flat above; those of 

 the branches smaller, more linear, | in. to 1£ inches long by 1-3 

 lines wide. Floating leaves chartaceous, or often submembrana- 

 ceous (or wanting), always rather delicate, from lanceolate vary- 

 ing to ovate and obovate, but very commonly elliptical or ovate- 

 elliptical, with a more or less obtuse base; those of the deep 

 water forms smaller, and commonly subinembranaceous; with 

 about 6-8 inconspicuous, impressed nerves on the under side, 

 on compressed, plano-convex, scarcely elongated petioles Sti- 

 pules of the branches very small, but those of the stem larger, 



