350 On American Species of the Genus Potamogcton. 



2, p. 210. Fries, Novit., p. 30. Koch. Syn., p. 674 Kth. 

 Enum ., 3, 129. A. Gr. Man. Bot., p. 455. P. oppositifolius^ 

 DC. e Cham. NolL! Nov. HolsaL, p. 17. 



Hab. Stagnant and flowing waters. In the two streams at 

 the foot of Lake George, New York. Also in the rapids of the 

 Niagara near Bath Island, and according to Chamisso in the 

 river Mistassin. Stem terete, (often, as well as the peduncles 

 and petioles somewhat muricate with regular, prickle-like excres- 

 cences,) mostly simple, but in luxuriant states often branching 

 above, the whole plant and especially the upper portion becom- 

 ing more or less purplish-rufescent when dry, 1 J to 3 feet long. 

 Submersed leaves membranaceous, slightly rigid, rather narrowly 

 lanceolate, tapering to the base, and more or less so above to 

 the acutish tip; the upper ones often petiolate, the rest sessile; 

 many-nerved, from 3 to 5 of the nerves more conspicuous ; rather 

 closely netted-veined ; 2-4 inches long by 3-7 lines wide. Float- 

 ing leaves (often wanting) subcoriaceotis, flat, oblong- or obovate- 

 lanceolate, acute above, with about 7 prominent nerves on the 

 under side, 2-4 inches long by 3-9 lines wide, tapering at the 

 base to the compressed, concave-convex petioles, which are 

 shorter than the blade. Stipules rather long, delicate, acute 

 (finely ribbed when dry.) Peduncles scarcely thickened in the 

 smaller plants from Lake George, but evidently so in those from 

 the Niagara, elongated, plano-convex, 2-5 inches long. Spikes 

 cylindrical, many- but not continuously nor densely-flowered, 

 1-2 inches long. Nutlets lenticular-compressed, mucronate with 

 the short style, the sides convex at the middle and sloping each 

 way, the back rather obtusely subalate-carinate, (acute when dry, 

 and the lateial keels often evident.) the face commonly also cari- 

 nate, and acutish. Exocarp thick, produced at the back, and 

 forming the wing. Putamen rather thick and hard. Seed con- 

 volute-uncinate. The exocarp being removed, the back appears 

 acutish, with a sunken line on each side. The American plants 

 above cited agree with the European in every important charac- 

 ter. The Niagara specimens are often branched above, but this 

 is doubtless owing to their luxuriant growth, to which I also at- 

 tribute the thickening of their peduncles. The peculiar murica- 

 tion of the stem, &c, also occurring in the Niagara specimens, I 

 have observed in another species not yet described in this place. 



Potamogeton lonchites, Tuckerm. in Sill. Journ., 1. c. The 

 homophylline or wholly submersed form is common in company 

 with the heterophylline, and with that, is abundant in the Connec- 

 ticut, in Massachusetts, where I have gathered specimens with 

 leaves a foot long. These forms, always characterized by their slen- 

 der habit, long and narrow, very loosely veined, membranaceous 

 submersed leaves, rather rounded petioles, and smallish fruit, ap- 

 pear to extend westward to the Kentucky river, (Dr. Short. Herb. 



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