360 On American Species of the Germs Potamogeton. 



Hab. In still and flowing water. In the Connecticut in Mas- 

 sachusetts ; and thence to the Lakes of Western New York, 

 (Prof. Gray!) and Niagara Falls. In the St. Lawrence, {Mi- 

 chaux.) In Lake Ontario, (Pursh !) In Lake Superior, [Prof 

 Agassizf) Southward, New Jersey, (Prof Torrey !) to Louis- 

 iana, (Dr. Ingalls, Hb. Torr. !) Stem a little compressed, 

 plano-convex, much branched at the base, and also above, 1-2 

 feet long. Leaves commonly thickish, but also occurring more 

 delicate, somewhat channelled above and convex below, more 

 or less setaceous-linear, sensibly attenuate above and very acute, 

 below connate with the stipules and clasping; one-nerved; 

 with frequent, thickish veins disposed at right angles to the 



margiu ; 2-4 inches long, by J to % of a line wide. Ligules 



elongated lanceolate, whitish, at length lacerate-setose. Pedun- 

 cles commonly much elongated, filiform, not thickened. Spikes 

 rather long, interruptedly whorled, not many-flowered. Nutlets 

 large, obliquely lunate-obovate, compressed, the broad back ob- 

 tusely carinate, (rather acute when dry,) the lateral keels obso- 

 lete, but indicated by a slightly sunken line, the sides flattish, 

 sloping to the somewhat acute face. Exocarp thick, wrinkled 

 when dry. Putamen very thick, softish. Seed uncinate-eurved. 

 The exocarp being removed, the back appears rounded-carinate, 

 (or in other fruits from the same station, acutely so, as in my 

 French specimens,) the sunken lines on each side, which define 

 the obsolete lateral keels, connivent below the apex of the nutlets, 

 the sides a little convex, and very slightly, or not at all impressed 

 at the middle, the style disappearing, and the whole outline be- 

 coming more elliptical. This description differs in some few 

 particulars from Chamisso's, but our plants are probably insepa- 

 rable, specifically, from the European. P. marinvs, L., e Fr. 

 and Koch, (P. filiformis, Nolte ! and Chamiss.) a species nearly 

 akin to this, but with rather shorter, longer-leaved stems, and 

 small, ecarinate nuts, and peculiar to salt water, is perhaps to be 

 detected here. I have seen a New Jersey specimen that appeared 

 to resemble it, but it was without fruit. 



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