POTAMOGETON. 



NAJADACE^E. 



257 



Crooked lake (Dr. Sartivell). Fl. August. I have not seen the ripe fruit of this plant, but 

 there can be little doubt of its being the P. pusillus of Chamisso and Schlechtendal, the var. 

 A. (I. c.) agreeing very minutely with our specimens. 



8. Potamogeton pauciflorus, Pursh. Few-jlowered Pondweed. 



Stem slender, much branched, compressed ; leaves very narrow and linear, acute, membra- 

 naceous, 3-nerved without connecting veins ; spikes capitate, few- (4 - 6-) flowered ; fruit 

 obovoid, convex on the side, apiculate at the summit, cristate on the back. — Pursh, fl. 1. 

 p. 121 ; Torr.fl. I. p. 98 ; Bigel. fl. Bost. p. 64 ; Cham. $ Schlecht. I. c. p. 176. t. 4./. 7; 

 Beck, hot. p. 386; Darlingt. fl. Cest. p. 116; Kunth, enum. 3. p. 136. P. gramineum, 

 Michx. fl. I. p. 102. 



A very slender species, wholly submersed ; the stem almost filiform. Leaves 1-2 inches 

 long, and rarely more than a line wide ; the lateral nerves indistinct. Stipules membranaceous, 

 obtuse or mucronulate, linear-oblong, furnished with a very minute gland on each side at the 

 base. Spikes very short, seldom more than 6-fiowered, on a clavate peduncle about half an 

 inch long. Fruit rather large for the size of the plant, somewhat acuminate, distinctly crested 

 on the back ; the shell thick and hard. 



Ponds, lakes and slow streams. August. Distinguished from the preceding by its smaller 

 stems, narrower leaves, short capitate few-flowered spikes, and crested fruit. 



§ 2. Stipules adnate to the base of the leaves, which are all submerged and si7tiilar inform. 



9. Potamogeton pectinatus, Linn. Fennel-leaved Pondiveed. 



Leaves setaceous-filiform, channelled, with a longitudinal cavity each side of the midrib ; 

 spikes on long peduncles, interrupted. — Linn. sp. 1. p. 127; Pursh fl. 1. p. 121 ; Torr. 

 fl. 1. p. 198; Cham. <§• Schlecht. I. c. p. 164. t. 4. f. 2; Beck, hot. p. 386 ; Kunth, enum. 

 3. p. 137. P. marinum, Linn. I. c. ; Michx. fl. 1. p. 102. P. exstipulatum, Muhl. cat. p. 17. 



Stem filiform, much branched, dichotomous. Leaves distichous, very numerous, very 

 slender, with a tube-like cavity running the whole length on each side of the midrib, attenuated 

 to a fine point. Stipules membranaceous, adnate to the base of the leaf, and forming a 

 sheath. Peduncles mostly elongated. Spike three-fourths of an inch to an inch long, with 

 distinct intervals (which are sometimes considerable) between the clusters of flowers. 



Saltwater ditches and shallow bays, near New- York, and on Long Island. Also in fresh 

 water, near Watertown (Dr. Gray). Fl. August. Fr. October. 

 [Flora — Vol 2.] 33 



