POTAMOGETON. NAJADACE^. 255 



3. PoTAMOGETON HYBRiDus, Mlchx. Small Floating Pondweed. 



Stem sparingly branched, filiform ; floating leaves (small) oval, coriaceous, petiolata, 5-7- 

 nerved ; submerged leaves setaceously linear ; spikes short, dense ; the peduncle thick and 

 somewhat clavate ; fruit crested, very obtuse, flat on the sides. — Michx. fl. 2. p. 101 ; 

 Cham. Sf Schle.cht. I. c. ^.208. t. 5. /. 17; Kunth, enum. 3. p. 132. P. diversifolium, 

 Bart, compend fl. Phil. \.p. 96. and^. Amer. Sept. 3. t. 84 ; Torr. fl. \.p. 197 ; Hook.fl. 

 Bor.-Am. 2. p. 172. P. porcatum, Muhl. cat. p. Ill P. helerophyllum, Pursh, I. p. 120 ; 

 Ell. sk. 1. p. 2221; Beck, hot. p. 385, not of Willd. ' 



A slender neat species. Floating leaves from three-fourths to an inch in length, distinctly 

 7-nerved, rather obtuse ; the petiole shorter than the lamina : submerged leaves scarcely a 

 line wide, 1 —2 inches long, 1-nerved, veinless, without linear reticulations. Stipule lanceolate. 

 Spikes about one-third of an inch long, on short thick peduncles. Fruit minute, roundish? 

 truncate, keeled and somewhat winged on the back. Seed cochleate, forming nearly two 

 complete turn§. 



Shallow slow streams : frequent. Fl. July. Fr. August. This species resembles P. 

 natans in miniature. The fruit difiers from that of most other species : a cross section of it 

 exhibits three portions of the seed. 



** Ijcaves aU submerged and similar [the upper ones sometimes petiolate), memhranaceous and peUucid, reiiculately nerved. 



4. Potamogeton lucens, Linn. Shining Pondweed. 



Leaves elliptical and elliptical-lanceolate ; the upper ones sometimes petiolate, mucronate, 

 coarsely reticulated, the nerves arising from the midrib ; spikes cylindrical, dense, supported 

 on thick peduncles ; fruit compressed, slightly carinate. — Linn. sp. 1. p. 126 ; Michx. fl. 2. 

 p. 101 ; Pursh, fl. 1. p. 120; Torr. fl. 1. p. 197 ; Bigel. fl. Bost. p. 6S ; Beck, hot. 

 p. 386 ; Darlingt. fl. Cest. p. 116 ; Kunth, enum. 3. p. 132. P. Proteus, Cham. <^ Schlecht. 

 I. c. p. 196. t. 5. f. 16. 



A polymorphous species. Stem a little branching, rather slender. Leaves usually all 

 submersed, thin and shining, 2-4 inches long ; the upper often abruptly narrowed at the base 

 into a petiole, from three-quarters of an inch to more than an inch wide, mucronate and often 

 acuminate, marked with 12-17 nerves which are connected by strong transverse veins : 

 petiole half an inch to an inch long : submersed leaves lanceolate, sessile but attenuate at the 

 base. Stipules elongated and narrow. Peduncles shorter, or sometimes much longer than 

 the leaves, usually much stouter than the stem. Spikes about an inch long. 



Small streams and outlets of lakes. Fl. August. Fr. September. The lower leaves are 

 usually sessile and lanceolate or oblong-lanceolate, but often (in shallow water) they are 

 petiolate ; sometimes very large (5-6 inches long), at other times quite small. They are 

 spreading or recurved. The margin is slightly rough. 



