196 TETRANDRTA. TETRAGYNIA. potamookton'. 



ed, sessile. Geji, pi. 254. Hook. Fl. Scot. p. 48. 

 Nuft. Gen.l.p. 111. Juss. p. 19. Lam. III. U 

 LXXXIX. f. 3. Roe m, ^ Sc h ult. Gen. p. 609. 

 Nat. Ord. Naiades Jiiss. Aquatic plants. Leaves 

 sheathing; flowers on axillary and terminal spikes. 



Pond-weedr 



* Upfier leaves Jlaating. 



1, V , natans L, : upper leaves floating, coriaceous, ob- 

 long-ovate, on long peduncles, (subcordate;) lower ones 

 membranaceous, lanceolate, tapering to a footstalk. W ill d. 

 Spec. I. p. 712. Smith Fl. Brit, I. p. 193. Eng. Bot, 

 1822. Pursh Fl.l.p.UO. B i g. Bost. i^. 4U Muhl. 

 Cat. p. 1 7. Roem.^ Schult. III. p. 503. P. natans ^. 

 Mich, FL I. p. 101. 



Root perennial. Stem varying in length, according to the deptb 

 of the water in which it grows. Upper leaves 2 — 3 inches 

 long, an inch and a half, or 2 inches, broad, nerved, often cor- 

 date at the base ; lower leaves very narrow. S/iike (sfiadix^ 

 Hooker,) emerged, an inch or more in length, on a long 

 ■ axillary peduncle, proceeding from a sheathing stipule. Leaves 

 of the calyx roundish. Filaments ; anthers 2-celled, ob- 

 long. J^uts ovate, acute, compressed. 



Hab. In lakes and slow-flowing waters. July — August. 



2. P. jiuitans L. ; upper loaves floating, coriaceous, ob- 

 long-lanceolate, petiolate, tapering at the base ; lower ones 

 linear, sessile. fVilld. Spec. I. p. 713. Smith Fl. Brit. 

 1. p. 194. Eng. Bot. t. 1^6 . P ur s h Fl. I. ^. }'20. El- 

 liott Sk. I. p. 221. Muhl. Cat. p. 17. Roem. ^ 

 Schult. 111. p. 504. P. foliis lanceolato-oblongis, &;c. 

 Gron. Virg. 1 39. 



Stem as in the preceding species. Upper leaves about 3 inches 

 long, nearly an inch broad, tapering at tlie base into a long pe- 

 tiole, of an olive-green colour; lower ones very long and nar- 

 row. Peduncles axiUaiy, abcut as long as the leaves, thick. 



Hab. In ponds and gentle streams. July — August. Perhaps 

 only a variety of P. natans. 



3. P. htle.rophyllum S c hr e h. : upper leaves floatinci, 

 petiolate. elliptical ; lower ones crowded, se^sile, linear. 

 fVilld. Spec. I. p. 713. Smith Fl. Brit. I. p. 19i. Eng. 

 Bo<. t. 1285. Pursh FL I. li. \20. E 1 1 i o 1 1 Sk. i. p. 

 2221* Ro6m.k Schult. III. p. 506. V.hubridum M i ch. 

 FLl.p. 101. 



Resembles P. Jiuitans, but is not half the size. Submerged 



