tic 



TETRANDRIA. TETRAGYNIA. Potamogeton. 



Leaves heart egg-shaped, verr pellucid, like green oiled silk ; 

 brittle when dry. BIoss. yellowish* 



Perfoliate Pondnveed. Slow rivers and ponds, very common, 



but the fruit-stalk the only part which rises above the surface of 



P. June — Aug. 



the water. 



lu'cens. P. Leaves very long and spear-shaped^ sitting: upper ones 



opposite. 



E. hot. %1^-Kmpl. 5-Ft. dan. 196-Pet. 5. 5-J. B. iii. 777» 

 l~Dod. 582. 2-Ger. 822. 4-i/. ox. v. 29. 4. at p. 596. 



Leaves beautifully green and pellucid, like those of the pre- 

 ceding species ; sometimes 8 inches long, and If broad. Bloss* 

 reddish. 



Long-leaved Pondvoeed. Rivers and ponds, [River Skern, 



near Darlington. Mr. Robson.] 



P. June, July 



den'sum. P. Leaves egg-shaped, tapering to a point: opposite 



crowded: stem forked: spike 4 -flowered. 





E. hot. 397-7- B. iii. 777. 2. 



I 



cris'pum 



o_ 



Fruit-stalk very short, in the fork of the stem. Linn. Bent 

 back. Leaves waved at the edge, crowded towards the end of the 

 stem. Woodward. Leaves strap-spear-shaped, 3-ribbed ; edges 

 very finely serrulated. 



Lesser Water Caltrops. Frogs Lettuce. Close-leaved Pond- 



weed. Ditches and slow streams. P. May, June- 



P. Leaves spear-shaped, alternate or opposite, waved and 



serrated. 



Curt. 5-Fl. dan. 92J-Ger. em. 824. 2-Park. 1248. S-M 

 5. 9-J.B. iii. 778. 1-C/us. ii. 252. 2-Ger. em. 824.2 

 Pari. 1248. 3-Pet. 5. 8. 



Stems branched, flatted. Leaves alternate, at the forks of the 

 stem opposite, sitting, nearly strap-shaped, semi-transparent, 

 very crisp. Spikes as long as the fniit-stalks. Bloss. white or 

 reddish. 



Greater Water Caltrops. Curled Pond<weed* Ponds and slo* 



streams, very common. P. May, J^ nf# 



compres'- P. Leaves strap-shaped, blunt: stem flatted. 



E. hot. 4 18-J7. dan. 206-Pet. 5. 10. 



' Leaves narrower than in the preceding, not waved. $/'*'* 

 shorter than the fruit-stalks. Bloss. greenish. 



Flat-stalked Pondweed. Slow streams and ditches. [R^ tf 



Skern, near Darlington. Mr. Robson.] P. June, July* 



sum. 



