362 94. POTAMOOETONACBiE. 



when diy, peduncle equal. , E. B. 1822t iJ. vii. 50. — St. creep- 

 ing below, simple. Peiiofes plane-concave. L. subcordate below, 

 when pressed flat a ridge is formed on eacb side of the' base, 

 jointed to their stalks, a little below the limb. Sep. stalked, roundly 

 rhomboidal. Anth. -cells not parallel. Fr. greenish, slightly 

 compressed, IJ — 2 liri. long- — Pondsj ditches, and slow streams. 

 P. VI. VII. E.g. I. 



2. P. polyffonifdlitis (Pourr.) ; 1. all stalked, upper subcori- 

 aceous floating oblong-elliptic subcuspidate, no lea/less petioles, 

 lower 1. linear-lanceolate, _/r. minute blunt and rounded on the 

 JacA', pedunoleT equal.^ — P. oblonyus Viv., .B, B. S. 2849. — St. 

 creeping below. Petioles longer than leaves, convex on both 

 sidea,hotjointedbelowtheli>7ib. Lower 1. often very naiTOw. Spikes 

 rather short and irregular. Sep. transversely elliptic^ stalked. 

 Fr. reddishj scarcely compressed, 1 lin. : long ; a faint keel and 

 lateral ridges when dry.^Ditches, ■ small streams, and' ponds. 



P. VII. ' '.. ils.I. 



8. P. plantagir^ eus (Ducr.) ; I. all shortly stalked membranous 

 and pellucid blunt not cuspidate nor plicate, upper elliptic, lower 

 1. oblong, /r. minute rounded on the back when fresh keeled when 

 dry, peduiicle equal. — E. B. 8. 2^48. B. vii: 45. — St. creeping 

 below, branched, sbnietiines throwing oiit long ruaners from its 

 upper* axila. L. all beautifully transparent and netted with 

 vems, the upper often almost sessile and nearly orbicular, some- 

 times slightly cuspidate. Petioles plane-eoncftve above. Spikes 

 long, cylindrical. Anth.-cells nearly parallel. Sep. ovate. Ft. 

 greenish, i.lin. long.^Stagn^nt peaty water. P. VI. VII. 



..'.' ' ,.' ■ I,- ;"' ,. 1 ' . : E.S.I. 



{P.fiuitans (Roth)., A nlant which may be this is in Lamb. 

 Hei-b. s^Kew. It was gathered at Hounslow.] 



4; P. rufe^cens (Schrad.) ;. sMJjnerserf Z. lanceolate , narrowed 

 at both ends subsesaile membranous pellucid entire, not apiculate 

 -with chainlike network near the midrib, floating 1. subcoriaceous 

 obovate blunt narrowed into a short petiole, sim. without wings, 

 fr. acutely keeled, peduncle equal.— ^. B. 1286. B. vii. 32. P. 

 fluitans Sm. — St. simple. Upper 1. alone slightly coriaceous, 

 often tinged with purple, longer than their stalks ; submerged 1. 

 all nearly, if not quite, sessik. Sep. " transversely oval." — 

 Ditches and slow streams. P. VII. E. S. I. 



0. P. lanceot&tus (Sm.) ; submersed I. linear-lanceolate sessile 

 entire not apicidate with chaiidike network near the midrib, float- 

 ing 1. subeoriaceovis elliptic-lanceolate shortly stalked, stip. 

 linear-lanceolate acute uppermost broader^ fr. keeled with faint 

 lateral ridges (stronger when di'v), peduncles equal. — JS. B. 



