POTAMOGETOX. 437 



L. subcorclate below, when pressed flat a ridge is formed on 

 each side of the base, jointed to their stalks a little beloiv the 

 limb. Sep. stalked, roundly rhomboidal. Anth.-cells not 

 parallel. Fr. greenish, slightly compressed, \\ 2 lin. long. 

 [Var. prolixus (Koch) is an early state having longer and narrower 

 thin and semi-pellucid LP.fluitans (Roth), J. of B. xxvi. (1888) p. 273, 

 is probably P. natansXlucens, and P. crassifolius (Fryer), J. ofB. xxviii. 

 (1890) p. 321, t. 299, is P. natans X Zizii.'] Ponds, ditches, and slow 

 streams. P. VI. VII. E. S. I. 



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

 aceous floating oblong-elliptic or lanceolate subcuspidate, no 

 leafless petioles, lower 1. linear-lanceolate, fr. minute blunt and 

 rounded on the back, peduncle equal. P. oblongus Viv., E. B. S. 

 2849. St. creeping below. Petioles longer than leaves, 

 convex on both sides, not jointed below the limb. Lower 1. often 

 very narrow. Spikes rather short and irregular. Sep. trans- 

 versely elliptic, stalked. Fr. reddish, scarcely compressed, 1 lin. 

 long ; a faint keel and lateral ridges when dry. /3. pseudo- 



Jiuitans (Syme) ; submerged 1. membranous linear-lanceolate 

 narrowed at both ends. [y. cancellata (Fryer); floating 1. few 

 thinner, submersed 1. strongly net-veined.] Ditches^ small streams, 

 and ponds. /3. Buttermere. Gap ot Dunloe, Kerrv. P. VII. 



E. S. I. 



3. P. Griffith' 'ii (Ar. Benn.) ; submersed 1. strap-shaped usually sessile 

 or half-clasping wavy somewhat hooded pellucid 9 16-veined, floating 1. 

 obovate-lanceolate blunt long-stalked more opaque, stip. long usually 

 exceeding the internodes, ped. slender nearly equal. J. of B. xxi. (1883) 

 t. 235. St. branched. Floating 1. green, submersed 1. slightly brownish. 

 Sep. " roundish-oval broader than long." Spikes short. Mr. Fryer con- 

 siders this a hybrid, P. polygonifolius X ? Llyn-an-afon, Carn. 



Mr. J. E. Griffith. P. VI VIII. E. 



4. P. Drucei (Fryer) ; submersed 1. elliptic-lanceolate pellucid strongly 

 reticulate-veined throughout very long stalked, floating 1. obovate elliptic 

 or oval narrowed at both ends, stip. very long, fr. broadly obovoid acutely 

 keeled, keel tubercled with conspicuous angles at the base, ped. thicker 

 than the st. narrowed at both ends. A very distinct plant, producing but 

 little fruit and possibly a hybrid. R. Loddon, Berks. Mr. Gr. C. Druce. 

 P. VII. VIII. E. 



5. P. color dtus (Hornem.) ; /. 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, peduncle equal. E. B. 8. 2848. R. vii. 45. P. planta- 

 gineus (Ducr.) ed. viii. St. creeping below, branched, some- 

 times throwing out long runners from its upper axils. L. all 

 beautifully transparent and netted with veins, the upper often 



