374 95. POIAMOGETONACE^. 



12. P. longifdlius (Gay?); Z. pellucid long-lanceolatenaxrovreA 



■below cniiVe cuspidate, stip. winged, £r ,ped. long swelling 



upwards, spikes with few ratlierwhorled distantflowers. — E.B.S. 

 2847. — St. long, slender. L. distant, not denticulate, nearly 

 sessile, with very short stalks. Stip. green, lanceolate, with 2 

 narrow wings on the back. Ped. 6 — 8 in. long, much thicker 

 than the stem. Spike 1 in. long ; fl. rather more whorled than as 

 represented in E. B. S, Fr. unknown. — ^Deep water. Lough 

 Corrib, Galway. P. YIH. I. 



13. P. pralon'gus (Wulf.) ; I. pellucid oblong-lanceolate half- 

 clasping blunt and hooded at the end entire, stip. not winged, fr. 

 keeled on the back when fresh heeled or winged when dry, pe- 

 duncle very long equal, spikes many-flowered. — E. B. S. 2858. 

 P. vii. 33. — St. long, growing in deep water. Peduncles 6 — 12 in. 

 long. Spikes 1 — 2 in. long. — Rivers and ditches, rare. P. V. 

 VL E. S. I. 



14. P. perfolidtus (L.) ; st. round, I. pellucid cordate-ovate 

 clasping not hooded, fr. rounded on the back when fresh keeled 

 when dry, peduncle equal.— ^. B. 168. P. vii. 29. — St. long, 

 slightly branched, rather dichotomous at the top. Peduncles 

 rather thick and short. Spikes short. — Lakes and streams. 

 P. VIL E. S. I. 



15. P. cris'pus (L.) ; st. compressed, I. pellucid linear-oblong 

 blunt sessile serrate wavy, fr. with a long beak keeled on the 

 back when dry, peduncle equal. — E. B. 1012. P. vii. 29 — 30. 

 — St. much branched. Ped. long. Spikes few-flowered. Beak 

 as long as the nut. L. usually crisped at the edges, occasionally 

 flat (P. serratus Huds.). — Ditches and streams. P. VI. E. S. I. 



*** L. all submersed, altei'nate, linear; stipules free. 



16. P. zosterifdlius (Schum.) ; st. flattened, I. linear-acumi- 

 nate with 3 principal and many close parallel intermediate reins 

 occupying the whole surface, spikes cylindrical upon long ped., 

 sep. transversely oval, fr. oljovate keeled, style terminal. — 

 E. B. 8. 2685. P. vii. 27. P. cuspidatus Sm., P. compressm 

 Fries, Hook. — Ped. 2 — 4 in. long. Spikes 10 — 15-flowered. 

 Inner edge of fr. rounded ; faces a little convex. L. suddenly 

 acuminate or apiculate. Rivers and lakes. P. VI. E. S. I. 



17. P. acutifilim (Link) ; st. flattened, I. linear acuminate 

 with 3 principal and many close parallel intermediate veins occu- 

 pying the whole surface, spikes ovate about as long as the short 

 perf., Sep. rhomboidal, fr. broadly J-obovate compressed innei- 

 edge strmght with u, tooth near its base keeled, style facial, — 



