POTAMOQETOir. 381 



iDranched. Floating 1. not always present witli the flowers. No 

 fruit even on Sept. 28. — By tlie bridge at Penrhos Lligwy, 

 Anglesea. Burwell Fen, Cambr. P. VII.— IX. E. 



6. P. sparganiifdlius (Laest. !) ; sribmersed I. linear narrowed 

 at both ends very long sessile entire not apiculate mith many 

 parallel veins next the midrib, floating 1. subooriaceous lanceolate 

 loDO'-stalked, stip. very long blunt not winged, fr. "acutely 

 keeled " (Fr.), ped. rather slender not clavate. — Sy. E. B. 1403. 

 — St. very slender, slightly branched. Floating 1. often wanting. 

 Submersed 1. sometimes 2 ft. long, very narrow, few-veined 

 with additional parallel veins closely placed next the midrib. 

 L. very much longer than those of P. lanceolat-us and without 

 the chainlike network, beautifully green when well dried. 

 Exactly the plant of Fries, H. N. xii. 75. — In the river at 

 Ma'am, Co. Galway. I. 



7. P. salicifdlius (Wolfg.) ; submersed I. narroivly strapshaped 

 sessile narrowed at both ends entire not apiculate, floating 1. 

 subooriaceous elliptic long-stalked, stip. long bluntish not 

 winged, f r. obliquely obovate 3-keeled. — P. lonchites Tuck. Sy. 

 JB. B. 1404. — St. slightly branched. Svibmersed 1. with a few 

 additional parallel veins next midvein, subsessile. Floating 1. 

 often wanting. Ped. long, slightly thickened upwards. — In 

 river Boyne near Navan. P. I. 



8. P. heteropliyllus (Schreb.) ; submersed I. lanceolate narrowed 

 at both ends sessile minutely denticulate and apicuiate, floating 1. 

 subooriaceous elliptic stalked, stip. broadly lanceolate blunt tpith 

 2 stout prominent ribs, lower ones linear-lanceolate, /)•. blurd on 

 the bach, peduncle thicker than the stem swelling upwards. — E. B. 

 1285. P. vii. 41 — 43. P.gramineus Fries, not Linn. — St. much 

 branched below. Submersed 1. wavy. Lower stip. without the 

 two strong ribs and equally veined, upper ones widely spreading. 

 Dry fr. slightly marked with 3 ridges on the back.- Ponds and 

 ditches. P. VI. VII. E.S.I. 



9. P. nitens (Web.) ; submersed I. lanceolate rounded below and 

 half clasping wavy at the edge, floating 1. " coriaceous elliptic 

 stalked," stipules equally veined, (dry) fr. keeled, ped. swelling 

 upwards.— P. vii. 34. Sy.E.B.liQT. /. of P. ii. t. 23.— St. 

 rather wavy, branched below. Subm. 1. pellucid, often re- 

 curved ; upper 1. often not coriaceous. Upper stip. large, per- 

 sistent, nearly | as long as the peduncle. Dry fr. with 3 ridges 

 on the back. — Lakes near Brandon Mountain, Kerry (P. curvi- 

 folius Hartm.) Loch Asoog, Bute. Eiver Tay, Perth. Colt- 

 field, Elgin. P. VILVIIL S.L 



