POTAMOGEIOIT. 373 



often wanting. Ped. Ions', slightly thickened upwards. Very 

 near P. sparganiifoUus. — In river Boyne near Navan. P. I. 



8. P. heterophyl'lus (Schreb.) ; submersed I. lanceolate narrowed 

 at both ends sessile mirmtely denticulate and apiculate, floating 1. 

 Bubcoriaeeous elliptic stalked, stip. broadly lanceolate blunt with 

 2 stout prominent ribs, lower ones linear-lanceolate, fr. blunt on 

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

 1285. R. vii. 41—43. P. gramineus Fries, not Idnn. — 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.— i2. vii. 34. Sy. E. B. 1407. J. of B. li. t. 23.— St. 

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

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

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

 on the back. — Lakes near Brandon Mountain, Kerry. Loch 

 Ascog, Bute. River Tay, Perth. Coltfield, Elgin. P. VII. 



vin. s. I. 



** L. all submei'sed, membranous, lanceolate or broader ; stipules 

 free. 



10. P. lucens (L.) ; I. pellucid oval or lanceolate stalked mi- 

 nutely denticulate and cusmdate, stip. winged, fr. blunt on the 

 back and slightly keeled when fresh, peduncle swelling upwards, 

 spikes cylindrical densely flowered. — E. B. 376. -R. vii. 36. — 

 AU the stipules have two prominent vrings on their back. Spikes 

 long, about equalling the peduncles. Mr. W. Wilson found 

 " ovate-lanceolate moderately acute coriaceous 1." When the 

 limb of the 1. is much reduced in size and the midrib prominent 

 and resembling a long spine, it is the P. ocMmiraafea Schum. — 

 Common in deepish water. P. VI. E. S. I. 



11. ? P. dedp 'iens (Nolte) ; I. pellucid oblong rounded below not 

 hooded but blunt mucronate and wavy at the end entire sessile 

 or uppermost 1. sometimes aubsessUe, stip. not winged', fr. 

 "like that of P. lucens," ped. equal. — J. of B. v. t. 61. 

 JR. vii. 35. — St. long, much branched. Ped. 1 — 2 in. long, 

 thicker than the stem. Spikes 1 — 2 in. long, dense. — Canal 

 near Bath, Cauldsheils Loch, Melrose. Navan Canal. P. VIL 



B. S. I. 



' I cannot find the wings described by Syme ; nor did Mr. Baker. 

 J.ofB.Y.n. 



