440 95. POTAMOGETONACE^:. 



the base of the uppermost submersed L J". of 1?. xxvii. (1889) p. 33' 

 t. 287. P. spathulceformis (Morong.). St. usually but little branched- 

 Fen ditches. Cambs. P. VIII. E- 



** L. usually all submersed, membranous, lanceolate or broader ; 

 stipules free. 



14. P. Zizii (Roth) ; 1. pellucid narrow-lanceolate-oblong cus- 

 pidate narrowed doivnwards minutely denticulate near the end 

 wavy, stip. long broad broadly and doubly keeled not winged, 

 fr. with 3 keels, ped. swelling upwards, very long. J. of It. 

 xvii. p. 291, t. 204. St. long, much branched, lower 1. usually 

 recurved. Sometimes with aerial 1. short stalked rather cori- 

 aceous oblong acute at both ends. Ped. straight, 4 6 in. long, 

 thicker than the stem exceeding the 1. terminal. Spike about 

 1 in. long. [P. involutus (Fryer) is P. Zizii X perfoliatus.] Lakes, 

 rivers, &c. P. VII. VIII. E.S.I. 



15. P. lucens (L.) ; /. pellucid oval or lanceolate stalked mi- 

 nutely denticulate and cuspidate, stip. winged, fr. rounded on the 

 back and slightly keeled when fresh, peduncle swelling upwards, 

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

 All the stipules have two prominent wings on their back. Spikes 

 long, about equalling the peduncles. A form (?) has been found 

 with ovate-lanceolate subacute subcoriaceous floating leaves 

 ( var. coriaceus Nolte ? R. 39) which looks different. [Var. cori- 

 aceus (Nolte) is thought by Mr. Fryer to be probably P. heterophyllus X 

 Ziz'ti. He writes " upper 1. coriaceous like heterophyllus but petiole shorter 

 than lamina."] Sometimes (P. acuminatus Schum.) the midrib 

 forms a long prominent point. Common in deepish water. 

 P. VI. E. S. I. 



16. ?P. decip'iens (Nolte) ; /. pellucid oblong rounded below not 

 hooded but blunt mucronate and wavy at the end entire sessile 

 or uppermost 1. sometimes subsessile, stip. not winged l , fr. 

 " like that of P. lucens," ped. equal./, of B. v. t, 61. R. vii. 

 35. St. long, much branched. Ped. 1 2 in. long, thicker than 

 the stem. Spikes 1 2 in. long, dense, [p. lucens x perfoliatus 

 Fryer.] Canal near Bath. Forfar. Navan Canal, [&c.J. P. VII. 



E. S. I. 



17. P. longifolius (Bab. not Gay) ; /. pellucid long -lanceolate 



narrowed below entire cuspidate, stip. winged, fr , ped. 



long swelling upwards, spikes with few rather whorled distant 

 flowers. E. B. S. 2847. St. long, slender. L. distant, not 



1 I cannot find the wings described by Symej nor did Mr. Baker. 

 J. ofB. v. 71. 



