440 
95. POTAMOGETONACEJ;. 
vppermost submersed I. — J. of b. xxvii. (1S89) p. 33, t. 287. P. spaihulcpformis 
(Morong.). — St. usually but little branched. Fen ditches. Cambs. P. VIII. E. 
** L . xistujdly all submersed, membranous, la nceola te or broader ; 
stipidesfi-ee. 
14. P. angustifolius (Berch. k Presl em. Bennett) ; '1. pellucid 
narrov - lanceolate - oblowj cuspidate narrowed doivnivards 
minutely denticulate near the end ivdvy, slip, long broad. 
broadly and doubly keeled not winged, fr. with 3 keels, ped. 
swelling upwards, veiy long.— P. Zizii (Both). — ./. of B. 
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. involutux {VryeT) \s p. angvstiJolius-KpeTtolUitusl\ — LakcS, 
rivers, etc. P. VII. VIII. E. S. 1. 
15. lucens (L.) ; /. pellucid oval or lanceolate stalked mi- 
mitehj denticidate and cuspidate, stip. vinged, fr. rounded on the 
back and slightly keeled when fresh, peduncle swelling upwards, 
spikes cylindrical densely flowered.—^. B. 376. li. 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 Xolte? i?. 39) which looks different, [var. co>-- 
anius (Xolte) is thought by Mr Fryer tu be probably P. htterophyllns x angiistifoli'Uf. 
He writes "upper 1. ciriaceous lil>e keterophyllus but petiole shorter than 
lamina."] Sometimes (P. acuminatv.s Schum.) the midrib forms 
a long prominent point. Common in deepish water. P. VI. 
E. S. I. 
16. IP. decip'iens (Nolte) ; I. pellucid oblong rounded below not 
hooded but blunt mucronate and wavy at the end entire sessile 
or uppermost 1. sometimes subsessile, stip. not winged,' fr. 
"like that of /'. lucens," ped. equal.—,/, of B. v. t. 61. P. vii. 
35.— St. long, much branched. Ped. 1—2 in. long, thicker than 
the stem. Spikes 1—2 in. long, dense. [/'. Uicensxprr/oHutus Fryei.] 
—Canal near Bath. Forfar. Navan Canal, [ic.]. P. VII. 
E. S. I. 
17. P. longifolins (Bab. not Gay) : /. pellucid hngdnnceolate 
narrowed heXovf entire cuspidate, stip. winged, fr 
long swelling upwards, spikes with few rather whorled distant 
flowers.— i^. />. S. 2847.— St. long, slender. L. distant, iwt 
1 t cannot Cnd the wings described by Syme; nor did Mr B:ik,-r. 
V. 71. 
