CLASS IV. OKBEKlU.j POTAMOGETON. 211 



lanceolate, pointed, with from five to seven lateral parallel veins, 

 springing from the midrib. 



English Botany, t. 376. — English Flora, vol. i. p. 232. — Hooker, 

 British Flora, vol. i. p. 76. — P. Pro'tetis, Lindley, Synopsis, p. 250. 



Leaves on short footstalks, alternate below, frequently opposite above, 

 slightly waved, entire, frequently tapering into a rounded footstalk at 

 the base, well distinguished by the numerous transverse connecting 

 veins, uniting the five or seven main ribs. Stipula large andfoliaceous. 

 Stem long, round, scarcely branched. Sj)ike about two inches long, 

 crowded, of a green colour, supported on a strong peduncle, mostly 

 thickened upwards. 



" The largest of our species, and very beautiful in the nervation of 

 its leaves. Chamisso and Schlechtendal include this in a division of 

 the genus which has sometimes floating and coriaceous leaves (folia 

 accessoria), as it is found by Mr. Wilson at Lyn Maclog. They change 

 its name to P. Proteus, and consider the P. heterophyllus a variety of 

 it. To me they appear distinct ; but aquatic plants of all kinds are 

 extremely liable to vary." — " Coriaceous leaves rare, ovato-lanceolate, 

 moderately acute, less evidently stalked than in P. heterophyllus ; 

 foliage more crowded, and stipules larger and (in proportion) narrower, 

 than in that species. Spikes twice as long." — Wilsoti, Hooker^ s British 

 Flora. 



Habitat. — Lakes, ponds, and ditches ; common. 



Perennial ; flowering in June and July. 



10. P. prmlon'gtis, WulfT. (Fig. 274.) long-stalked Pondweed. Leaves 

 oblong, principal nerves three, connected by reticulations with 

 several lesser ones ; peduncle long. 



Hooker, British Flora, vol. i. p. 77. — Cham, in Linnea?, vol. ii. p. 

 191.— Rich. Jconogr. t, 185. 



Leaves invariably oblong, obtuse, also distinguished by the lateral 

 parallel nerves springing from the base, where they clasp the stem, 

 and by the lengthened peduncle. In size it is nearly equal to P. lucens. 



Habitat. — Lakes and pools. Moss of Litie, Nairnshire; Bgi'wick- 

 shire ; Brechan. 



Perennial ; flowering in July. 



***** Leaves alternate; upper ones floating, broader than the rest 

 Stipules free. 



11. P. heterophyl'lus, Schreb. (Fig. 276.) various-leaved Pondweed. 

 Upper leaves elliptical, stalked, floating; lower ones lanceolate, 

 sessile ; flower-stalks swelling upwards. 



English Botany, t. 1285.— English Flora, vol. i. p. 229.— Liudley, 

 Synopsis, p. 250. — Hooker, British Flora, vol. i. p. 77. 

 Upper or floating ^aii'CA' often absent (Wilso7i), mostly tinder two 



