40 ENGLISH BOTANY. 



in Fries' Herbarium Normale at Kew, and in the Bath plant they are 

 very conspicuous towards the apex of some of the leaves, and nearly 

 absent in others. 



Great Pondweed. 



French, Potamot luisant. German, Sjncgelndes Samkrauf, TriigenscJics Sanikrcmt. 



SPECIES (?) XI.— P OTAMOGETON "LONGIPOLIU S." 



Gay. Bab. 



Plate MCCCCX. 



Bekh. Ic. Fl. Germ, et Helv. Vol. VII. Tab. XL. Fig. 70. 



Bab. in Engl. Bot. Suppl. No. 2847. M<an. Brit. Bot. ed. vi. p. 364. 



P. macrophyllus, Wolfg. in B,dm. et SchuUes Mant. p. 358. 



Stem stout, sparmgly branched, the lower branches barren. Leaves 

 all similar, the lower ones alternate, the upper opposite, submerged, 

 sessile or subsessile, not amplexicaul, ascending, flat, long, strap- 

 shaped, gradually attenuated at the base but with scarcely any petiole, 

 acute, mucronate, not hooded at the apex, not serrulate at the margins, 

 translucent, with several longitudinal ribs connected by numerous 

 ascending (?) transverse veins. Stipules rather small, "green, lanceo- 

 late, with 2 narrow wings on the back" (Bab.). Peduncles terminal ( ?), 

 long, very stout (thicker than the stem), slightly thickened towards 

 the apex. Fruit (of the Irish plant) unknown. 



A single specimen, gathered in deep water. Loch Corrib, Galway, 

 by Mr. John Ball, m 1835. It has not been found since. 



Ireland. Perennial. Autumn. 



Of this plant I have never seen British specimens. Judging from the 

 figure in " English Botany Supplement," in which the leaves are re- 

 presented as partially clasping, and from the very long peduncle, 

 (G inches long), I was incluied to believe it a form of P. prajlongns. 

 But Professor Babington has kindly examined his Irish specimen, and 

 thus writes : — " I do not tliink that this is P. prajlongus. It does not 

 seem that even the floral leaves are really amplexicaul, as they appenr 

 decidedly narrowed to their base, and those of the branches have 

 mostly very short stalks, nor is their tip hooded, as I have always 

 ibund it to be in true P. prajlongus, but terminates in a point, like 

 tliose of P. lucens. It seems also to have the winged stipules of that 

 plant, but its leaves are not mutually denticulate. It is Reich. Fl. 

 Germ. Exsicc. No. 2501." 



P. longifolius. Gay., of Avhich there are numerous French specimens 

 in his herbarium, has the leaves more narrowed towards the base than 

 in the " Engl. Bot. Suppl." figure, but is probably the same. In the 

 continental plant the peduncles are sometimes long, sometimes short ; 



