54 ENGLISH BOTANY. 



the upper margin, with the lateral keels more prominent than the 

 central one. 



Var. a, gemdnus. 

 Plate MCCCCXXII. 

 Beich. Ic. Fl. Germ, et Helv. Vol. VII. Tab. XIX. Fig. 30. 



Leaves and branches rather few and distant, nearly equally disposed 

 over the stem. Leaves all similar, the early ones 1-ribbed. 



Var. 3, scoparius. Wallr. 

 Plate MCCCCXXIII. 

 Rntl. Ic Fl. Germ, et Helv. Vol. Vll. Tab. XIX. Fig. 32. 

 P. marinus, Iluds. Fl. Angl. ed. ii. p. 77 (non Linn. Herb.). 



Stem at length nearly bare of leaves and branches below, very 

 leafy and much branched towards the apex at the time of flowering. 

 Early leaves flat, 3-ribbed ; upper leaves setaceous, 1-ribbed. 



Var. a in lakes and ponds, in fresh water. Frequent in England. 

 Rare in Scotland, where I have gathered it in Duddingston Loch, 

 Edinburgh, Loch Gelly and Camilla Loch, Fife, and Orphir Loch, on 

 the mainland of Orkney, and I have specimens from between Troon 

 and Ayr. 



Var. 3, in brackish ditches. Apparently confined to England, 

 where it is very plentiful in the south, and whence I have seen sjje- 

 cimens as far north as Coatliam, Yorkshire, and Rhyl, Flint. One or 

 both of the forms are frequent in Ireland. 



England, Scotland, Ireland. Peremiial. Summer. 



A variable plant, with the upper leaves much narrower than those 

 P. flabellatus, and composed of two united parallel tubes divided by 

 transverse partitions. The early leaves, however, though much nar- 

 rower than those of P. flabellatus, are sometimes very similar to the 

 later leaves of that plant. The Iruit is rather rounder, and has the 

 lateral keels more developed, and the central one usually indistinct. 

 The spike is generally shorter, and with the flowers more crowded 

 towards the apex. The whole plant is also more deeply tinged with 

 olive-brown. 



The P. marinus of Hudson seems to be P. eu-pectinatus, var. 

 scoparius, as that is the only form which grows in Sheppey, where it 

 is very abundant : this form connects var. a with P. flabellatus. 



Fennel-leaved Pondweed. 



French, Potamot en dents de ^peigne. Gei-man, Fadenhldltriges SatnJcraut. 



