NAIADACEZ. 39 
the leaf serrulate, especially towards the apex. Peduncle twice as long 
-as the spike or more. 
Var. y, decipiens. 
Pratt MCCCCIX. 
Reich. Ic. Fl. Germ. et Helv. Vol. VII. Tab. XXX. Fig. 163. 
P. decipiens, Nolte. Baker and Trimen, in Seemann’s Journ. Bot. 1867, p. 71. Bab. 
Man. Brit. Bot. ed. vi. p. 364, Fries, Summ. Veg. Scand. p. 68 (67). Koch. 
Syn. Fl. Germ. et Helv. ed. ii. p. 779. Reich. l.c. p. 63. 
Leaves indistinctly stalked, oblong-oval or oblong-obovate, apiculate 
or shortly cuspidate, entire on the margins or subserrulate only at the 
‘apex. Stipules much smaller than in vars. « and #, and with the wing 
less prominent. Peduncles not more than twice as long as the spike. 
In ponds and slow streams. Rather common, and generally dis- 
‘tributed in England, and the southern half of Scotland, but absent 
from the north of the latter country. Frequent throughout Ireland. 
Var. 6, in deep water. Var. y, canal at Bath. 
England, Scotland, Ireland. Perennial. Summer, Autumn. 
The largest of the British pondweeds. Stems often more than a 
yard long, and the leaves from 3 to 10 inches, by 1 to 2 inches broad, 
with a thick midrib and lax areolation. The stipules of the upper leaves 
9 
are frequently 2 or 3 inches long, and have 2 or 3 prominent wings 
on the back; the peduncles are 2 to 6 inches long, thicker than the 
stem. The fruiting-spike 1} to 3 inches. Nuts larger than in any of 
the previous species of the genus, except P. natans. 
The plant figured by Reichenbach as P. lucens, var. coriaceus, of 
Nolte, ] have not seen. Mr. William Wilson found a form in Anglesea 
with floating leaves, the lamina about 2 inches long, and the petiole 
about an inch; but they are not distinctly coriaceous. 
The var. 6 is remarkable for the midrib of the leaf running out beyond 
the point. The leaves also are usually longer and narrower than in 
var. «, and the peduncles, which are rarely produced, are much longer, 
often 5 or 6 inches. 
Var. y (for fresh specimens of which J am indebted to Mr. C. E. 
Broome, and for dried ones to Mr. T. B. Flower and Mrs. Hopkins, 
the latter under the manuscript name of “ P. Burtoni”) appears to be 
a weak state, in which the plant has been injured, and has thrown out 
numerous fresh branches. ‘The leaves are rarely above 3 inches long. 
The stipules are frequently not more than } inch, and with the wings 
much fainter, although they are present in all the specimens I have 
examined. The fruit is apparently always abortive. Some stress is 
laid on the fact of the margin not being denticulate; but so far as I 
can judge there are always a few denticulations towards the apex of 
the leat. There are certainly such in the specimen of P. decipiens 
