44 ENGLISH BOTANY. 
lower ones often evanescent, scarious, with a few distant slender fibres. 
Peduncles terminal between the forks of the stem and axillary, rather 
short, moderately stout, tapering towards the apex, usually curved. 
Sepals with their lamina suborbicular. Fruiting-spike rather lax, 
oblong-ovoid, few-flowered. Nuts fuscous-olive, rather large, greatly 
acuminated, compressed, curved along the upper margin, rounded 
and bluntly keeled on the back, terminated by a long slightly re- 
curved subulate beak about as long as the nut itself. Plant olive, often 
tinged with brownish-red, especially on the stem and midrib of the 
leaves, retaining its colour when dried; leaves slightly shining. 
In ditches and ponds. Very common, and generally distributed, 
except in the extreme north of Scotland. 
England, Scotland, Ireland. Perennial. Summer. 
Stems branching as in P. perfoliatus. Leaves 1 to 3 inches long, 
remarkably undulated at the margins and tinged with reddish-brown, 
so that the plant may be very readily recognised. Fruiting peduncles 
1 to 4 inches long. Fruit very different from that of all the other 
species, about 4 inch long, but half of this length is occupied by the 
beak. 
The young state of this plant is the P. serratus of Hudson; it is 
very unlike the ordinary form, and might easily be passed over as 
P. obtusifolius, but the leaves are more or less serrulate. A speci- 
men of the ordinary form gathered late in August had thrown out 
numerous branches of P. serratus from its rootstock, so it cannot be 
considered as even a variety. 
Curled Pondweed. 
French, Potamot crépu. German, Krauses Samkraut. 
Secrion I].—OPPOSITIFOLII. 
Leaves all similar and opposite, sessile and amplexicaul, ovate or 
lanceolate, with involute vernation. Stipules absent, except at the 
base of the peduncles. Peduncles terminal. Spikes few-flowered, 
very short, dense. 
SPECIES XV.—POTAMOGETON DENSOS. Lin. 
Pirate MCCCCXIII. 
Reich, Ic. Fl. Germ. et Helv. Vol. VII. Tab. XXVII. Figs. 46 to 49. 
Billot, Fl. Gall. et Germ. Exsice. No. 2552. 
Stems rather slender, sparingly dichotomously branched. Leaves 
all submerged and translucent, opposite, amplexicaul, folded’ longi- 
tudinally and recurved, ovate or lanceolate, acuminate, finely serrulate 
