472. TETRANDRIA TETRAGYNIA, Potamogeton. 
water much shorter than the leaves.—Stipules solitary, axillary, 
sheathing, length of the petioles, slit balfway or more on the inside. 
— Peduncles. solitary, axillary, or opposite to, a leaf, round, rather , 
thicker, smooth, aud nearly as long as the cylindric spike, which 
each supports.— Flowers small, numerous, green.— Calyr- none 
Petals \ong-clawed, nearly round, incurved, fleshy ; concave within, > 
convex on the back, permanent.— Filaments none. Anthers, four 
pairs attached to the claws of the petals on the inside.—Germs four, 
- ovate-oblong, one-celled, with one ovula in each. Styles short, and 
thick. — Stigmas a dark speck on the apex of the styles.— Drupes 
obovate, smooth. Nut conform to the drupe, one-celled.— Embryo 
curved, as represented by Gartner in P. natans, vol. ii. t. 84. ` 
2. P. tuberosum, R. 
© Leaves alternate, and only opposite at the floriferous forks, sessile, 
linear, much waved, entire, clear, when dry membranaceous. ‘i 
Found immersed in extensive masses, in Ponds, "Lakes, and 
receptacles of fresh water in Bengal, during the dry season, chiefly 
when in flower in February, it rises so near to the surface as to 
allow the little spikes of flowers to emerge completely. 
Root of long simple fibres, brown, &c. according to the colour. 
of thé mud they enter; ou the creeping joints are generally found 
small roundish-lobate, viviparous tubers.— Stems aud branches of: 
various lengths, according to the depth of the water, &c. a groove 
on each-side gives them the appearance of being compressed, thick. 
as a pack-thread, smooth, at the bottom of the water creeping, 
towards the extremities when in flower dieliofamoilh s previously. to 
that period the branches are alternate and axillary.— Leaves sessile, 
alternate, except at the flor iferous fork of the branches, where they 
are opposite, linear, rather obtuse, much waved, finely and acutely 
serrulate, with two slender nerves near the margin, pellucid, from 
two to three inches long, by little more than a quarter of an inch 
broad.—Stipules sheathing, short, smooth, greenish like the other 
parts of the Plant, and scarcely to be distinguished from them.— 
