2848
POTAMOGETON plantagineus.
Plaintcoin-leaved Pondweed.
TETANDRIA Tetragyriia.
Gen-. Char. Flowers sessile upon a spike that issues
from a sheathing bractea. Perianth single, of
4 scales. Anthers sessile, opposite to the scales
of the perianth. Pistils 4, which become 4
small nuts. Embryo curved.
Spec. Char. Leaves all membranous, stalked, rather
opake, blunt, entire ; lower ones oblong ; upper
elliptical. Nuts minute, obliquely-ovate, rounded
on the back (when fresh). Spike slender, cylindrical,
densely-flowered, on a long terete peduncle.
Potamogeton plantagineus. Ducros in Gaud.
FI. Helv. v. 1. 471. t. 3. Poem, and Schult.
v. 3. 504. Reich. E x cu rs: 9. Bert. FI. Ital.
' v. 2. 232. Bluff, and Fing. ed. 2. 268. Bab.
Prim. FI. Sam . 99.
P. coloratus. Hornem. Fl. Dan. 1449. Cham,
in Linncea, v. 2. 194. t. 5. ƒ. 15.
P. Hornemanni. Meyer Chi. Hanov. 521. Koch
Syn. 674.
S t em creeping below, sometimes sending out long scions
from its upper axils, cylindrical, contracted at the joints,
striated. Leaves oblong-ovate or lanoeolate, alternate, on
long stalks, the upper ones ovate, or even orbicular, or cordate,
and sometimes nearly sessile, opposite, all obtuse,
membranous, entire, not at all coriaceous, many-nerved
and beautifully reticulated with transverse veins, the nerves