2609
P O T A M O G E T O N acutifolius.
Sharp-leaved Pond-weed.
TE TR AN D IIIA Monogynia.
Gen. Char. Pet. 4. Cor. none. Seeds 4, naked,
sessile.—Sm.
Spec. Char. Leaves all submersed, linear, acuminate,
with three principal and numerous close, parallel,
intermediate nerves occupying the whole
surface. Spikes oval, compact, about equal in
length with the short peduncle.
Syn. Potamogeton acutifolius. Link in Poem. 8g
Schultes Syst. Veget. v. 3. 513. Mert. % Koch.
Deutsch. FI. v. 1. 854. Reich. Iconogr. 1 .176.
(excellent.) Cham. 8g Schlech. in Linnwa. v. 2.
180. t. 4 ; /. 10.
C h AMISSO and Schlechtendal, in an excellent Memoir
on the Alismaceie found daring the Russian voyage of discovery
that was undertaken at the cost and under the direction
of Count Romanzoff, have given a new arrangement
of the genus Potamogeton, and have shown that the nerves of
the leaves, especially in those whose leaves are linear, afford
excellent characters. Guided by this rule, which, as
far as our observations have gone, seems to be a very important
one, those authors have referred the P . compres-
sum of Engl. Bot. t. 418. to P . pusillus, a variable species
indeed, but distinguished by its 3—5-nerved leaves,
with only a few central intermediate ones. Two species,
natives of Britain, allied to this in habit, are remarkable
for having, besides the 3 principal nerves, numerous other
intermediate ones or strice occupying the whole surface. Of
these again one, P . zosterijolius of Schumacher, [P. cuspida-
tum of Schrader and Engl. Flora,) is distinguished by its