[ 4 * 8 ]
f t
T E T R A N D R I A Tetragynia.
G e n . C h a r . Cal. none. Petals 4 . Style none.
Seeds 4.
Spec. C har. Leaves linear, obtufe. Stem com-
prefled.
Syn . Potamogeton compreflum. Linn. Sp. PL 183.
HudJ. FI. A n. 75* With. Pot. A r r . ed. 3 . v . a .
2 1 3 . Relh. Cant. 72.
P. caule compreflo, folio Graminis canini. Rail
Syn. 14 9 .
I N the difficult genus of Potamogeton we find it necefiary to
proceed with the utmoft caution, publifhing a fpecies now and
then as (we prefume at leaft) we clearly underftand it. That
this is the true original comprejfum of Linnaeus, as well as of all
Britilh writers, we learn from the Cliffortian Herbarium in Sir
Jofeph Banks’s poffeffion, that being in the prefent cafe the
original authority, Linnaeus having afterwards confounded with
this a very different plant, which by no means anfwers to the
character.
Potamogeton comprejfum is not very uncommon in ditches and
flow ftreams about London, and other parts of Great Britain,
flowering in June and July, when its fmall fpikes of about 4 or
more brownilh-green flowers juft emerge from the water. It
has moft affinity with P. pufillum, fee our Vol. 3, t. 215, but is
twice as large in all its parts, and effentially diftinguiflied by its
compreffed ftem ; neither do the leaves fpread fo immediately
from the bafe as in that fpecies. The root is perennial. Stem
zigzag, alternately branched, very much compreffed all the way
up. Leaves generally alternate, but the uppermoft often op-
pofite, all exadtly linear, obtufe, with a ftrong central nerve,
and 2 fine lateral ones on each fid6. Stipulae intrafoliaceous,
one to each leaf, embracing the ftem; the lower ones generally
acute and lacerated, the upper ones more obtufe and entire.
Flower-ftalk Ihort, folitary, terminal till the ftem grows
above it.