226 E. Tuckerman on New England Plants. 
elongatis linguiformibus acuminatis ; pedunculis ey we fruc- 
tibus recentibus oblique eoratis breviter recurvo-rostratis dorso 
arcuato rotundatis, lateribus convexis in faciem cameos de- 
elivibus. 
Has.. Ponds; Cambridge and elsewhere, very common in 
New England, and I have seen it from*’New York. FJ. June, 
July. “Fr. July, Aug. Stem simple, terete, enclosed by the clasp- 
ing stipules, 2-5 feet long, Floating leaves oblong-lanceolate, 
the base often ovate and subcordate, marked on the under side 
with 6-8 prominent nerves, 3~5 in. long, by 14 to 1} in. wide, 
on channelled petioles, of whieh the u permost are mostly shor- 
ter than the blade.: Submersed leaves delicate, pellucid, broad- 
lanceolate, acute at’each end, more or less re curved and sick 
shaped, 6-8 nerved, obsenrely but closely netted-veined, 5-8 in. 
long, by 14 to 2 and more in width, on conspicuous, channelled, 
and in the care elongated petioles. a 1on8 (the up- 
rmost n.) acuminate, inclosing the stem. | Pedun- 
cles much ~ostinintl often more than twice the size of i stem, 
longer than the elongated spike. Nutlets not very obliquely ob- 
ovate, slightly beaked, rounded on the back. The rather thin 
exocarp being removed, the back appears: rounded-carinate, with 
a sunken line on each side. Putamen thick, spongy. Seed con- 
volute-uncinate. 
P. lonchites, (Sp. nov.): a gracili ramoso ; foliis submer- 
sis membranaceis, superioribus breviter petiolatis reliquis sessili- 
bus, elongatis lanceolato-linearibus basi attenuatis acuminatis ner- 
om vis 6-8 prominulis omnibus undulatis petiolis supra planis, infimis 
; longe mucronatis s. in subulas rigidiusculas acuminatas abeunti- 
"4 bus ; natantibus»chartaceis membranaceisve ovatis ovalibus lan- 
ceolatisve apice plus minus attenuatis undulatisque petiolis supra 
Planis ; stipulis gracilibus lineari-linguiformibus obtusis ; pedun- 
fructibus recen- 
tibus oblique obovatis vix lenatis compressiusculis obsolete tri- 
carinatis rostello brevi truncato terminatis, dorso acutiusculo, lat- 
eribus 1 in faciem acutam declivibus. 
az. Rivers; in the Charles on. Newaen and Natick. Fv. June, 
Jaly. Fr. July, Aug. Stemslender, terete, much branched, elon- 
gated, (3-6 feet long.) » ‘Submersed leaves lanceolate-linear, ta- 
pering at the base, long-acuminate oa often a little faleate above, 
undulate, with 6-8 scarcely prominent nerves, loosely netted- 
veined, 5-10 inches eee by 3-6 Tess in width. Floating 
leaves ‘delicate, papyraceous, or often, and especially the lowest 
_membranaceous, always.more or less tapering and waved above, 
_ With about 6 prominent .nerves on the under side, either shorter 
__ and the base more or — ovate (2-3 in. long by about 14 in. wide), 
_ = elongated-lanceolate (4-5 in. long by about 1 in. wide), the 
___ petioles rather clongated, flat and one-furrowed above. — Stipules 
* 
