7 
That 
* 
sagt 
E. Tuckerman on New England Plants. 229 
compressis subtricarinatis, dorso deorsum curvato alato-carinato 
dentibus elevatiusculis cristato, carinis lateralibus rotundatis, late- 
ribus sulco ome impressis, stigmate faciali sessili, facie — 
tundata. 
Has. Rivers ers; common in the Charles and in the Mystic, oF 
also in the Middlesex canal. Stem slender, compressed, and-con- 
cave-convex below, much branched, 6 to 12 inches long. Sub- 
mersed leaves delicate, pale-green, grass-like, eonnate with the 
stipules and sheathing, linear, obtuse, 13 in. long, by 4-% lin. 
wide, Floating leaves coriaceous, oblong lanceolate or linear, 
the last often a little faleate, furrowed on the under ‘side with 
3-7 impressed nerves, half an inch to an inch long and 2-4 lines 
wide, on channeled ‘petioles 3-5 lines long, which are connate 
with the stipules the lower near the middle of the stipules, the 
r below it. Stipules of the submersed leaves reduced to 
short, lacerate ligules. Submersed spikes on very short, erect- 
ish, clavate peduncles, 2-6 flowered ; spikes of the floating part 
ater, cylindrical, on peduncles half an inch or more in length. 
Natlets green, lentiform, and in perfect specimens rendered obo- 
vate by the broadly alate-carinate: back, which is crested with 
about 5 prominent, rather distant teeth; the lateral keels rounded : 
the sides conspicuously cochleate.* Exo carp membranaceous, 
produced on the back, and forming the wing: Putamen several 
times thicker, but semitransparent. Seed cochleate. This curi- | 
ous species, which is recognizable by its pale-green color and del- 
icate, grass-like leaves, is more common, in this neighborhood at 
ow- 
tirely resembles in habit P. hybridus, from which it differs in its 
grass-like leaves evidently connate with the stipules, in the attach- 
ment - the petioles of its floating leaves to the stipules, in its 
nt nutlets, &c. The following description of the 
from living ‘specimens, will afford a fuller com- 
ese nearly allied plants. P. heterophyllus? Ell. 
tos 
seems to accord in'many respects win the species 
erized. 
Ms ¢ Michx.): caule comipresso striato, ramoso ; foltis — 
BN Aa eis tenuissimis cum stipulis eonnatis oa 
nantibusque setaceo-linearibus, apice attenuatis acutis, 
bus ; natantibus subcoriaceis ovalibus lanceolatis Tineatibtory sf 
— hand rat aed stipulis nervosis ; spicis partis in See : 
agenscond 
wh * The spiral eae ‘Of ae sides of t 
when and reminds one of e outli val 
Sel ine 0 Pa smal pf a 
a Serizs, Vol. VI, No. 17.—Sept., 1848. 
* 
