_ 
B. Tuckerman on New England Plants. 227 
“eh a Spikes slender, on elongated, thickened 
Nutlets small, obovate, scarcely lunate, obscurely 
cert terminated by a short, truncate beak. ‘This handsome 
species is extremely abundant in Charles river. Though near to 
P. heterophyllus of authors, (P. gramineus, F'r., Koch.) it appears 
to be distinct from my numerous European specimens of that 
species, as well cs from perfectly corresponding American speci- 
mens, from the lakes of Western New he inthe Herbarium 
of Dr. Gray. 
P. Claytonii, (‘Tuckerm. ): caule socalled foliis sub- 
mersis membranaceis gramineis elengatis linearibus acutiusculis 
basi vix attenuatis 5-nervibus sessilibus ; natantibus coriaceis 
crassiusculis angustatis ellipticis obovatisve — ie ere 
compressis; stipulis linguiformibus ‘acutis; pedunculis teretibus 
eequalibus breviuseulis ; fructibus recentibus ir a oboe tri- 
carinatis, carina media acuta superne gibboso-alata, lateralibus dis- 
tinctis obtusis, stigmate subapicali, lateribus convexiusculis, facie — 
— P. Claytonii, Tuckerman Obs. in Sill. Journ., xiv, 
38. P. fluitans, Pursh! Fil. 1. p. 120. ees Fl. Bost. 
S. 
ee 
edit. 2: p. 63, e deser. Torr. Fl. U. S. -p. 196, e des 
Has. Ponds, rivers, and ditches in meadows, common in New 
England, and extending southward to Virginia! Stem compress- 
ed below ; branched, in wholly submersed, sterile plants from be- 
low, in fertile —_ especially from above, and bearing often nu- 
merous (8-12) spikes; 2—5 feet long. Submersed leaves grass- 
like, linear, a little tapering at base, and very slightly so above to ? 
the obtusish tip, about 5-nerved, the space *between the midrib | 
and the nearest lateral nerves on either hand remarkably cellulose 
reticulate (as observed by Chamaisso, cited below), 5-8 inches long. 
Floating leaves rather small, thickish, narrowed, tapering to the 
commonly short petiole, marked on the under side with about 
141 snaeeemen us; impressed nerves, the petioles compressed, flat- 
ish an e-furrowed above. Stipules short. Peduncles of the 
f the stem, rather short, often of about the length of the 
cylindrical spikes. Nutlets obovate, the sharp keel abruptly alate 
above and sloping suddenly toward the style, lateral keels obtuse, 
“ sides when dry impressed in the middle. Exocarp thickish 
as the rather thin and hard putamen thickened above. 
Seed aliliaieeostvalte. I have found this species in its most 
perfect state, in which the whole plant is of a bright grass-green, _ 
only in ponds. Smaller, more or less fuseescent forms are-com-  _ 
mon in ditches, as well.as a wholly submersed, sterile state, with 
a little of the habit of P..compressus. ‘To the trae Wet od 
of that species, the present one, though its (necessary) ae” 
leaves compel it to assume avery different habit, _ probably near 
A similar change of habit is seen in the Sin with leave 
of the next.species. Poiret (Ene. Si he” 534,) under P. oe 
ih * 
¢ 
