30 LEAFLETS. 
southeastern Wyoming, July, 1894, A. Nelson. The description 
is drawn from two sheets in my herbarium, bearing the collec- 
tor’s numbers 479 and 551, a duplicate of n. 551 also in U. X. 
Herb. A fourth sheet I have seen in Herb. C. F. Baker, obtained 
by Mr. Nelson from ponds along the river at Dunn’s Ranch, 
Albany Co., Wy., 16 July, 1900, and numbered 7598; this quite 
like the others except that it is glabrous altogether. Another 
specimen in Mr. Baker’s herbarium, collected by himself at Fort 
Collins, Colorado, in 1894, has a scabrous peduncle and leaves 
marginally serrulate-scabrous without other pubescence, while 
one in Mr. Osterhout’s collection from the same region is glab- 
rous except as to the peduncle. Another Colorado specimen I 
have that was obtained by myself on Clear Creek, a tributary of 
the Platte, in 1870. But Ido not feel very confident that all 
these are part and parcel of P. Plattensis; nor do I feel sure 
that the floating-leaved plant which I have appended as an 
aquatic phase of it really is such. This is Mr. Nelson’s n. 7465 
from Dunn’s Ranch, July, 1900. Field study alone can enable 
one to decide. 
P. SUBCORIACEA. Aquatic. Stems short, with internodes of 
of an inch long, apparently submersed in shallow water ; float- 
ing leaves subcoriaceeus, oblong, obtuse at both ends, 2 to 22 
inches long, on firm petioles of ł inch: spike solitary, ovoid, 
hardly an inch long, on a stout peduncle of an inch or more: 
achenes small, round ovate, polished but with an obvious scarcely 
definable unevenness. 
Riparian state. Foliage much larger, not as firm in texture, 
oblong-lanceolate, acute, subcordate, about 4 inches long and 
about 2 in breadth, on petioles of 24 inches, both faces glab- 
rous, but those smallest and near the spike distinctly though 
minutely scabrous-serrulate without trace of other pubescence: 
spike oblong, not longer than in the aquatic state but on a much 
longer and notably glandular-hispid peduncle. 
This very satisfactory species rests at present on a single good 
sheet in U. S. Herb., from the North Fork of Laramie River, 
Wyoming, twelve miles from Laramie Peak, collected by Charles 
Schuchert, 24 Aug., 1899. The firmness of the foliage in the 
aquatic, and the serrulate margin of the uppermost riparian 
