POLYGONACEOUS GENERA. 47 
beneath and the margins with some scattered bristly hairs; 
foliage widely spreading. 
Riparian state ? (provisionally P. NWebrascensis). Leaves as- 
cending, more remote, distinctly short-petioled, the internodes 
twice the length of the sheaths, the rim of the latter quite 
narrow ; peduncle of the short oblong spike with a few delicate 
gland-tipped hairs, bracts thinly somewhat hirsute-hairy. 
The terrestrial type is known to me only as collected by my- 
self on the open prairie at Prairie Junction in southeastern 
Minnesota, 7 July, 1898. Itis exceedingly well marked in habit 
and foliage, much resembling some alternate-leaved asclepiads. 
The riparian plant, very likely distinct, is typified in Mr. Ryd- 
bergs’ n. 1649 from central Nebraska, as in U. S. Herb. 
P. AMMOPHILA. Terrestrial, and even of rather dry sandy 
soil. Decumbent stems a foot or two long in fertile plants and 
loosely leafy, lower, with short internodes and a dense leafiness 
in the sterile state : leaves lanceolate, 3 to 5 inches long, acute, 
only the uppermost with midvein hirsute beneath, this in the 
lowest quite glabrous and the leaf-surface scarcely roughened 
with scattered hair-points, ocreæ with very thin villous sheath 
and broad toothed and bristly-ciliate border : spikes mostly 2, 
oblong, their peduncles beset with a few short gland-tipped hairs 
and fewer long bristly ones; bracts hirsute-ciliate, otherwise 
nearly glabrous: achenes small, somewhat obovate, black and 
shining. 
The fertile type of this has been sent me {by Mr. Holzinger 
from Winona, Minn., where he collects it on high sandy banks 
of the Mississippi. Sterile specimens were taken by myself on 
dry sandy banks of the same river, at LaCrosse, Wis., 8 July, 
1898, 
P. MURICULATA. Stout, decumbent, the somewhat branching 
stems 2 feet long, densely leafy, with a foliage at length widely 
spreading, the internodes barely an inch long and nodes swollen: 
leaves elliptic-lanceolate, 4 or 5 inches long including the short 
stout petiole, merely acutish at both ends, sparsely scabrous and 
strigose above, marginally short-ciliate with appressed setose 
