35 
LHemicarpha micrantha Britton, Bull. Torr. Club, xiv. 104 (1888). 
Type specimen the same as that of Scirpus micranthus. 
Plant annual, with fibrous roots, glabrous throughout; stems 
closely tufted, slender, erect, or in the smaller, more broadly 
tufted plants recurved-spreading, 2.5 to 20 cm. high, simple, 
terete, glabrous, striate, nodeless; radical leaves 1 or 2, the upper 
with a membranaceous, purplish or brownish sheath 4 to 20 mm. 
long, closed to near the apex, the blade 25 mm. or less in length, 
sometimes obsolete, flat and 0.5 mm. wide, or much narrower and 
filiform ; lower leaf reduced to a bladeless sheath similar to the | 
upper, but smaller, or entirely wanting ; inflorescence a cluster of 
I to 3 (usually 2) spikes at the apex of the stem, each subtended 
by a leaf; lowest leaf of the inflorescence erect, appearing like a 
continuation of the stem, commonly 5 to 20 mm. long (rarely in 
slender specimens reaching 100 mm.), the short, half-clasping base 
with membranaceous margins, the blade similar to that of the 
radical leaf; second and third involucral leaves similar to the low- 
est, but much smaller and divergent; spikes sessile, ovate to ovate- 
lanceolate, commonly 2 to 3 mm. (rarely 5 mm.) in length, usually 
acute, bearing innumerable scales on a cylindrical axis; bractlet 
about 1 mm. long, brown, with a green excurrent midrib, oblong- 
obovate, abruptly acute; perianth consisting of a single, minute, 
obsolescent, hyaline scale opposite the bractlet, discernible only in 
the flowering spike; stamen 1, opposite the axis of the spike; 
Pistil with a well-defined style and 2 spreading, filiform stigmas; 
achenium brown, rarely black, subterete, clavate to narrowly 
oblong-obovate, 0.6 to 0.8 mm. long, the color half obscured by 
the air-filled, minutely and regularly cellular-punctate outer seed- 
coat. 
This plant has a wide distribution on our continent, occurring 
in both North and South America. Specimens have been exam- 
ined by the writer from Massachusetts, Rhode Island, New York, 
Pennsylvania, Wisconsin, Michigan, Kentucky, Florida, Nebraska, 
Indian Territory, Texas, New Mexico, Arizona, Washington, Cali- 
fornia, Mexico, Guatemela and Brazil. As might be expected of 
a plant of such broad range, it shows marked variation, but in all 
those specimens which we have referred to the type form of the 
Species, this variation appears to be essentially one of size and 
external form. The plant of the Gulf and southern Atlantic states ; 
is commonly § to 10 cm. high and nearly erect. Toward the 
Northern limit of its range, both in the state of Washington, on 
the Pacific coast; in Wisconsin, in the interior of the country; and 
in New England, on the Atlantic coast, the specimens beco 
