Cyperus lupulinus

Cyperus lupulinus, the Great Plains flatsedge, is a plant species native to North America. It is widespread across southeastern Canada and the central and northeastern United States as far west as Wyoming, Colorado and New Mexico, with more isolated populations reported in Washington (Asotin County), Idaho (Idaho County) and Oregon (Wallowa County). It grows in open, sun-lit locations such as fields, prairies, roadsides, farms, etc.

Two subspecies are accepted:

Cyperus lupulinusis a perennial herb up to 50 cm tall, spreading by means of underground rhizomes. Culms are triangular in cross-section. Spikes are densely clustered into a more or less spherical clump. Achenes are dark brown, almost black, egg-ehspaed, about 2 mm across