Distribution: Great Plains to northeastern United States; occasional in the Pacific Northwest.
Habitat: Wet areas.
Flowers: June - August
Conservation Status: Review Group 1 in Washington (WANHP)
Herbaceous, tufted perennial from a crown, with knotted rhizomes, the culms triangular, glabrous, 10-50 cm. tall and 0.4-1.2 mm. broad.
Leaves flat, 5-40 cm. long and 1-3.5 mm. broad; sheaths closed.
Inflorescence an ovoid to globose cluster of spikes, 1.2-3.5 cm. in diameter, the rays of the spikes 1-4, 1-6 cm. long; spikelets 15-60, compressed, oblong-lanceolate, 6-22 mm. by 2.5-4 mm.; scales 5-22, off-white to light reddish-brown, ovate-elliptic, 2.5-4 by 2-2.6 mm.; perianth none; stigmas 3; styles trifid.
Achenes dark brown to black, sessile, ellipsoid, about 2 mm. long and 1 mm. wide.