Distribution: Widespread in the northern hemisphere; found throughout the Pacific Northwest.
Habitat: Marshes and other wet places, from sea level to moderate elevations in the mountains.
Flowers: June - September
Conservation Status: Not of concern
Tufted annual, 0.5-5 dm. tall, the culms 0.5-2 mm. thick, with many ribs.
Leaves all basal and reduced to sheaths.
Spikelet terminal and solitary, 5-13 mm. long, ovoid, many-flowered, usually over 40; scales spirally arranged, 1.7-2.5 mm. long, purplish or brownish, with greenish mid-strip and paler, translucent margins, the lowest one sometimes empty; perianth bristles 6-7, brownish, about equal to the achene, or wanting; stamens 3; style usually bifid, thickened at the base.
Achenes lenticular, 1.0-1.5 mm. long, including the flattened tubercle, which is appressed to the summit of the brown, smooth and shining body of the achene.