Distribution: Occurring on both sides of the Cascades crest in and in the Columbia River Gorge in Washington; southern British Columbia to California, east across much of North America to the Atlantic Coast.
Habitat: Pond and lake shores, streambanks, seeps, vernal pools, and ditches at low to middle elevations.
Conservation Status: Not of concern
Tufted annual, the triangular, solid, stout stems 1-7 dm. tall.
Leaves grass-like, crowded near the base, the elongate blade 2-9 mm. wide, the sheaths closed.
Inflorescence of clustered, cylindrical spikes, the terminal cluster sessile, the others on rays up to 7 cm. long, each spike 1-4 cm. long, with numerous, spirally arranged spikelets on an elongate rachis; scales of the spikelets in two vertical rows, 1.2-1.5 mm. long, with a green keel, closely set; perianth none; stamens 3; style trifid.
Achenes unequally triangular, 0.7-1.0 mm. long, pale and shining.