Distribution: Chiefly west of the Cascades in Washington, but also in Chelan, Yakima and Pend Oreille counties; British Columbia south to California, east to Idaho, Montana and to the eastern half of North America.
Habitat: Wet meadows, marshes, and shores of ponds and lakes.
Conservation Status: Not of concern
Annual, perennial herb, up to 1 m, rhizomes long; stems not triangular but cylindric, hollow.
Cauline, 3-ranked, proximal bladeless; blade up to 15 cm x 3-8 mm, flat; sheath not splitting, parallel venation, green.
Spikes number 1-17, from sheaths of bladed leaves, 6-30 cm; spikelets generally arranged in head, spike, raceme, or panicle-like inflorescences, spikelets number 3-10, 1.5-3 cm x 1.2-2.5 mm, flat; bracts 2-ranked, numbering 4-8, 3-9.5 mm long, lanceolate-linear, veined, each with 1 flower in axil; flowers bisexual; perianth bristles number 6-9, approximately 5mm; stamens 3, anthers attached at base; style 2-branched, base persistent.
2-4 mm long, ellipsoid-linear, flat, yellow.