Culms 20-80 cm. Leaves 1-3.3(-3.8) mm wide, widest leaf (1.7-)2.3-3.3(-3.8) mm wide. Inflorescences very dense, 1.2-2.5(-4) cm; distance between basal 2 spikes usually less than length of basal spike. Perigynia usually 2-12-veined adaxially over achene, (3.1-)3.5-4.75 mm, margins usually not serrulate.

Fruiting late spring-early summer. Coastal bogs, swamps, stream and lakeshores; 0-200 m; B.C.; Alaska, Calif., Oreg., Wash.