Rhizomes 1-2 mm thick. Culms 10-30(-40) cm × 1-2(-3) mm. Leaf blades 1-3 mm wide. Spikes 6-17 per culm. Spikelets 1-7 per spike. Anthers (1.5-)1.8-2.6(-2.8) mm. Fruiting summer-fall. Stream shorelines; 0-100 m; Que.