Plants loosely cespitose; rhizomes horizontally spreading, brown to reddish brown, 20-70 mm, slender. Culms 13-50 cm, scabrous distally; bases (remnants of old leaves) weakly to strongly fibrous. Leaf blades green, 0.7-4.5 mm wide, herbaceous, smooth to scabrous abaxially, smooth to scabrous adaxially. Inflorescences with both staminate and pistillate spikes; peduncles of staminate spikes (0.8-)2.5-20 mm; proximal cauline bracts leaflike, green or reddish brown, shorter than inflorescences. Spikes: proximal pistillate spikes 1-3(-4) (basal spikes 0, rarely 1); cauline spikes overlapping or somewhat separated, with (2-)5-15 perigynia; staminate spikes 8-30 × 1.3-4.1 mm. Scales: pistillate scales pale brown to dark reddish brown or purplish brown, narrow white margins, elliptic to ovate, 2.6-5.4 × 1.2-2.6 mm, equaling perigynia, apex acute to acuminate or short-awned (rarely obtuse); staminate scales with white margins 0.4-0.8 mm wide, lanceolate to obovate, 3.6-6.7 × 1.2-1.7 mm apex obtuse to long-acuminate. Anthers (1.5-)2-3.8 mm. Perigynia yellowish green to pale brown or olive, veinless, obovoid, 2.8-4.6 × 1.5-2.2 mm, as long as wide; beak straight, pale green, occasionally with reddish tinge, 0.4-1.3 mm, weakly ciliate-serrulate, apical teeth 0.1-0.7 mm. Stigmas 3. Achenes dark brown, obovoid to globose, obtusely trigonous in cross section, (1.4-)1.6-2.5 × 1.5-2.2 mm.