Plants colonial; rhizomes long-creeping. Culms central, slender, trigonous, 40–90 cm, smooth, with marcescent remains of previous year’s leaves at base. Leaves: basal sheaths brownish and tattered on fertile culms, reddish purple on youngest culms, apex glabrous; ligules 1.8–12.5 mm; blades green, M-shaped, often ± septate-nodulose, 2.6–5(–6) mm wide, smooth abaxially, glabrous. Inflorescences 9–35(–45) cm; peduncle of terminal spike (2–)3.5–15 cm; rachis beyond the proximal pistillate spikes sharp-angled, finely scabrous; proximal 1–2 spikes pistillate, not or barely overlapping, ascending; distal spikes erect; terminal 1–3 spikes staminate. Pistillate scales lanceolate to ovate, acute to acuminate, sometimes ± smooth-awned to 1.1 mm, glabrous. Perigynia ascending, 14–22-veined, ovoid, 3.9–7 × 2–3.3 mm, glabrous or densely pubescent; beak 0.5–1.3 mm, bidentulate, teeth straight, 0.1–0.6 mm.