Description from Flora of China
Rhizome with rather thick stolons. Culms 30-60 cm tall, stiff, triquetrous, smooth, clothed with dark red or red-brown bladeless sheaths at base, remnant sheaths usually disintegrating into reticulate fibers. Leaves shorter than culm, blades 3-4 mm wide, flat, stiff, with distinct transverse septate nodes between veins, sheathed. Involucral bracts leafy, lower ones longer than inflorescence, upper ones nearly not sheathed, lowermost involucral bract shortly sheathed. Spikes 5-7; terminal 2-4 spikes male, distance between spikes short, linear-cylindric, 2-5 cm, nearly sessile; remaining spikes female, remote, cylindric, 2.5-5 × 0.8-1 cm, densely many flowered, upper ones shortly pedunculate, lower one long pedunculate. Female glumes pale, lanceolate, ca. 5 mm, membranous, 3-veined, apex acuminate, shortly aristate. Utricles stramineous, usually dark red flecked, obliquely patent, longer than glume, oblong-ovate, inflated trigonous, 5-6.5 mm, leathery, glabrous, several veined, base rounded, apex gradually narrowed to a slightly broad and medium-sized beak, orifice 2-toothed. Nutlets slightly loosely enveloped, obovate or ovate, trigonous, ca. 3 mm, base stipitate; style slightly thick, stiff; stigmas 3. Fl. and fr. Apr-Jun.
● Damp places at riversides or ditch sides. Anhui, Hubei, Jiangsu.