Description from Flora of China
Rhizome slender, ligneous. Culms tufted, 30-55 cm tall, slightly thin, triquetrous, smooth, few yellowish brown and bladeless sheathed at base. Leaves shorter than culm, blades 3-6 mm wide, flat, smooth, sheathed. Involucral bracts leaflike, longer than inflorescences, sheathed, sheath rather long in lowermost part and short in upper part. Spikes 3 or 4, lowermost spike remote, others congregated at top of culm; terminal spike male, linear-cylindric, (1.5-)2-6 cm, nearly sessile; lateral spikes female, oblong-cylindric to cylindric, (1-)2-4 cm, densely many flowered, lower spikes rather long pedunculate, upper shortly pedunculate. Female glumes yellowish brown, with short ferruginous striae, oblong-ovate or ovate, ca. 2 mm, membranous, 3-veined and green on veins, apex acute or obtuse, sometimes mucronate. Utricles yellow-brown, becoming dark purple, obliquely patent, longer than glume, broadly obovate or nearly broadly elliptic, trigonous, 2.2-2.5 mm, membranous, densely purple papillate, 3-5-veined, base gradually attenuate and cuneate, apex abruptly contracted into a very short beak, orifice subtruncate or emarginate. Nutlets yellowish brown, tightly enveloped in utricle, broadly obovate or broadly elliptic, trigonous, ca. 1.5 mm, base abruptly contracted into a short stipe, apex with inflected mucro; style base not thickened; stigmas 3.
Wet places at ditch sides in valleys, forests, grasslands at the foot of mountains; 400-1300 m. Fujian, Guangdong, Hunan, Jiangsu, Jiangxi, Sichuan, Taiwan, Zhejiang [India, Indonesia, Sri Lanka].