Description from Flora of China
Rhizome long, ligneous. Culms densely tufted, usually 1 or 2 borne in a leaf axil, 3-15 cm tall, subfiliform, rather soft, compressed triquetrous, smooth. Leaves equaling or longer than culm, flat, 1-5.5 mm wide, soft, glabrous, with dark brown persistent leaf sheaths. Involucral bracts sheathlike, blade setiform. Spikes 1-5, androgynous, remote, ovate or ovate-oblong, 2-5 mm, ca. 3.5 mm thick, densely many flowered; male part of spike shorter than or nearly equaling female part, slightly thin. Female glumes white or pale green, ovate, 1.2-1.5 mm, papery, 1-costate and laterally few veined, margins narrowly membranous, apex rounded or obtuse. Utricles pale green, longer than glume, ovate-elliptic, compressed trigonous, 2-2.5 mm, papery, loosely pubescent and ciliate, distinctly 2-veined laterally and thinly few veined, base cuneate, nearly estipitate, apex attenuate into an indistinct short beak, orifice obliquely truncate. Nutlets dark brown at maturity, ovate-oblong, trigonous, sides slightly concave, 1-1.5 mm, base cuneate, nearly estipitate, apex with a slightly recurved beak; style rather inflated, slightly compressed, densely brown granular-punctate; stigmas 3. Fl. and fr. May-Sep.
● On wet rocks in forests, wet grasslands at riversides; 500-800 m. Hainan (Ding’an).