Description from Flora of China
Perennials. Culms 2-4 m tall, 6-7 mm wide, 3-angled, glabrous. Leaves ± in whorls of 3; sheaths ca. 4 cm, papery, glabrous, basal ones winged; contraligule nearly semicircular, very short, margin ciliate; leaf blade linear, ca. 40 × 1-1.3 cm, thickly papery, slightly scabrous, apically attenuate. Involucral bracts leaflike, basalmost to 25 cm, sheathing; bractlets setaceous, laterally hairy, base dilated. Inflorescences compound paniculate, with several branches; lateral branches often 2 or 3 in a cluster, 6-7 × ca. 10 cm, spreading, axes angled. Spikelets 1 or 2 in a cluster, brown, ca. 5 mm, unisexual, basal glumes distichous. Male spikelets oblong-ovoid, apex truncate; glumes rust-colored to brown, 2-3.5 mm, membranous, basal ones keeled and with a cuspidate apex. Female spikelets narrowly ovoid, apex acuminate; glumes broadly ovate-lanceolate, ovate, or oblong-ovate, keeled. Male flowers: stamens 3; anthers linear, ca. 1.2 mm; connective apex protruding, ca. 1/4 as long as anther. Female flowers: stigmas 3. Disk brown, purple, yellowish, or bright shiny red, cup-shaped, 1/2-4/5 height of nutlet and enclosing it, 3-lobed; lobes smooth, shiny, apex dentate. Nutlet flattened globose, ca. 1.5 × 2-2.5 mm, with hexagonal reticulation, sparsely pubescent, apex cuspidate. Fl. and fr. Apr.
Stream margins; 200-300 m or less. Hainan, Taiwan (Pingdong) [Cambodia, India, Indonesia, Laos, Malaysia, Myanmar, Philippines, Sri Lanka, Thailand, Vietnam; N Australia, Indian Ocean islands, Pacific islands].