Description from Flora of China
Scirpus quinquangularis Vahl, Enum. Pl. 2: 279. 1805; Fimbristylis fauriei Ohwi; F. quinquangularis var. bistaminifera Tang & F. T. Wang; F. quinquangularis var. elata Tang & F. T. Wang.
Annuals or short-lived perennials. Rhizomes absent or very short. Culms tufted, 14-120 cm tall, 5-angled, bearing 0-3 bladeless sheaths. Basal leaf sheaths 3-17 cm, cylindric, mouth oblique. Leaves on vegetative shoots with only blades, shorter than to subequaling culm; leaf blade 2-3 mm wide, flat. Involucral bracts 4, setaceous, much shorter than inflorescence, margin finely serrulate. Inflorescence a decompound anthela, 5-9 × 3-6 cm; rays 4, 1-4 cm, scabrid. Spikelets solitary, ovoid, 2-5 × 1.2-1.5 mm, apex acute to subobtuse. Glumes chestnut-brown, ovate, ca. 2 mm, 3-veined forming an abaxial keel, lateral 2 veins dark brown, margin paler, apex obtuse and apiculate. Stamens 1 or 2; anthers oblong, ca. 0.5 mm, ca. 1/3 as long as filament. Style 3-sided, basally slightly inflated, apically slightly pubescent; stigmas 3, slightly longer than style. Nutlet obovoid, 0.8 mm or longer, 3-sided, verruculose and with transverse linear reticulation. Fl. and fr. Aug-Oct. 2n = 10.
Swamps; 800-2100 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hunan, Jiangxi, Sichuan, Taiwan, SE Xizang, Yunnan, Zhejiang [Afghanistan, India, Indonesia, Kazakhstan, Nepal, Pakistan, Papua New Guinea, Philippines, Sri Lanka, Thailand, Uzbekistan, Vietnam; Africa, SW Asia, Australia, Indian Ocean islands, Madagascar].