Description from Flora of China
Scirpus bisumbellatus Forsskål, Fl. Aegypt.-Arab. 15. 1775.
Annuals. Culms densely tufted, 4-20 cm tall, slender, flatly 3-angled, smooth, with few leaves at base. Leaves shorter than culm; sheath yellowish green with rust-colored flecks, short, white pilose; leaf blade 0.7-1.5 mm wide, flat, margin apically ciliate, abaxially sometimes sparsely hairy. Involucral bracts 2-5, leaflike, suberect, basal 1 or 2 equaling or longer than inflorescence. Inflorescence a compound or decompound anthela, lax; rays 4-10, to 4 cm, slender. Spikelets solitary, oblong-ovoid, ovoid, or oblong, 2-7 × 1-1.8 mm, 10-20-flowered, apex acute. Glumes spirally imbricate, brown, broadly ovate, 1.2-2 mm, membranous, 3-veined forming an abaxial green keel. Stamens 1 or 2; anthers narrowly oblong-ovoid. Style long and compressed, ciliate, basally inflated; stigmas 2. Nutlet yellowish white, very shortly stipitate, broadly obovoid, ca. 0.8 mm, biconvex, with transversely oblong reticulation. Fl. and fr. Jul-Sep(-Nov). 2n = 10, 16, 20.
Along rivers, streams, sandy or marshy places, wet places on slopes; 100-1500 m. Anhui, Guangdong, Guangxi, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xinjiang, Yunnan, Zhejiang [Afghanistan, India, Indonesia, Japan, Laos, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, Turkmenistan, Vietnam; Africa, SW Asia, Australia, Europe, Indian Ocean islands].