Description from Flora of China
Scirpus michelianus Linnaeus, Sp. Pl. 1: 52. 1753.
Annuals. Roots many, fibrous. Culms densely tufted, 2-25 cm tall, compressed 3-angled, smooth, few leaved, base not swollen. Leaves shorter to slightly longer than culm; sheath purplish red, short; leaf blade 1-2.5 mm wide, flat or folded. Involucral bracts 3-6, leaflike, much longer than inflorescence, base broad. Inflorescences capitate, pyramidal-ovoid, ovoid, or subglobose, 0.5-1.5 cm in diam., with numerous spikelets. Spikelets densely aggregated at apex of short rays, ovoid to narrowly oblong-ovoid, 3-4 × ca. 1.5 mm, 10-20-flowered or more. Glumes yellowish white but sometimes middle yellowish brown to reddish brown striate, spirally imbricate, oblong-lanceolate, ca. 2 mm, slightly hyaline, 3-5-veined, keel green, apex elongated into a recurved mucro. Stamens (1 or)2; anthers oblong. Style long; stigmas 2(or 3), usually yellow papillate. Nutlet narrowly oblong, ca. 1 mm, 3-sided or plano-convex, margin with white hyaline cells. Fl. and fr. Jun-Sep.
Wet places at water margins or river margins, paddy fields; near sea level to 300 m. Anhui, Fujian, Guangdong, Guangxi, Hebei, Heilongjiang, Henan, E Hubei, Hunan, Jiangsu, Jilin, Liaoning, Shandong, N Xinjiang, SE Xizang, N and NW Yunnan, Zhejiang [India, Japan, Kashmir, Kazakhstan, Korea, Laos, Myanmar, Nepal, Pakistan, Papua New Guinea, Philippines, Russia, Thailand, Vietnam; Africa, SW Asia, Australia, Europe].