Description from Flora of China
Cyperus digitatus var. laxiflorus L. K. Dai; C. digitatus var. pingbienensis L. K. Dai.
Perennials. Rhizomes woody, very short. Culms tufted, 0.5-1.5 m tall, stout, triquetrous, smooth, basally with leaves. Leaves nearly as long as culm; sheath purplish brown, long; leaf blade 4-15 mm wide, flat or folded, subleathery. Involucral bracts 5-7, leaflike, longer than inflorescence. Inflorescence a compound or decompound anthela; rays 6-10, usually to 18 cm, each with 4-7 raylets; raylets unequal in length. Spikes at apical part of raylets, cylindric, 3-6 × 0.4-2 cm, without a peduncle, with many laxly arranged spikelets. Spikelets subdistichous, linear to narrowly ovoid, 3-12 × 1-1.5 mm, slightly compressed to compressed, spreading to obliquely spreading, 4-40-flowered; rachilla winged, wings lanceolate and laterally detaching from rachilla with nutlet maturation, with successive glumes 0.9-1.2 mm apart. Glumes straw-colored, reddish brown, or golden-yellow on both surfaces, densely imbricate, ovate to elliptic, 3-5-veined, keel greenish, apex mucronate. Stamens 3; anthers yellow, linear, ca. 0.5 mm; connective not prominent beyond anther apex. Style long; stigmas 3, shorter than style. Nutlet dark gray at maturity, oblong-ellipsoid, 1/2-3/5 as long as subtending glume, 3-sided, puncticulate. Fl. Jul-Oct, fr. Aug-Dec. 2n = 84, 104, 108.
If subspecies are recognized, plants in Asia would belong to Cyperus digitatus subsp. digitatus. Cyperus digitatus subsp. auricomus (Sieber ex Sprenger) Kükenthal occurs in Africa.
Open areas in forests, ditches, wet places; near sea level to 1800 m. Guangxi, Hainan, Hong Kong, Taiwan, SE Xizang, Yunnan [Bangladesh, India, Indonesia, Laos, Malaysia, Myanmar, Nepal, Pakistan, Papua New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; Africa, tropical America and Australia, North America, Pacific islands].