25. Cyperus digitatus Roxburgh, Fl. Ind. 1: 209. 1820.
长小穗莎草 chang xiao sui suo cao
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.
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].
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.