39. Cyperus nutans Vahl, Enum. Pl. 2: 363. 1805.
垂穗莎草 chui sui suo cao
Perennials. Rhizomes short, hardened. Culms scattered, 75-110 cm tall, stout, compressed 3-angled, smooth, with leaves at basal part. Leaves shorter than culm; leaf blade 6-12 mm wide, flat, margin scabrous. Involucral bracts 4-8, leaflike, basal 3 or 4 usually longer than inflorescence, to 1.2 cm wide, abaxially serrulate apically on 2 lateral veins, margin scabrous. Inflorescence a compound anthela; rays 8-10, to 16 cm, each with 4-10 raylets. Spikes cylindric, 2-5 cm × 4-7 mm, with laxly arranged spikelets. Spikelets linear to narrowly linear-ovoid, 5-11 × ca. 1.5 mm, suberect, 6-10-flowered; rachilla flexuose, wings white and hyaline. Glumes yellowish on both surfaces and rusty brown striate, lax, elliptic, ca. 2 mm, spreading after anthesis, membranous, 7-9-veined, keel reddish brown, apex mucronate. Stamens 3; anthers linear-oblong; connective prominent beyond anthers. Style very short; stigmas 3, slender, exserted. Nutlet dark brown when mature, oblong to obovoid-oblong, ca. 2/3 as long as subtending glume, 3-sided, densely and slightly prominently punctate. Fl. and fr. May-Oct. 2n = 56.
Sparse forests, grasslands on mountain slopes, water margins in valleys, wet places, river margins, fields; below 100-1600 m. Guangdong, Guangxi, Guizhou, Hainan, Hunan, Sichuan, Taiwan, Yunnan [Bhutan, India, Indonesia, Laos, Malaysia, Nepal, Papua New Guinea, Sri Lanka, Thailand, Vietnam; Africa, Australia].