Description from Flora of China
Cyperus nutans Vahl subsp. eleusinoides (Kunth) T. Koyama; C. nutans var. eleusinoides (Kunth) Haines.
Perennials. Rhizomes short, surculose. Culms to 1 m tall, stout, 3-angled, smooth, base swollen into a tuber shape, with leaves at basal part. Leaves shorter than culm; sheath long, brown; leaf blade 6-12 mm wide, flat, margin scabrous. Involucral bracts 5 or 6, basal 2 or 3 longer than inflorescence. Inflorescence a compound or decompound anthela; rays 6-12, to 18 cm, each with 3-6 raylets; raylets mostly to 4 cm, unequal in length. Spikes oblong to cylindric, 1-3 cm × 4-10 mm, with very many spikelets. Spikelets densely arranged in several rows, linear-oblong, 4-8 × ca. 2 mm, 6-12-flowered; rachilla wings white, hyaline, caducous. Glumes pale and brown striate or brown, lax, ovate-elliptic, ca. 2 mm, membranous, 5-7-veined, keel green, apical margin white hyaline, apex mucronate. Stamens 3; anthers linear; connective prominent beyond anthers. Style short; stigmas 3, ± long. Nutlet dark brown, obovoid, 3-sided, ca. 2/3 as long as subtending glume, densely and slightly prominently punctate. Fl. and fr. Aug-Dec. 2n = 64.
Forests, mountain slopes, sunny water margins, wet places in valleys; 200-2500 m. Fujian, Guangdong, Guangxi, Taiwan, Yunnan [Cambodia, India, Indonesia, Japan (Ryukyu Islands), Kashmir, Laos, Myanmar, Nepal, Pakistan, Papua New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; tropical Africa, SW Asia, tropical Australia].