Description from Flora of China
Scirpus nutans Retzius, Observ. Bot. 4: 12. 1786.
Annuals or short-lived perennials. Rhizomes extremely short or absent. Culms densely tufted, 15-85 cm tall, subcylindric, stiff, striate, smooth, glabrous, with leaf sheaths at base. Leaves bladeless; leaf sheath brown, basal ones glumelike and apical ones cylindric, margins membranous, apex obliquely truncate. Involucral bract 1, glumelike, ovate, 2-4.5 mm, apex mucronate. Inflorescences reduced to a single terminal spikelet, ovoid, ellipsoid, or oblong-ovoid, 5-15 × 2-5 mm, slightly nodding, 10- to many flowered. Glumes rather densely spirally imbricate, brown with short rust-colored lines, broadly ovate to subelliptic, 3-5 mm, papery, veins many but abaxially faint, apex rounded and mucronate. Stamens 3; anthers linear. Style long and compressed, basally slightly inflated, apically sparsely ciliate; stigmas 2, short. Nutlet white with a very short brown stipe, obovoid, 1.2-1.5 mm, flatly biconvex to sometimes nearly flat-convex, with transverse wavy reticulation and verruculose margins. Fl. and fr. Jul-Aug.
Wet places. S Fujian, Guangdong, Guangxi, Hainan, S Hunan, Taiwan [India, Indonesia, Japan (Ryukyu Islands), Malaysia, Myanmar, Papua New Guinea, Sri Lanka, Thailand, Vietnam; Australia].