Description from Flora of China
Scirpus retroflexus Poiret, Encycl. 6(2): 753. 1804; Eleocharis chaetaria Roemer & Schultes.
Annuals. Roots fibrous. Rhizomes and stolons absent. Culms often recurved, tufted, 2-16 cm tall or rarely more, filiform, soft, 5- or nearly 4-angled. Leaf sheaths 1 or 2, pale red, tubular, 2-12 mm; basalmost sheath bladeless; cauline sheaths usually with a glumelike blade at apex. Spikelet purplish red, ovoid, ca. 4 × 2 mm, slightly compressed, few flowered, sometimes proliferous. Basalmost glume empty, subelliptic, amplexicaul for whole spikelet base; fertile glumes green, broadly ovate, 2.8-3 × 1.8-2 mm, herbaceous, with a median keel, edge membranous, margin hyaline, apex acute to obtuse. Perianth bristles 6, nearly as long as nutlet, one on outer series shorter than nutlet, retrorsely spinulose. Stigmas 3. Nutlet yellowish, broadly obovoid, ca. 1.5 × 1 mm, 3-sided, angles prominently costate, reticulate to deeply pitted-reticulate with isodiametric epidermal cells, apex broadly truncate and not constricted; persistent style base pyramidal-acuminate, base as wide as to slightly narrower than nutlet. Fl. and fr. Jul-Nov.
Moist areas in fields. Fujian, Guangdong, Hainan, Yunnan [Cambodia, India, Indonesia, Japan (Ryukyu Islands), Malaysia, Myanmar, Nepal, Papua New Guinea, Philippines, Sri Lanka, N Thailand, Vietnam; Africa, tropical America, NE Australia, Pacific islands].