4. Eleocharis acutangula (Roxburgh) Schultes, Mant. 2: 91. 1824.
锐棱荸荠 rui leng bi qi
Scirpus acutangulus Roxburgh, Fl. Ind. 1: 216. 1820; Eleocharis fistulosa Schultes; S. fistulosus Poiret (1805), not Forsskål (1775).
Perennials. Stolons slender. Culms erect, pale green, tufted, 30-75 cm tall, (1-)3-4 mm thick, sharply 3-angled, smooth, glabrous, without transverse septa. Leaf sheaths 2 or 3; basalmost sheath brown, glumelike; cauline sheaths tubular, 5-15 cm, base dark red to dark purple, mouth obliquely truncate, apex acute. Spikelet pale green, cylindric, 1.5-4 cm × 3-5 mm, many flowered, apex acuminate. Basalmost glume empty, broadly ovate, amplexicaul for whole spikelet base; fertile glumes laxly imbricate, broadly ovate, ca. 4.5 × 3.5 mm, purplish red puncticulate, medially grayish yellow, subleathery, and with several veins including a conspicuous midvein, margin membranous, apex rounded. Perianth bristles 6, longest ca. 1.5 × as long as nutlet, retrorsely spinulose. Stigmas 3. Nutlet pale yellow, broadly obovoid to obovoid, ca. 2 × 1.5 mm, biconvex, shallowly pitted with 13-15 longitudinal rows of transversely oriented oblong to linear epidermal cells, apex slightly constricted and with a conspicuous annular thickening; persistent style base subdeltoid, not spongy, base ca. 3/5 as wide as nutlet. Fl. and fr. Jun-Sep.
Flooded fields, moist areas; 500-1800 m. Fujian, Guangxi, Hainan, Hong Kong, Taiwan [Cambodia, India, Indonesia, Japan, Laos, Malaysia, Myanmar, Nepal, Papua New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; tropical Africa, America, and Australia, Madagascar].