16. Fimbristylis littoralis Gaudichaud, Voy. Uranie. 10: 413. 1829.
水虱草 shui shi cao
Annuals or short-lived perennials. Rhizomes absent. Culms tufted, (1.5-)10-60 cm tall, flatly 4-angled, striate, bearing 1-3 bladeless sheaths at base. Basal leaf sheaths (1.5-)3.5-9 cm, sometimes setaceous, compressed bilaterally, attenuate apically, mouth obliquely split. Leaves shorter to longer than culm; sheath bilaterally compressed, abaxially with a membranous and rust-colored margin, adaxially keeled, mouth obliquely split; ligule absent; leaf blade ensiform, (1-)1.5-2 mm wide, bilaterally compressed, margin sparsely and finely serrulate, apically attenuate into a setaceous tip. Involucral bracts 2-4, setaceous, base dilated, margin rust-colored and membranous. Inflorescence a compound, decompound, or rarely simple anthela, subdense, with many spikelets; rays 3-6, 0.8-5 cm, slender, scabrid. Spikelets solitary, globose to subglobose, 1.5-5 × 1.5-3 mm, apex rounded. Glumes chestnut-brown or dark brown, ovate, 1-1.3 or 3.5-6 mm, membranous, 3-veined forming an abaxial keel, midvein green, lateral veins brown, apex obtuse. Stamens 2; anthers oblong, ca. 0.7 mm, ca. 1/2 as long as filaments, apex obtuse. Style 3-sided, not ciliate, basally slightly inflated; stigmas 3, ca. 1/2 as long as style. Nutlet straw-yellow, obovoid to broadly obovoid, ca. 1 mm, obtusely 3-sided, verruculose with transversely oblong reticulation. Fl. and fr. May-Oct.
Field margins, open slopes, muddy places near water, grasslands, paddy fields, paddy field margins; 100-2000 m. Anhui, Chongqing, Fujian, S Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, SE Qinghai, S Shaanxi, Shandong, Sichuan, Taiwan, Yunnan, Zhejiang [Afghanistan, Bhutan, India, Indonesia, Japan, Korea, Malaysia, Nepal, Pakistan, Papua New Guinea, Philippines, Sri Lanka, Vietnam; Africa, SW Asia, Australia, Central, North, and South America, Indian Ocean islands, Madagascar, Pacific islands].