59. Cyperus serotinus Rottbøll, Descr. Icon. Rar. Pl. 31. 1773.
水莎草 shui suo cao
Perennials. Rhizomes with long stolons. Culms 35-100 cm tall, stout, compressed triquetrous, smooth, few leaved at basal part. Leaves shorter to sometimes longer than culm; leaf blade 3-10 mm wide, smooth, midvein abaxially forming a keel, base folded, apically flat. Involucral bracts 3(or 4), leaflike, longer than inflorescence, unequal in length, mostly to 8 mm wide. Inflorescence a compound or simple anthela; rays 4-7, obliquely spreading, mostly to 16 cm, each with 1-5 raylets; raylets each with a spike. Spikes with 5-17 spikelets; rachis laxly hispidulous or smooth. Spikelets laxly arranged, subspreading, narrowly ovoid to linear-oblong, 0.8-2.5 cm × ca. 3 mm, 10-34-flowered; rachilla wings white, hyaline. Glumes reddish brown to dark reddish brown on both surfaces, densely imbricate at first but slightly lax after anthesis, broadly ovate, ca. (2-)2.5 mm, papery, 5-7-veined, midvein green, margin yellowish and hyaline, apex obtuse to rounded and sometimes emarginate. Stamens 3; anthers linear. Style short; stigmas 2, long. Nutlet brown, broadly ellipsoid, subglobose, or broadly obovoid, ca. 2 mm, plano-convex, slightly shiny, prominently puncticulate, apex apiculate. Fl. and fr. Jul-Nov.
Swamps, river margins, sandy places by water, shallow water, along trails, shady places, fields; below 100-1300(-2500) m. Anhui, Chongqing, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Ningxia, Shaanxi, Shandong, Shanxi, Taiwan, Xinjiang, Yunnan, Zhejiang [Afghanistan, India, Japan, Kashmir, Kazakhstan, Korea, Kyrgyzstan, Pakistan, Russia, Turkmenistan, Uzbekistan, Vietnam; SW Asia, Europe].