33. Cyperus rotundus Linnaeus, Sp. Pl. 1: 45. 1753.
香附子 xiang fu zi
Cyperus rotundus var. quimoyensis L. K. Dai.
Perennials. Stolons slender, with ellipsoidal tubers. Culms solitary, rarely 2 laxly tufted, 15-90 cm tall, slightly slender, triquetrous, smooth, base swollen into a tuber, leaved at basal part. Leaves equaling or shorter than culm; sheath brown, usually disintegrating into fibers; leaf blade bluish green, 2-5 mm wide, ± flat. Involucral bracts 2 or 3(-5), longer to sometimes shorter than inflorescence. Inflorescence a simple or compound anthela; rays (2 or)3-10, mostly to 12 cm, unequal in length, spreading. Spikes obdeltoid, with 3-10 slightly laxly arranged spikelets. Spikelets obliquely spreading, linear, 1-3 cm × 1.5-2 mm, 8-28-flowered; rachilla wings white, slightly broad, hyaline. Glumes blood-red to purplish brown on both surfaces but middle green, subdensely imbricate, ovate to oblong-ovate, ca. 3 mm, 5-7-veined (fading some distance before margin), apex acute to obtuse and muticous. Stamens 3; anthers linear; connective prominent beyond anthers. Style long; stigmas 3, longer than style, exserted from glume. Nutlet obovoid-oblong, 1/3-2/5 as long as subtending glume, 3-sided, puncticulate. Fl. and fr. May-Nov. 2n = 80, 84, 96, 100, 104, 108, 110, 112, 116, 124, 132, 138, 160, ca. 200.
Grasslands, wet or dry areas on mountain slopes, stream margins, along trails, sandbanks, ditch margins, water margins in valleys, paddy field margins; near sea level to 2100 m. Anhui, Chongqing, Dongsha Qundao, Fujian, S Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, S Liaoning, Nansha Qundao, S Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xisha Qundao, SE Xizang, Yunnan, Zhejiang [Afghanistan, Bhutan, India, Indonesia, Japan, Kazakhstan, Korea, Kyrgyzstan, Malaysia, Myanmar, Nepal, Pakistan, Papua New Guinea, Philippines, Sri Lanka, Tajikistan, Thailand, Uzbekistan, Vietnam; Africa, SW Asia, Australia, Central, North, and South America, Europe, Indian Ocean islands, Madagascar, Pacific islands].
The tubers are used as a Chinese medicine. The species is generally considered to be one of the world’s worst weeds.