2. Cyperus alternifolius Linnaeus, Syst. Nat., ed. 12. 2: 82; Mant. Pl. 28. 1767.
野生风车草 ye sheng feng che cao
Perennials. Roots ± thick, fibrous. Rhizomes short, thick. Culms 0.5-1.5(-3) m tall, slightly stout, obtusely 3-angled to subterete, base with bladeless sheaths, apically scabrid. Basal leaf sheaths yellowish brown; apical leaf sheaths pale green and mostly to 20 cm. Involucral bracts 11-18, leaflike, ca. 2 × as long as inflorescence, subequal in length, 1-14 mm wide, ± horizontal, stiff, margin scabrous. Inflorescence a decompound anthela; rays 8-18, 3-10 cm, each with 1-4 raylets; raylets 1-1.5 cm, each with 3-9 spikelets. Spikelets clustered at apex of raylets, linear to narrowly linear-ovoid, 5-20 × 1-1.5 mm, flattened, 10-40-flowered; rachilla straight, wingless. Glumes pale green, densely imbricate, ovate, ca. 2 mm, membranous, 3-veined, apex acuminate. Stamens 3; anthers linear, ca. 1 mm, apex setose. Style ca. 1 mm; stigmas 3, ca. 1 mm. Nutlet brown at maturity, stipitate, ellipsoid to ovoid, ca. 0.8 mm, 1/3-1/2 as long as subtending glume, compressed 3-sided, apex apiculate. 2n = 32.
Naturalized in wetlands along rivers; below 100-300 m. Taiwan [native to Madagascar].
Cyperus alternifolius is naturalized in many tropical areas worldwide.