1. Tridax procumbens Linnaeus, Sp. Pl. 2: 900. 1753.
羽芒菊 yu mang ju
Herbs, annual to perennial, caulescent, decumbent. Stems procumbent, branched at base, branches slender, spreading or ascending, 20-50 cm, hirsute. Leaves few, shortly petiolate; blade ovate to ovate-lanceolate, 2.5-5 cm, base cuneate, margin deeply irregularly serrate, pinnatisect, segments few, narrow, apex acute or acuminate. Capitula solitary, 1-1.5 cm in diam.; peduncle 10-30 cm; involucre subcampanulate, 6-7 mm; phyllaries few seriate, hispid, outer densely grayish white, elliptic, ca. 5 mm, long hirsute, inner tinged purplish, narrower, ca. 6 mm. Ray florets 4, white. Disk florets yellow, tube ca. 5 mm, limb 5-lobed, lobes reflexed, hairy. Achenes brown, oblong, ca. 2 mm, densely silky pubescent; pappus setae 5-6 mm, shiny, plumose. Fl. Nov-Mar. 2n = 36.
A widespread weed, along exposed dry roadsides, wastelands, lawns. Fujian, Hainan, Taiwan [native to tropical America; now a pantropical weed].