Bidens bipinnata L., Sp. Pl. 832. 1753; Kitamura, Acta Phytotax. Geobot. 9: 29. 1940; Mem. Coll. Sci. Kyoto Imp. Univ., Ser. B, Biol. 16: 275. 1942; Li, Fl. Taiwan 4: 803. 1978.
Stems 25-85 cm tall, erect, tetragonous, slightly puberulous on upper part, branched. Median cauline leaves opposite, 11-19 cm long, more of less pubescent on both surfaces (petioles 3.5-5 cm long, wingless), bipinnatipartite, lower segments often 2- or 3-cleft or pinnatifid, terminal segments narrow, acuminate, few-dentate; upper leaves gradually smaller, uppermost alternate, small, pinnati-partite. Heads 6-10 mm broad; peduncles 1.8-8.5 cm long. Involucre cupuliform, bracts 5-7, lanceolate, 2.5 mm long to 5 mm long in fruit, linear-oblong, apex obtuse or acute, outer palea oblong, 3.5-4 mm long, to 6-8 mm long in fruit, obtuse, inner ones narrowly obtuse, 5 mm long to 12 mm long in fruit. Ray florets 1-3, yellow, 5-6 mm long. Disc florets fertile, corolla yellow, tubular, 4.5 mm long, 5-lobed. Achenes long linear, 10-12×1 mm, 3- or 4-angular, more or less short strigose. Pappus awns 3 or 4, 3-4 mm long. Chromosome number, 2n = 72 (Peng & Hsu, 1978).
HSINCHU: Chupei, Lienhuassu, Peng 8589. PINGTUNG: Kenting Natl. Park, Sheting, Peng 12511; Kenting Park, Peng 12574.
Probably native of eastern United States and eastern Asia, naturalized in South America, Australia, South Asia and Europe. Taiwan, usually in the south, along roadside and in waste grounds.