210. Acmella Persoon, Syn. Pl. 2: 472. 1807.
金钮扣属 jin niu kou shu
Spilanthes sect. Acmella (Richard) Candolle.
Herbs, annual or perennial. Leaves opposite and/or basally rosulate. Capitula solitary or in few-headed cymes, radiate, disciform, or discoid. Involucres ± hemispheric to ovoid; phyllaries 1-3-seriate, subequal or with outer row spreading and longer, entire or irregularly dentate; receptacles conical; paleae falling with achene, ± navicular, membranous to scarious, each ± equaling subtended floret. Ray florets, when present, 2- or 3-lobed, variously colored. Disk florets: corolla yellow or orange, 4- or 5-lobed. Achene margin ciliate, glabrous, or sometimes corky; ray achenes broadly ovate or elliptic, 3-angled; disk achenes ellipsoid, strongly compressed; pappus absent or of up to 10 awnlike bristles. x = 13.
About 30 species: pantropical; six species (four introduced) in China.
See the monograph of Acmella by Jansen (Syst. Bot. Monogr. 8: 1-115. 1985).
The introduction of this genus in Taiwan was detailed by S. W. Chung et al. (Taiwania 52: 276-279. 2007) and K. F. Chung et al. (Bot. Stud. 49: 73-82. 2008).