Acmella in Flora of China @ efloras.org

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).

1 Capitula radiate (2)

+ Capitula discoid (4)

2 (1) Leaf blade ovate to deltate, leaf bases broadly obtuse, truncate to slightly cordate; capitula ovoid; mature achenes with obvious corklike margin. 1 A. ciliata

+ Leaf blade lanceolate, elliptic to narrowly ovate, leaf bases attenuate or cuneate; capitula cone-shaped; mature achenes without obvious corklike margin (3)

3 (2) Disk florets 4- or 5-lobed; corollas light yellow or greenish; ray florets relatively inconspicuous; phyllaries 7-11; disk floret achenes 1.5-3 mm. 6 A. brachyglossa

+ Disk florets 4-lobed; corollas yellow to orange; ray florets conspicuous; phyllaries 5 or 6; disk floret achenes 1.2-1.8 mm. 3 A. uliginosa

4 (1) Pappus absent; achenes glabrous. 2 A. calva

+ Pappus of 2 or 3 setae; achenes moderately to densely ciliate (5)

5 (4) Mature achenes with corklike margin. 5 A. paniculata

+ Mature achenes without obvious corklike margin (6)

6 (5) Corollas 4-lobed; phyllaries 1-seriate; capitula 4-6 mm in diam. 3 A. uliginosa

+ Corollas 5-lobed; phyllaries 2- or 3-seriate; capitula > 10 mm in diam. 4 A. oleracea

Lower Taxa