短舌花金纽扣 duan she hua jin niu kou

Herbs, annual, 10-30 cm tall. Stems usually erect, sometimes decumbent, occasionally rooting at nodes, green or red to dark purple, glabrous to moderately pilose. Petiole 5-37 mm, sparsely to moderately pilose, narrowly winged; leaf blade narrowly ovate to ovate, 1.8-10 × 0.8-6 cm, glabrous to sparsely pilose on both surfaces, base attenuate, margin sinuate to coarsely dentate, apex usually acuminate or acute. Capitula radiate, solitary, ovoid, 6.3-13 × 6.5-9.5 mm; peduncles 4-12.8 cm, sparsely pilose; receptacle 5-11 × 1-2 mm; paleae straw-colored or often with a purple-red tinge in early flowering stage, 3.5-4.6 × 0.5-0.9 mm. Ray florets 5-8; corollas pale yellow, 2-3.1 mm, tube 0.9-1.5 mm, lamina 0.5-1.7 × 0.5-1.5 mm. Disk florets 105-220, pale yellow; corollas 4- or 5-lobed, 1.5-2.1 mm, tube 0.4-0.7 mm, throat 1-1.5 mm, lobes triangular, 0.2-0.4 × 0.2-0.3 mm. Achenes dark brown to black, 1.8-2.3 mm, surface strigose, margin densely ciliate with straight-tipped hairs, without obvious corklike margin; pappus of 2 subequal bristles, longer one 0.5-1.1 mm, shorter one 0.3-1 mm. Fl. Mar-Oct. 2n = 78.

Widely cultivated and naturalized in Taiwan [a weedy species in the Caribbean and Central and South America].