Annual herbs. Leaves alternate,
divided. Capitula radiate, heterogamous. Phyllaries
1-2-seriate; ± membranous. Receptacular scales
flat. Ray florets female; disk bisexual. Rays yellow or
orange-yellow. Achenes oblong-cylindric, with a thick pale
margin. Pappus 0 or reduced to a minute disk. Worldwide: 13 species in N and Central America, especially Mexico; the Galapagos and one pantropical weed (C. americanum) Zimbabwe: 1 taxon. |