Annual or perennial herbs, less frequently shrubs or vines. Stems usually striate. Leaves opposite; blades simple or compound; petioles and rachis narrowly winged or absent. Inflorescences terminal, with one to numerous pedunculate capitula; capitula heterogamous, generally radiate or discoid, with numerous flowers; involucre crateriform, with 2 series of unequal phyllaries, the outer ones green and narrow, the inner ones brown, with hyaline margins. Marginal flowers 5-12, usually sterile, with the corolla ligulate, yellow, white, or orange. Disc flowers few or numerous, bisexual, usually yellow, tubular; stamens 5, the anthers generally black, connate, exserted; ovary inferior, unilocular, the style filiform, with 2 stigmatic branches. Achenes slightly compressed, glabrous or pubescent; pappus composed of 1-6 erect bristles, retrorsely barbate. A genus of about 75 species, mostly of Mexico, also from North America to South America and in the Antilles.
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:225
Specimens with Barcodes:167
Species With Barcodes:32
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