Perennial herbs, rhizomatous, fibrous rooted. Stems erect, simple or sparsely branched. Leaves alternate, petiolate or sessile, simple, toothed or entire. Heads heterogamous, radiate, rather small, in spikes or panicles. Involucre campanulate, bracts scarious, imbricate in 3 or 4 series. Receptacle alveolate, flat. Ray florets 1-seriate, pistillate, fertile, corolla ligulate, yellow, very rarely white. Disc florets bisexual, fertile, corolla tubular or narrowly campanulate, 5-lobed. Achenes cylindric, truncate, gradually narrowed to base, glabrous or pubescent. Pappus of many scabrous bristles in 1 or 2 series.
About 150 species in the northern hemisphere, especially in North America; two species in Taiwan, one native and one introduced.
