Aromatic annual or perennial herbs. Leaves cauline, opposite (sometimes alternate above), simple to pinnatisect, glandular. Capitula cylindric, campanulate or fusiform, in terminal cymose panicles; involucral bracts 1-seriate, connate, equal, herbaceous; receptacle flat, naked, pitted. Ray florets few, ligulate, female, variously coloured; disc florets tubular, bisexual; corolla cylindric to campanulate, 5-lobed, variously coloured; anthers truncate or sagittate at base, with an acute ovate apical appendage; style with flattened branches, apex truncate, papillose. Cypselas all similar, linear or clavate, 4-angled or terete, slightly compressed; pappus of 3–10 unequal, basally connate, scarious scales, often 1 or more produced as ciliate awns.
About 50 species, from North and South America; 2 species naturalised in Australia.