Annual to perennial herbs, sometimes shrubs or trees, rarely epiphytes or climbers. Lvs usually opposite or alternate, sometimes whorled, often all basal, simple and entire to variously dissected, rarely compound; stipules 0. Fls (florets) commonly 5-merous, ☿, neuter or unisexual, sessile, nearly always in compact heads (capitula) on a common receptacle, sometimes individually subtended by bracts (scales), the whole capitulum surrounded by few to many bracts, very rarely florets solitary in panicles or capitula reduced to 1 floret. Capitula solitary or few to numerous in dense or diffuse cymes, panicles or less often spikes, racemes or other infl. types. Calyx epigynous, modified as pappus of scales, awns or hairs, sometimes reduced to a small corona or 0. Corolla epigynous, actinomorphic and filiform or tubular, or zygomorphic with an extended limb (ligule), often the outer florets ligulate (ray florets) and the inner tubular (disc florets) or all florets either ligulate or tubular. Stamens as many as corolla lobes and alternate with them; filaments free; anthers 2-locular, usually connate into a tube, very rarely scarcely connate, dehiscing introrsely. Ovary inferior, 1-locular; style 2-fid, often undivided in ♂ florets; ovules solitary, anatropous. Fr. usually an achene, often crowned by a persistent pappus, rarely a drupe.