Annual or perennial herbs. Lvs alternate or radical, entire, serrate or pinnately lobed; stipules 0. Fls in a capitulum on a common receptacle surrounded by 1-2 series of bracts, 4-6-merous, actinomorphic, usually ☿, rarely unisexual. Calyx tubular, adnate to ovary, angled and dentate. Corolla lobes valvate, terminating a corolla tube. Stamens as many as and alternating with corolla lobes, inserted towards top of tube; filaments ± connate; anthers 2-locular, dehiscing longitudinally, ± connate around style. Ovary 1-locular, inferior; style undivided; ovule solitary, pendulous. Fr. an achene, the achenes sometimes connate; seed solitary.