Perennial herbs. Leaves alternate. Flowers bisexual, in terminal heads; involucral bracts absent. Calyx tube cylindric, at length splitting transversely above the ovary, 4 lobed. Stamens 8, rarely more, 2 seriate. Disc linear to lanceolate, unilateral, rarely 2 fid. Ovary subsessile, unilocular; style short; stigma capitate. Fruit dry, enclosed by the persistent calyx base.