Annual or rarely perennial erect herbs, with fibrous roots. Leaves alternate, oblong or obovate, uppermost sometimes simple and entire, lower mostly 2-3-pinnatisect or 1-2-pinnatifid, with apex 2-3-partite, the margin lobed or dentate towards the semi-amplexicaule base. Capitula radiate, heterogamous, solitary, terminal or 2-5 per branch in lax corymbs, with peduncles often thickened toward apices. Involucre 2-3(-4)-seriate, phyllaries many-nerved, imbricate. Receptacle convex, without scales or paleae. Ray-florets pistillate, with yellow or sometimes white, apically 2-3-fid ligules, fertile. Disc-florets hermaphrodite, tubular, the corolla tube laterally expanded, 5-lobed, lobes with central resin sacs. Cypselas dimorphic and sometimes compressed, thick-walled, those of the ray-florets triquetrous or winged, disc cypselas mostly laterally flattened, narrowly winged adaxially, or cylindrical, 10-ribbed or angular, all epappose.