Annual or perennials. Stem erect, usually branched. Leaves simple, opposite and alternate, petiolate or sessile, of various shapes, glabrous or hairy, often gland dotted, dentate or almost entire. Capitula often large, radiate, rarely discoid, solitary, sometimes in corymbs, panicles or spikes. Involucre usually hemispheric, sometimes campanulate or cylindric. Phyllaries 2– or 3– seriate, herbaceous, subequal to unequal, persistent. Receptacle flat to shallowly convex or conical, paleate, paleae conduplicate, mostly rectangular–oblong, usually 3–toothed, rarely entire, apices often reddish or purplish enfolding the cypselas. Ray florets usually 5–30, usually yellow, neuter, rarely absent. Disc florets numerous, bisexual, fertile, yellow or reddish, tube shorter than 5–lobed, campanulate limb, lobes triangular. Cypselas biconvex, obovoid–oblong or 4–angled, usually mottled. Pappus absent or of 2 caducuous, lanceolate, scales–like awns, sometimes with smaller squamellae between them.
A new world (North America, Mexico) genus of about 52 species; introduced in the old world. Represented in Pakistan by two cultivated species.