Annuals, perennials, or subshrubs [shrubs], 20-400 cm. Stems erect or ascending [decumbent], sparingly to freely branched. Leaves cauline; opposite (proximal) or alternate [whorled]; petiolate (petioles often ± winged, often with expanded bases, those bases sometimes fused to form nodal 'discs') [sessile]; blades 3-nerved from bases, mostly deltate to ovate [linear], sometimes 3- [5-]lobed[pinnatifid], bases cordate to cuneate, ultimate margins entire or toothed, faces hirsute, hispid, pilose, puberulent, scabrous, or scabro-hispid [sericeous], often gland-dotted or ± stipitate-glandular to glandular-puberulent. Heads radiate [discoid], borne singly or in 2s or 3s, or in tight to loose, corymbiform [paniculiform] arrays. Involucres campanulate [ovoid-campanulate to urceolate], 5-16[-22] mm diam. Phyllaries persistent, [11-]13-43[-66] in 2-4 series (tightly appressed to broadly reflexed, unequal to subequal). Receptacles low-convex, paleate (paleae conduplicate, ± enclosing cypselae). Ray florets [0-]5-21[-45], styliferous and sterile; corollas orange-yellow [lemon-yellow, pink, purple, or white]. Disc florets [12-]13-154[-172], bisexual, fertile; corollas concolorous with rays (usually turning purple apically), tubes (often glandular-hairy) shorter than throats, lobes 5, ± triangular (anthers black, yellow, or yellow proximally and bronze or purple distally; style branches relatively slender, apices sometimes attenuate). Cypselae flattened, thin-margined [thickened, biconvex] (shoulders minute to conspicuous, faces glabrous or hairy); pappi 0, or fragile or readily falling, of 2 ± subulate scales [plus 4-12 shorter scales]. x = 17.