Annual, erect, dichotomously branched, pubescent or villous herb; leaves opposite, shortly petioled, ovate lanceolate, margins toothed or serrate, scaberulous, 3-nerved; heads small, sessile, heterogamous, radiate, axillary or terminal; receptacle small, flat; involucre ovoid-oblong, bracts few, 1-2 outer large, foliaceous, inner linear-lanceolate, shining; ray florets 1-2 seriate, fertile, ligulate, short, 2-3 toothed, yellow; disk floret bisexual, fertile, tubular, limb 4-lobed, yellow; stamens 5, epipetalous, syngenecious, anthers sagitate, anther bases subentire; ovary 1-celled, 1-ovuled, solitary, basal, obtuse, style arms long with acute tips; achenes of ray dorsally compressed, 2-winged, smooth, wings lacerate; achenes of disk narrower, compressed or triquertrous often muricate, the angles of both terminating in spines; spines 2-3 times as long as erect, very stout; pappus awned.