Erect, annual herb; stem and branches grooved, glabrous or somewhat pubescent; leaves opposite, pinnatisect, compound, ultimate segments, linear to filiform, entire, minutely pubescent; heads usually solitary, heterogamous; peduncles slender; involucral bracts 2-seriate,outer bracts linear-lanceolate, inner oblong-lanceolate; ray florets 1-sriate, few, female, ligulate, white, pink or orange; disk florets yellow, bisexual, tubular, 5-lobed; stamens-5, epipetalous, syngenecious, anthers obtuse at base; ovary 1-celled, 1-ovuled, solitary, basal, obtuse, style arms short in ray florets and longer, densely pilose in disk florets; stigma densely hairy below; achenes fusiform or linear, furrowed with retrorsely barbellate awns; pappus absent.