Description from Flora of China
Low erect annuals. Stems winged, branches spreading. Leaves alternate, obovate to oblong, mucronulate-serrulate to dentate, decurrent, gland-dotted. Capitula disciform, heterogamous, in terminal solitary, globose, or ovoid clusters, with or without bracts between capitula, clusters sessile on a common receptacle. Involucre campanulate, narrow; phyllaries narrow, dry, few seriate, unequal, scarious, acute or obtuse. Receptacles naked, commonly globose or disciform, with few bracts or not. Marginal florets female, few to many, fertile, slender, minutely 2- or 3-dentate. Disk florets bisexual, solitary or few, fertile or sterile, tube thickened, limb 4- or 5-dentate. Base of anthers obtuse to sagittate, auricles acute or tailed; endothecial tissue radial. Style of disk florets terete, style branches filiform or connate, with obtuse sweeping hairs reaching below furcation. Achenes oblong, somewhat flattened, truncate at apex, base contracted. Pappus absent. x = 10.
About 40 species: tropical and subtropical Africa and Asia, also in Australia; three species in China.