Description from Flora of China
Herbs, annual or perennial; indumentum of simple hairs and sessile globose glands. Leaves alternate, petiole often ill-defined, margin usually dentate, pinnately veined. Synflorescence terminal, paniculate, densely clustered to laxly corymbose. Involucre campanulate or hemispheric; phyllaries imbricate, to 4-seriate, usually with scarious margins, apex obtuse to acute [to acuminate], outer shorter. Receptacle flat or rather convex, naked. Florets [3-]18-24[-50]; corolla purplish or reddish, narrowly tubular, usually with scattered glands, with narrowly campanulate limb, lobes 5, narrow. Anthers obtusely auricled. Style branches subulate, puberulent. Achenes cylindric or obconical, prominently [2-]4- or 5(or 6)-ribbed, glandular between ribs, otherwise glabrous, apex [cupular to] truncate, with well-defined callose ring. Pappus absent.
About 19 species: most in tropical Africa, three or four restricted to Indonesia and Philippines, and one a widely distributed adventive; two species in China.