Description from Flora of China
Herbs, perennial. Leaves alternate, sessile or shortly petiolate, entire or serrate, or rarely pinnately lobulate, pinnately veined. Synflorescence terminal, compound with dense clusters of capitula densely aggregated in secondary heads surrounded by leaflike bracts, secondary heads solitary or variously arranged into panicles or spikes. Involucre cylindric, slightly compressed; phyllaries generally 8, in 4 decussate pairs, oblong, apex acute or apiculate, outer 4 shorter than inner 4. Receptacle small, naked. Florets 4; corolla purplish or white, tubular, with funnelform limb; lobes 5, usually more deeply cleft between 2 inner lobes. Anthers shortly acute, shortly hastate at base, obtusely auriculate. Style branches filiform, apically subulate. Achenes oblong-obovoid, somewhat flattened, 10-ribbed, setose, often glandular between ribs. Pappus sparse, bristles 5 to many, scabrid-barbellate, basally widened, rarely reduced to a scaly corona. x = 11.
About 30 species: pantropical, mostly in South America; two species in China.