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Annual or perennial herbs or shrubs. Leaves opposite or rarely ternate, the upper leaves often alternate, dotted with resin/oil drops on lower leaf surface. Capitula terminal, solitary or in cymes or panicles, radiate; involucre 2-seriate, the outer leafy, the inner grading into the paleae; paleae 3-veined, the inner keeled. Ray florets female with 3-dentate ray; disc florets cylindric, with pubescent tube, 5-lobed; anthers obtuse or sagittate at base, with apical appendage; style arms short and pilose. Achenes black or brown, obovoid to obconical, the ray-floret achenes 3-angled, the inner 4-angled; pappus absent.
Heads radiate, the rays pistillate and fertile, yellow; invol bracts few, subherbaceous, uniseriate; receptacle convex or conic, its bracts flat or nearly so, membranous or subscarious, striate, subtending rays as well as disk-fls; disk-fls perfect and fertile, the cor densely woolly below the middle; style-branches flattened, with subulate, hairy appendage; achenes glabrous, ± compressed parallel to the invol bracts, often also quadrangular; pappus none; annuals with opposite (or the upper alternate) simple lvs and campanulate or subhemispheric heads. 12, trop. Afr.
