Description: Bitter aromatic herbaceous perennial herbs or shrubs.
Leaves alternate, entire to pinnately divided, glabrous to tomentose.
Inflorescence terminal, branched heads numerous; heads broad-campanulate or hemispherical; involucral bracts 2-seriate, outer 5 elliptic to obovate, persistent, inner 5 ± circular, membranous, not persistent, subtending the ray florets; receptacle convex or conical, scales not persistent. Ray florets white, female, fertile, ligules very broad, 2-toothed, persisting on achenes. Disc florets bisexual, sterile, tubular-funnelform. Anthers obtuse at the base, with ovate thickened apical appendages. Style branches glabrous, slightly flattened; styles discoid in sterile florets.
Achenes of ray florets compressed, keeled along inner face, margins thickened and attached to adjacent pair of sterile flowers (shedding as a unit); pappus of 2 or 3 short scales.
Distribution and occurrence: World: 15 species, America & West Indies. Australia: 1 species (naturalized).
Text by L. Murray
Taxon concept:
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