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DescriptionAnnual herbs (in ours) or subshrubs. Leaves opposite, entire. Capitula solitary, terminal, heterogamous, radiate; ray florets female, disk florets bisexual; all florets fertile. Phyllaries in 3 (or more) series, overlapping, the outer shorter. Receptacular scales folded longitudinally, enclosing the disk florets. Achenes of ray florets triquetrous, of disk florets flattened, striate. Pappus of 1-3 awns or teeth, sometimes 0 in ray florets.