Annual herbs. Leaves opposite,
simple, strongly 3-nerved from the base; bases sometimes
connate. Capitula numerous, sessile, aggregated in dense
sessile glomerules or cymes, heterogamous; ray florets 1 to
few, with inconspicuous, yellow ligule. Phyllaries 2-3-seriate,
usually with smaller outer bracts. Achenes narrowly obovoid,
somewhat flattened, black, 8-10-ribbed. Pappus 0. Worldwide: 21 species in America and Australia; 2 species are pantropical weeds Mozambique: 1 taxon. |
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