Acanthospermum
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Authority
Acevedo-Rodríguez, Pedro & collaborators. 1996. Flora of St. John, U.S. Virgin Islands. Mem. New York Bot. Gard. 78: 1-581.
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Family
Asteraceae
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Scientific Name
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Description
Genus Description - Annual herbs, prostrate to erect; stems appearing dichotomously branched, pubescent. Leaves simple, opposite; blades chartaceous, commonly pinnately 3-veined from near base, the margins subentire to pinnatifid. Inflorescence of solitary, sessile or short-pedunculate heads in the axils and forks of the stem. Heads radiate, several- to many-flowered; involucre hemispheric, of 2 dissimilar series of bracts, the outer involucral bracts green and foliaceous, equal in length and not overlapping, the inner ones light brown, equal in number to ray flowers and tightiy enveloping ray achenes; receptacle slightly convex, paleate. Ray flowers in a single series, pistillate; corollas showy or inconspicuous, pale yellow, with a limb poorly or well developed. Disk flowers functionally male; corollas pale yellow; anthers black. Achenes inseparably enveloped in their involucral bracts forming an involucral false-fruit; fruit weakly or strongly laterally compressed, bearing straight or uncinate prickles; pappus lacking.
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Distribution
A primarily tropical American genus of 6 species, with 1 species (below) introduced to many ports of entry throughout the world.
Saint John Virgin Islands of the United States South America|