Xanthium

Taxonomic status:Accepted

Occurrence status:Present

Establishment means:Introduced

Annual herbs, often spiny; stems stout, often much-branched. Leaves petiolate, alternate, simple or lobed. Capitula unisexual, sessile, in terminal and axillary clusters, males above, females below. Male capitula subglobose; involucral bracts free, few, 1–3-seriate; receptacle hemispherical, with scales; florets many, tubular; corolla 5-lobed; anthers obtuse at base, with a short apical appendage. Female capitula ovoid; involucral bracts 2-seriate, outer few free, inner 2 connate and completely enclosing florets, hard, apically 2-beaked, covered with hooked spines; florets 2; corolla absent; style with filiform branches protruding through holes below beaks of involucre. Cypselas obovoid or obloid, compressed and one larger than the other (in Victoria), retained inside burr-like involucre which is shed as a unit; pappus absent.

About 30 species (or as few as 3 species if a more conservative taxonomy is followed), widespread in tropical and temperate regions of the world; 8 species naturalised in Australia.

Source: Jeanes, J.A. (1999). Asteraceae. In: Walsh, N.G.; Entwisle, T.J. (eds), Flora of Victoria Vol. 4, Cornaceae to Asteraceae. Inkata Press, Melbourne.
 
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life Life
kingdom Plantae
phylum Tracheophyta
superorder Asteranae
order Asterales
family Asteraceae
Higher taxa
genus Xanthium
Subordinate taxa