H. Beentje (2005) Xanthium. Flora of Somalia 3:55-552.
Plants coarse herbs, often spiny; monoecious. Leaves alternate. Inflorescences of axilllary unisexual capitula, these solitary or few-together, sessile, subsessile, or shortly pedunculate; male capitula of several flowers; female capitula with 2 flowers surrounded by spiny, woody involucres; female involucres formed by the fusion of the extended receptacle and phyllaries and terminating in 2 long-beaked spines. Male flowers cylindric, 5-lobed; anthers black. Female flowers without a corolla; styles 2-fid. Achenes black; pappuses absent.
Xanthium is a genus of 6 species and 1 naturally occurring hybrid. The genus is native to Central and/or South America. Two species, Xanthium strumarium and Xanthium spinosum, are now serious weeds on all continents but Antarctica. Both are present in Somaliland and are very probably also present in Somalia. Xanthium spinosum tends to be associated with wetter habitats. They differ as shown below:
Xanthium spinosum: Leaf nodes with 1-3-lobed spines 15-30 mm long; leaf blades more or less lanceolate to linera lanceolate or ovate.
Xanthiumstrumarium: Leaf nodes without spines; leaf blades suborbicular, to pentagonal or triangular.
GBIF records include introduced and cultivated plants. Consequently, the distribution shown often differs from statements about a taxon's native distribution.
