Plants annual herbs, (10-)30-120+ cm tall. Leaf blades ovate to elliptic, 3-18+ cm long, 1-5(9+) cm wide, 1(-2) pinnately lobed, the ultimate lobes lanceolate to linear, 3-50 mm long and 2-15 mm wide, blade surfaces slightly to strongly scabridulous and gland-dotted, occasionally with erect hairs 1-2 mm long. Capitula borne in open panicles on peduncles 1-8(-15) mm long, obscurely radiate; outer phyllaries 5(-6), lance-elliptic, 2-4 mm long; inner phyllaries 5(-6) ovate to orbiculate, 2-5-4 mm long; ray florets 5(-6), pistillate, the lamina orbiculate to oblong, 0.3-1 mm long; disk florets 12-30(-60). Achenes obovoid, 1.5-2(-3.5) mm long, with pappus-like triangular to ovate outgrowths 0.5-1 mm long at the top. 2n = 34.
Parthenium hysterophorus is native to Mexico and the southeastern United States. It is now a widespread weed in tropical, subtropical and warm temperate regions. It is allelopathic, taints milk and meat, and sometimes causes serious contact dermatitis.
Although not included in the Flora of Somalia, Parthenium hysterophorus is a serious, widespread weed in Somaliland, growing in cultivated and urbanized areas. Its distribution in Somalia is not known but is probably similar.
Modified from the account in Flora of North America.
Judging by the absence of records from Somaliland and other areas where this Parthenium hysterophorus is regarded as a noxious, invasive weed, this map only hints at the species' global distribution in tropical and warm temperate regions.