Cnidoscolus urens is a perennial, tropical American stinging herb belonging to the family Euphorbiaceae, and is one of some 100 species belonging to the genus Cnidoscolus (Gk. knidē-nettle, skōlos-thorn, Latin urens-burning). The plant is locally known as 'bull nettle', 'spurge nettle' and 'mala mujer' (evil woman).