Xanthium L.
Burrs solitary or few together in the axils of alternate leaves, each burr containing 2 fruits Xanthium
Stems without spines
Leaves usually 3–5-lobed, ovate, 5–15 cm long, cordate at the base, petiole and veins purplish. Burrs ellipsoid, 16–18 mm long, with 2 larger terminal straight spines. Herb up to 2 m high with purplish stems. Widespread. Weed of cultivation and waste places, particularly along creek flats. Fl. summer–autumn. Noogoora Burr or Cockle Burr Xanthium occidentale
Leaves very shallowly and unevenly lobed, ovate, up to 12 cm long. Burrs ellipsoid, 15–30 mm long, with 2 larger terminal straight spines 6–8 mm long. Herb up to 1 m high. Weed of cultivation and waste places, particularly along creek flats. Fl. summer–autumn. South American Burr Xanthium cavanillesii