Mediterranean annual or biennial herb having pinkish to purple flowers surrounded by spine-tipped scales; naturalized in America Từ đồng nghĩa: star-thistle, Centauria calcitrapa,
tropical annual procumbent poisonous subshrub having fruit that splits into five spiny nutlets; serious pasture weed Từ đồng nghĩa: devil''s weed, Tribulus terestris,