Mediterranean annual or biennial herb having pinkish to purple flowers surrounded by spine-tipped scales; naturalized in America
They are scattered on the ground where an enemy's cavalry are to pass, to impede their progress by endangering the horses' feet
An instrument with four iron points, so disposed that, any three of them being on the ground, the other projects upward
A genus of herbaceous plants (Tribulus) of the order Zygophylleæ, having a hard several- celled fruit, armed with stout spines, and resembling the military instrument of the same name
{i} any of several species of plants with spiny heads or fruit; iron ball with four spikes arranged so that one is always pointing upward (used to hinder passage of cavalries or vehicles)