Tribulus terrestris is an annual plant in the caltrop family (Zygophyllaceae) widely distributed around the world. It is adapted to grow in dry climate locations in which few other plants can survive. It is native to warm temperate and tropical regions in southern Eurasia, Africa, North America, and Australia. Tribulis Terrestris capsules contain natural steroidal chemicals called saponins, which are the active ingredient in Tribulis Terrestris. This supplement is widely used by body builders for its effects.