Tribulus terrestris is a flowering plant in the family Zygophyllaceae, native to warm temperate and tropical regions of the Old World in southern Europe, southern Asia, throughout Africa, and in northern Australia. It can thrive even in desert climates and poor soil.
Like many weedy species, this plant has many common names. Puncture Vine, Caltrop, Yellow Vine, Gokshura, and Goathead are the most widely used; others include automobile-weed, bindy eye, bindii, bullhead, burnut, burra gokhroo, calthrops, cat's head, common dubbeltjie, devil's thorn, devil's weed, doublegee, dubbeltje, ground bur-nut, isiHoho, land caltrop, Maltese cross, Mexican sandbur, puncture weed, rose, small caltrops, sticker, tackweed, and Texas sandbur (also T. micrococcus).
It is a tap-rooted herbaceous perennial plant that grows as a summer annual in colder climates. The stems radiate from the crown to a diameter of about 10 cm to over 1 m, often branching. They are usually prostrate, forming flat patches, though they may grow more upwards in shade or among taller plants. The leaves are pinnately compound with leaflets less than a quarter-inch long. The flowers are 4–10 mm wide, with five lemon-yellow petals. A week after each flower blooms, it is followed by a fruit that easily falls apart into four or five single-seeded nutlets. The nutlets or "seeds" are hard and bear two sharp spines, 10 mm long and 4–6 mm broad point-to-point. These nutlets strikingly resemble goats' or bulls' heads; the "horns" are sharp enough to puncture bicycle tires and to cause painful injury to bare feet.
Tribulus terrestris has long been a constituent in tonics in Indian ayurveda practice, where it is known by its Sanskrit name, "gokshura." It’s also used in traditional Chinese medicine for the treatment of various ailments and, most especially, the improvement of men’s sexual functions.
It is now being promoted as a booster for the purpose of increasing sex drive. Its use for this purpose originated in Eastern Europe in the 1970's. Independent studies have suggested that Tribulus terrestris extract slightly increases hormone levels, though leaving them in the normal range.
Some have compared the tonic properties of Tribulus terrestris to the effects of ginseng, but these occur due to entirely different mechanisms. It is also claimed that Tribulus terrestris increases testosterone by increasing gonadotropin-releasing hormone (GnRH) which in turn stimulates the production of LH and follicle-stimulating hormone (FSH). Testosterone, besides its role in muscle-building and raising fertility and libido, is also known to have a positive effect on bone marrow activity (for red blood cell production) and the immune system.