|Leaves and flower|
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 Australia. It can thrive even in desert climates and poor soil. Like many weedy species, this plant has many common names, including bindii, bullhead, burra gokharu, caltrop, cat's head, devil's eyelashes, devil's thorn, devil's weed, goathead, puncturevine, and tackweed.
Tribulus terrestris is a taprooted 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 6 mm (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 to three 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.
The Greek word, τρίβολος meaning 'water-chestnut', translated into Latin as tribulos. The Latin name tribulus originally meant the caltrop (a spiky weapon), but in Classical times already the word meant this plant as well.
Cultivation and uses 
Dietary supplement 
Some body builders use T. terrestris as post cycle therapy or "PCT". After they have completed an anabolic-steroid cycle, they use it under the assumption that it will restore the body's natural testosterone levels.
The extract is claimed to increase the body's natural testosterone levels and thereby improve male sexual performance and help build muscle. Its purported muscle-building potential was popularized by American IFBB bodybuilding champion Jeffrey Petermann in the early 1970s. However, T. terrestris has failed to increase testosterone levels in controlled studies. It has also failed to demonstrate strength-enhancing properties, a finding indicating that the anabolic steroid effects of Tribulus terrestris may be untrue. Some users report an upset stomach, which can usually be counteracted by taking it with food.
Traditional medicine 
In traditional Chinese medicine Tribulus terrestris is known under the name bai ji li (白蒺藜). According to Bensky and Clavey, 2004 (Materia medica 3rd edition, pp. 975–976) Tribulus terrestris is ci ji li (刺蒺藜). "Confusion with Astragali complanati Semen (sha yuan zi) originally known as white ji li (白蒺藜 bai ji li), led some writers to attribute tonifying properties to this herb..."
T. terrestris has long been a constituent in tonics in Indian Ayurveda practice, where it is known by its Sanskrit name, "gokshura/ sarrata" It is also used in Unani, another medical system of India.
Research in animals 
T. terrestris has been shown to enhance sexual behavior in an animal model. It appears to do so by stimulating androgen receptors in the brain.T. terrestris is now being promoted as a booster for the purpose of increasing sex drive. Its use for this purpose originated from a Bulgarian study conducted in the 1970s, which found effects on free testosterone and luteinizing hormone in men belonging to infertile couples. A research review conducted in 2000 stated that the lack of data outside of this study prevents generalizing to healthy individuals 
Animal studies in rats, rabbits and primates have demonstrated that administration of Tribulus terrestris extract can produce statistically significant increases in levels of testosterone, dihydrotestosterone and dehydroepiandrosterone, and produces effects suggestive of aphrodisiac activity. On the other hand, one recent study found that T. terrestris caused no increase in testosterone or LH in young men, and another found that a commercial supplement containing androstenedione and herbal extracts, including T. terrestris, was no more effective at raising testosterone levels than androstenedione alone.
The active chemical in T. terrestris is likely to be protodioscin (PTN). In a study with mice, T. terrestris was shown to enhance mounting activity and erection better than testosterone cypionate; however, testosterone cypionate is a synthetic ester of testosterone engineered for its longer activity, rather than an immediate effect. Testosterone cypionate has a half-life of 8 days and is administered every 2–4 weeks in humans for testosterone replacement. The proerectile aphrodisiac properties were concluded to likely be due to the release of nitric oxide from the nerve endings innervating the corpus cavernosum penis. Also, T. terrestris was shown to have strong inhibitory activity on COX-2.
Where this is a non-indigenous species, eradication methods are often sought. There are both biological and herbicidal solutions to the problem, but none of them provide a solution that is both quick and long-lasting, because T. terrestris seeds remain viable for from 3 to 7 years on average.
In smaller areas, T. terrestris is best controlled with manual removal, using a hoe to cut the plant off at its taproot. While this is effective, removing the entire plant by gripping the taproot, stem or trunk and pulling upward to remove the taproot is far more effective. This requires monitoring the area and removing the weed throughout the preseeding time (late spring and early summer in many temperate areas). This will greatly reduce the prevalence of the weed the following year. Mowing is not an effective method of eradication, because the plant grows flat against the ground.
Another avenue of physical eradication is to crowd out the opportunistic weed by providing good competition from favorable plants. Aerating compacted sites and planting competitive desirable plants, including broad-leaved grasses such as St. Augustine, can reduce the impact of T. terrestris by reducing resources available to the weed.
Chemical control is generally recommended for home control of T. terrestris. There are few pre-emergent herbicides that are effective. Products containing oryzalin, benefin, or trifluralin will provide partial control of germinating seeds. These must be applied prior to germination (late winter to midspring).
After plants have emerged from the soil (postemergent), products containing 2,4-dichlorophenoxyacetic acid ("2,4-D"), glyphosate, and dicamba are effective on T. terrestris. Like most postemergents, they are more effectively maintained when caught small and young. Dicamba and 2,4-D will cause harm to most broad-leaved plants, so the user should take care to avoid over-application. They can be applied to lawns without injuring the desired grass. Glyphosate will kill or injure most plants, so it should only be used as a spot treatment or on solid stands of the weed.
A product from DuPont called Pastora is highly effective, but expensive and not for lawn use.
Two weevils, Microlarinus lareynii and M. lypriformis, native to India, France, and Italy, were introduced into the United States as biocontrol agents in 1961. Both species of weevils are available for purchase from biological suppliers, but purchase and release is not often recommended because weevils collected from other areas may not survive at the purchaser's location.
Microlarinus lareynii is a seed weevil that deposits its eggs in the young burr or flower bud. The larvae feed on and destroy the seeds before they pupate, emerge, disperse, and start the cycle over again. Its life cycle time is 19 to 24 days. Microlarinus lypriformis is a stem weevil that has a similar life cycle, excepting the location of the eggs, which includes the undersides of stems, branches, and the root crown. The larvae tunnel in the pith where they feed and pupate. Adults of both species overwinter in plant debris. Although the stem weevil is slightly more effective than the seed weevil when each is used alone, the weevils are most effective if used together and the T. terrestris plant is moisture-stressed.
Two alkaloids that seem to cause limb paresis (staggers) in sheep that eat Tribulus terrestulis are the beta-carboline alkaloids harman (harmane) and norharman (norharmane). The alkaloid content of dried foliage is about 44 mg/kg.
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- Rogerson S, Riches CJ, Jennings C, Weatherby RP, Meir RA, Marshall-Gradisnik SM. (2007). "The Effect of Five Weeks of Tribulus terrestris Supplementation on Muscle Strength and Body Composition During Preseason Training in Elite Rugby League Players". The Journal of Strength & Conditioning Research 21 (2): 348–53. doi:10.1519/R-18395.1. PMID 17530942.
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- Gauthaman K, Ganesan AP, Prasad RN (2003). "Sexual effects of puncturevine (Tribulus terrestris) extract (protodioscin): an evaluation using a rat model". Journal of Alternative and Complementary Medicine 9 (2): 257–65. doi:10.1089/10755530360623374. PMID 12804079.
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|Wikimedia Commons has media related to: Tribulus terrestris|
- Germplasm Resources Information Network: Tribulus terrestris
- Flora Europaea: native distribution in Europe
- Page on T. terrestris at the Global Compendium of Weeds
- Page from the U.S. Department of Agriculture's PLANTS database
- Tribulus terrestris List of Chemicals (Dr. Duke's Databases)
- Tribulus terrestris in West African plants - A Photo Guide.