of animals, serving the purpose of seed dispersal. This causes damage to domesticated livestock and degrades wool. Range and habitat T. terrestris is now widespread throughout the world from latitudes 35°S to 47°N. It is distributed across warm temperate and tropical regions of southern Europe, southern Asia, throughout Africa, New Zealand, and Australia. It is also present across southern North America and in Central and South America. Over the 20th century, it appeared in California and became distributed northward, eventually appearing in British Columbia, Canada where it is classified as a noxious weed. A network of fine rootlets arise from the taproot allow the plant to survive in arid conditions. It grows in almost any soil, but thrives in dry, loose, sandy soils, and even in sand or in deserts. It can prosper in heavier soils, especially if fertile or moist, and on compacted soils along roadsides. Etymology The Greek word, τρίβολος meaning 'water-chestnut', translated into Latin as tribulos. The Latin name tribulus originally meant the caltrop (a spiky weapon of similar shape), but in Classical times the word already meant this plant as well. Cultivation The plant is widely naturalized in the Americas and also in Australia south of its native range. In some states in the United States, it is considered a noxious weed and an invasive species. It is a declared plant (infestations described under "caltrop") in South Australia. Uses The leaves and shoots are eaten in East Asia. The stems have been used as a thickener, added to diluted buttermilk to give it the appearance of undiluted buttermilk. There is some evidence that T. terrestris was used in traditional medicine. Dietary supplement Although its extract has been used as a dietary supplement since the 1980s in belief that it increases testosterone levels to aid body building or sexual enhancement in men, T. terrestris did not consistently affect testosterone levels in controlled studies, has not been proven to be safe, and may adversely interact with prescription drugs. High-quality research on T. terrestris extract has not been conducted, and no reviews indicate that it has strength-enhancing properties, or anabolic steroid effects for use as a body-building supplement or sexual enhancement. The Australian Institute of Sport discourages athletes from using T. terrestris supplements. Phytochemistry Phytochemicals of T. terrestris include steroidal saponins. Eradication In areas where it is an invasive species, T. terrestris is often sought to be eradicated. However,