Tribulus terrestris

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, and Australia, and is an invasive species. Like many weedy species, this plant has numerous common names according to the world region, including goat's-head, bindii, bullhead, burra gokharu, bhakhdi, caltrop, small caltrops, cat's-head, devil's eyelashes, devil's-thorn, devil's-weed, puncture vine, and tackweed. Tribulus terrestris is a taprooted herbaceous plant that grows as a summer annual in temperate climates. Native to the Mediterranean region, T. terrestris is 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 present across the United States and in Central and South America. Over the 20th century, the vine appeared in California and became distributed northward, eventually appearing in the Okanagan Valley of south-central British Columbia, Canada where it is classified as a noxious weed. A network of fine rootlets arise from the taproot to take advantage of soil moisture, by which the plant can 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. The stems radiate from the crown to a diameter of about 10 cm (3.9 in) to over 1 m (3 ft 3 in), often branching. They are usually prostrate, forming flat patches, though they may grow more upwards in shade or among taller plants. Stems branch from the crown and are densely hairy. Leaves are opposite and pinnately compound. Densely hairy leaflets are opposite and up to 3 mm (0.12 in) long. The flowers are 4–10 mm (0.16–0.39 in) wide, with five lemon-yellow petals, five sepals, and ten stamens. In Southern California, it blooms from April through October, where it is highly invasive in waste places and disturbed sites.