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.[2] It can thrive even in desert climates and poor soil. Like many weedy species, this plant has many common names, including puncturevine, caltrop, cathead, yellow vine, goathead, burra gokharu and bindii.[1][3]
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"Goathead" fruit
Thumbtack-like Tribulus terrestris nutlets are a hazard to bicycle tires.
It 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 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.

this guy even got some puncture-vine weevils which ate all the goatheads.

http://www.goatheads.com/home/gh1/pa...cturevine.html