Puncture Vine (Tribulus terrestris), also known as Caltrop, Yellow Vine, and
Goathead, is an herb used for its virilizing effects.
The plant is native to Eurasia and widely naturalized in the Americas and Australia.
It can thrive even in desert climates and poor soil. In some states in the U.S., it
is considered an invasive species.
Puncture Vine is a taprooted perennial that grows as a summer annual in colder
climates. The stems radiate from the crown to a diameter of about 7.5 to 75 cm (3 to
30 inches), often branching. They are usually prostrate, 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 of clear lemon-yellow, 0.6 cm (a
quarter of an inch) wide, are pretty on the flat little patches formed by the plant.
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, which spread less than 0.6 cm point-to-point. These nutlets strikingly
resemble goats' or bulls' heads; the "horns" are sharp enough to puncture bicycle
tires and to cause considerable pain to unshod feet. |
