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puncture vine

Tribulus terrestris

Summary 8

Tribulus terrestris is an annual plant in the caltrop family (Zygophyllaceae) widely distributed around the world, that is adapted to grow in dry climate locations in which few other plants can survive.

Description 9

Tribulus terrestris is a taprootedherbaceous plant that grows as a summer annual in temperate climates.

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.

After the flower blooms, a fruit develops that easily falls apart into five burs. The burs are hard and bear two to four sharp spines, 10 mm (0.39 in) long and 4–6 mm (0.16–0.24 in) broad point-to-point. These burs strikingly resemble goats' or bulls' heads, characteristics which give the bur its common names in some regions. The "horns" are sharp enough to puncture bicycle tires and other air-filled tires. They can also cause painful injury to bare feet and can injure the mouths of livestock grazing on the plant.

Within each bur, seeds are stacked on top of each other, separated by a hard membrane. As an adaptation to dry climates, the largest seed germinates first, while the others may wait until more moisture is available before germinating. The bur spines point upward, where they stick into feet and fur of animals, serving the purpose of seed dispersal. This causes damage to domesticated livestock and degrades wool.

Fruit 9

After the flower blooms, a fruit develops that easily falls apart into five burs. The burs are hard and bear two to four sharp spines, 10 mm (0.39 in) long and 4–6 mm (0.16–0.24 in) broad point-to-point. These burs strikingly resemble goats' or bulls' heads, characteristics which give the bur its common names in some regions. The "horns" are sharp enough to puncture bicycle tires and other air-filled tires. They can also cause painful injury to bare feet and can injure the mouths of livestock grazing on the plant.

Within each bur, seeds are stacked on top of each other, separated by a hard membrane. As an adaptation to dry climates, the largest seed germinates first, while the others may wait until more moisture is available before germinating. The bur spines point upward, where they stick into feet and fur of animals, serving the purpose of seed dispersal. This causes damage to domesticated livestock and degrades wool.

Inflorescence 9

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.

Leaves and stem 9

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.

Biological 9

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.

Sources and Credits

  1. (c) Antonio W. Salas, some rights reserved (CC BY), uploaded by Antonio W. Salas
  2. (c) lincolnbc, some rights reserved (CC BY-NC)
  3. (c) Ken-ichi Ueda, some rights reserved (CC BY), uploaded by Ken-ichi Ueda
  4. (c) Ken-ichi Ueda, some rights reserved (CC BY), http://www.flickr.com/photos/ken-ichi/9685888880/
  5. (c) Tony Iwane, some rights reserved (CC BY-NC), uploaded by Tony Iwane
  6. (c) Dan Rademacher, some rights reserved (CC BY), uploaded by Dan Rademacher
  7. (c) Don Loarie, some rights reserved (CC BY), uploaded by Don Loarie
  8. Adapted by Jeny Davis from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Tribulus_terrestris
  9. (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Tribulus_terrestris

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