Puncturevine

Tribulus terrestris

puncturevine blooming at Academy Village

About the Plant

This plant is an ARIZONA NOXIOUS WEED!

Puncturevine has been a pest since its introduction into the US in the early 1900s. It competes with farm crops and poisons livestock. The spiny fruit is dangerous to the feet of all animals, including humans, and can injure the mouths and digestive tracks of animals who eat it. The spines on the fruit are hard and sharp enough to puncture the tires of bicycles, lawn mowers, and other small equipment.

In our area, puncturevine begins to grow with the summer monsoon rains. You'll probably notice it as a mat of foliage covering the ground, though the flowers are noticeable, too. It is an annual, so the plant will not regrow if it is dug out of the ground. Make sure to pick up any fruit that fall to the ground. The seeds will germinate in the next 2-5 years, so any area where puncturevine was found should be monitored for several years and any new plants removed.

Wildlife value: none

More Information

Weekly Plant on puncturevine

Arizona Noxious Weed List

Map of distribution in US (light blue indicates plant is present and not native; pink indicates states in which plant is considered noxious)

Technical Botanical Description from SEINet

ID Characteristics

This plant is in the Zygophyllaceae - the caltrop family.
Puncturevine grows from a center point, with stems flat against the ground (in shady spots it may grow more upright). Each stem can be up to 5 feet long and a heavy stand can cover the ground.
The leaves are opposite and pinnately compound, making this plant fairly easy to recognize. Each leaf is from 1-3 inches long with 5-8 pairs of oval leaves. Both the leaves and the stem are visibly hairy. Click on the photo to enlarge so you can see the hairs.
The flowers are axial (emerge along the stem just above a leaf) and held singly. Each flower is 1/4-1/2 inch across with 5 sepals and 5 separate, yellow petals. There are 10 stamen with yellow anthers. The ovary is superior with a 5-lobed stigma.
The fruit has 5 sections that eventually fall apart. Each section has two large spines, that give rise to the common names of goathead or bullhead, and other smaller spines. The arrangement is such that the fallen section almost always lands with one of the large spines pointing upward. The fruit sticks to fur, shoes, and tires, all excellent ways to distribute the seed far and wide. In photo, note that the 5-lobed stigma is visible in the center of the fruit.