Puncturevine (Tribulus terrestris) is an attractive green plant with small yellow flowers commonly seen growing prostrate along the side of the road. A native to Southern Europe, it's also referred to as “goathead.” However, underneath its foliage lies danger: spiky seedpods with needle-point spikes. If puncturevine is stepped on, it is painful to bare feet and dogs' paws; it will pierce and flatten bicycle tires. Because of its spiky seedpods puncturevine is also referred to as “caltrop,” after the spiked metal devices thrown on the roadway to stop vehicles. Caltrops have four projecting spikes with one spike always pointed up; just in the right position to puncture a tire or flip-flop, hence the similarity to puncturevine seedpods.
Unfortunately, there are is no easy way to control this noxious weed. For most homeowners, the mechanical control methods of hand removal or cutting the plant off at the taproot are most effective. Any seeds left on the ground must be removed by raking or sweeping. Use heavy gloves to protect hands from the spiky seedpods. Of course, as with any weed, it's best to remove it before it flowers and sets seeds. This is especially important for puncturevine, as seeds are viable for years, and can be spread by shoes or the wheels of lawn mowers or carts.
Biological control using several species of weevils have been tried but are not always effective. Chemical control of puncturevine in the home garden is often unnecessary. However, in heavily infested areas, or when hand removal is difficult, herbicide may be an option.
For more information on puncturevine see the IPM Pestnote No. 74128 on Puncturevine.
- Author: Jeanette Alosi
Puncturevine (Tribulus terrestris) is an attractive green plant with small yellow flowers commonly seen growing prostrate along the side of the road.
Unfortunately, there are is no easy way to control this noxious weed. For most homeowners, the mechanical control methods of hand removal or cutting the plant off at the taproot are most effective. Any seeds left on the ground must be removed by raking or sweeping. Use heavy gloves to protect hands from the spiky seedpods. Of course, as with any weed, it's best to remove it before it flowers and sets seeds. This is especially important for puncturevine, as seeds are viable for years, and can be spread by shoes or the wheels of lawn mowers or carts.
Biological control using several species of weevils have been tried but are not always effective. Chemical control of puncturevine in the home garden is often unnecessary. However, in heavily infested areas, or when hand removal is difficult, herbicide may be an option.
For more information on puncturevine see the IPM Pestnote No. 74128 and the IPM Weed Gallery.
- Author: Guy B. Kyser
Puncturevine (Tribulus terrestris) kept a low profile during the drought years but seems to have exploded following this year's rains. (It is still ‘lying low', so to speak, but there is a lot more of it.)
Also known as goatheads or caltrop, puncturevine is a prostrate annual that produces large, hard, spiked seeds. The seeds disseminate by sticking to animals, tires, and feet, and can easily puncture bike and ATV tires. I tried to do a puncturevine study once but couldn't get the seeds to germinate; my theory now is that the seeds have to be run over by a vehicle before they'll sprout. Conveniently, the plant is commonly found along dirt roads, on roadsides, and on the edges of ag fields.
Puncturevine is native to southern Eurasia and Africa. It is in the plant family Zygophyllaceae, which also includes the creosote bush native to the Mojave Desert.
Extracts from puncturevine seed and other plant parts are available as a dietary supplement, and are reputed to boost virility. I'm guessing this is a holdover from the old medical idea of homology, where the shape of a plant suggested the ailment it was supposed to cure. And the puncturevine seed looks sort of like a goat head, and goats are, you know, lusty. However, WebMD says “Taking tribulus as a supplement for a short time is probably safe, provided that you're healthy and you are not pregnant or breastfeeding.” Hardly a ringing endorsement.
Two species of weevil from puncturevine's native range have been introduced into the U.S. They help keep puncturevine populations in check but they seem to be locked in a boom-and-bust cycle with the plant: when puncturevine populations crash, so do the weevils, and the plant resurges the following year.
More information on this species, including methods for control, are available in a Weed Report at the Weed Research and Information Center and in UC-ANR's Pest Notes.