August Weed of the Month: Puncturevine

Home Weed-of-the-Month, WeedsAugust Weed of the Month: Puncturevine

August 6, 2025• Weed-of-the-Month, Weeds• Samuel Leininger

Puncturevine (Tribulus terrestris) is a plant that lives up to its name. This invasive weed has spiny seed heads that can easily puncture bike tires, inflatable rafts, animal paws, and footwear. Unfortunately, this invasive noxious weed has been increasing in our area.

Also known as “goatheads”, puncturevine is native to southern Europe. This Oregon state-listed Class B noxious weed thrives in hot, dry, rocky conditions where other plants can not. It is most commonly found along roadsides, sidewalks, and parking lots. Puncturevine is opportunistic and is also showing up in orchards, pastures, and ditch banks.

Puncturevine is a summer annual broad leaf weed that grows low to the ground, forming dense mats typically one to five feet in diameter. Stems from the plant radiate out from the center and can spread up to six feet. Flowers are small, yellow, and have five petals. The leaves are hairy and compounds with opposite leaflets.

The most notable aspect of puncturevine is its dangerous and numerous seeds! These seeds have long spikes that painfully attach to passing animals, tires, shoes, or people.

Puncturevine seeds germinate in the summer and produce a shallow taproot. Once established, plants can begin flowering within three weeks. Puncturevine seeds can remain viable in the soil for up to five years and a typical plant will produce 200 to 5,000 seeds during one growing season.

Why Should I Care About Puncturevine?

Puncturevine poses a serious problem for agriculture and recreation here in Clackamas County. The plant quickly spreads for a central taproot. It can form dense patches that compete for water and nutrients needed by trees, crops, and native plants. The sharp spikes of the seed can cause physical injury to people and animals. Additionally, puncturevine vegetation can be toxic to sheep and cattle, causing nitrate poisoning, blindness, and death in young animals.

For outdoor recreationists, puncturevine can turn a lovely day into a disaster by harming a person, or a beloved pet, or puncturing equipment. Even the toughened paws of a well-exercised pet is no match for these thorny seeds. The spiny thorns of the puncturevine seeds are notorious for flattening bike tires, and inflatable watercraft leaving recreationists stranded.

How Can I Control Puncturevine?

While puncturevine is certainly a painful invader, there is good news. Puncturevine is easily removed by hand once detected. Just be sure to pull the entire taproot and then bag all parts of the plant and place it in the garbage for landfill disposal. Be sure to gather up any seeds that may have dropped to the ground during removal. Do not dump pulled weeds or the infestation will just begin anew in another area.

Once the seed is established, monitor and remove plants as they emerge and continue to do so for several years. Shallow tilling of seedlings or small plants can be effective in larger areas. Two weevils have been used successfully as biological controls, but are not sufficient by themselves to manage puncturevine.

Keep puncturevine from spreading by thoroughly checking and cleaning clothes, pets, equipment, and vehicles.

For more information on chemical control of this invasive plant, please review the additional resources below or contact us today!

Report Puncturevine!

Have you noticed invasive puncturevine in your area? If so, please contact the WeedWise program to report your sightings, or submit your information online to the Oregon Invasive Species hotline. Your help in identifying and reporting locations of puncturevine in our community will help to stop the next invasion before it starts.