August’s Weed of the Month!

Its August, and that means its time for a new Weed of the Month!

We are working with our partners at the Columbia Gorge Cooperative Weed Management Area to promote Puncturevine  (Tribulus terrestris) as our weed-of-the-month for August.

Puncturevine is a sprawling annual plant that forms a dense mat with very sharp, spiny seed heads. This nasty weed is invading from areas outside Clackamas County from the east and from the south.  Also known as goathead, puncturevine has branched stems that can spread up to 6 feet wide, stemming from a single crown. Flowers are small, yellow and have 5 petals. The leaves are hairy, 1-3 inches long, and divided into leaflets, each about 1/4 inch long. The seed head is woody with very sharp spines. Seeds are easily spread by sticking into footwear, vehicle tires and animals. Puncturevine thrives in sunny, dry, rocky locations such as roadsides or gravel parking lots.  This plant poses serious problems for recreationalists and agriculturalists alike.  The seeds can easily puncture a bike tire, inflatable raft or dog’s paw. Puncturevine has been found recently in orchards, roadsides, and parking lots where seeds are being spread by tires and other farming activities.  Plants are actively producing seeds now and will continue to do so until we get frost.

If you see pincturevine, pull it and please report it to the Oregon Invasives Hotline at  This is a high priority weed in our area, so please report all sightings.  If you pull plants, try to get the entire taproot, all of the seeds, bag it and put it in the garbage for landfill disposal.   This is one to nip in the bud!

Puncturevine_Aug Weed Alert_Poster

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WeedWise Program