It’s been a warm spring. Goat head, AKA puncture vine, bull thorn, tack vine, and other descriptive names, is already growing all over the lot and starting to bloom and crawl over the curb on the huge vacant lot on M Street, at Milbank. That means that they are also sprouting in front of the vacant warehouse two doors down at 1080 M, on the vacant lot on the NW corner of M and Parkway. Within a month, they will be puncturing passing bike tires. It is a weed of public, commercial and vacant lots; people usually don’t tolerate it around their residences once they become acquainted with the seeds.
Lot full of goathead, Milbank and M Streets
Goat heads make a 5-sided seed head that falls apart when ripe into five hard, tack-shaped seeds that stick in shoes, dogs’ feet, and tires. They have leaves divided into 5-11 leaflets and five-petaled symmetrical yellow flowers about ¼ inch wide. They usually lie flat to the ground, but can pile up to several inches, and can spread out a yard wide.
Ripening goat heads. Credit: Forrest and Kim Starr
The seeds apparently are broken up by high-speed driving, so car and truck tires do not usually spread them and are apparently too thick be punctured by them. But they are a good reason to have flat-free tires on wheelbarrows, bikes and trailers.
Goat head seeds. Credit: Steve Hurst @ USDA-NRCS PLANTS Database
In the mid-80’s we were able to ride bikes all over town and country without being troubled by goat heads, which I had to go to Arizona to become acquainted with. By the time I came back in 1999, they were already here, and I pulled them on sight. Within 5 years, there were so many that I stopped pulling them on properties I do not control. A few years ago, I started pulling them on public property where I can, and agitating to enforce our nuisance codes against this noxious weed.
Goat head flower. Credit: Forrest and Kim Starr
They apparently do not spread far or fast, except on bike tires and riding mowers. People pull them out of their shoes and dogs’ feet ASAP. At the Wastewater Treatment plant, they apparently came out of the lawn and were brought there by riding mowers from other properties. Since they have not been weeded out, they are being spread to other properties on riding mowers by the City’s contractor. The same has been happening for years at Schroeder Park near their dog park.
They have a deep, strong taproot that can be pulled when the ground is damp by gathering the foliage and pulling the crown where the vines meet, in places like watered lawns, where they thrive.
They also thrive in dry soil, where they are nearly impossible to pull. But they can easily be cut off their roots below the crown with pruning scissors, and they do not grow back.
I did just that for two months last year, around the Wastewater Treatment Plant, in anticipation of the City building a dog park on that property, which they have done. But I expect to be killing them there for the next five years or more; their seeds don’t all sprout at once, and they last a long time.
5/18/2013. Published on Yahoo Voices
Rycke Brown, Natural Gardener 541-955-9040 firstname.lastname@example.org