Low maintenance groundcover plants that are willing to grow in poor soil with little irrigation are generally quite welcome in most areas.
And the plant pictured certainly looks pretty damned healthy for something growing in hard pack clay and gravel with no water and zero protection from the blazing hot sun.
Better yet, look at how it is spreading so nicely to cover the ground while maintaining an extremely low growth habit. Looks like it might even be a really pleasant ground cover for paths or walkways.
Closer inspection reveals that it even has these really pleasant little yellow flowers!
Cute, even! And it is covered in them!
How can anyone not love this plant?
But, wait, what is this?
Every one of those little yellow flowers turns into a seed pod. The fruit of the vine, if you will.
And every one of those little seed pods breaks apart into four or five sections, each with quarter inch spikes.
While the spikes are semi-hard when green (hard enough to puncture skin), they turn iron-hard when dry. The design of the little seed pod sections is such that they spikes point up.
How hard are they?
Hard enough to go through bike tires, thin soled shoes, people feet, animal skin, and — even — small car tires.
And they hurt likely bloody hell. Typical to thorns like this, the surface has some kind of irritant on it that causes the puncture wounds to be extremely painful.
Roger and I have been on a personal vendetta to eliminate this evil plant wherever we find it. It is one of the few plants that I might actually consider using chemicals on.
As you can see in the picture, this ground crawling vine can get to be quite large. That isn’t even the largest one we have eliminated in the area.
Recently, I ran into a nasty patch of it on one of the trails in Cupertino that I ride my bike to work on. Obviously, an infestation of puncture vine along a public walkway can be very painful and unpleasant to folks using said path.
I contacted Cupertino Parks and Recreation and they had the plant eradicated within a day! Very impressive!
Update: As the summer wore on, a couple more sprouts popped up here and there. Cupertino Parks & Rec eliminated them in short order. Clearly, they keep an eye on outbreaks! Nice!