|Goathead thorn, or "nutlet", from my bike tire|
The thorns of this plant, Tribulus terrestris, known as "puncture vine" and a bunch of other names, are hard on bike tires. I've had several kevlar-based puncture layers on different tires punched right through by them. Only one I can think of it didn't go right through was a Continental Ultra Gatorskin, and I'm thinking Schwalbe Marathon Supremes might also hold up, but these little "nutlets" go through tough stuff--stuff that rejects tacks and glass regularly. Also, the geometry of the spike seems such that it often renders tire sealant ineffective.
At least I was able to wait until I was in my house, in the air conditioning, to pull it out and change the tube. After I pulled this one out of the tire, careful to not puncture my finger at the same time, I found another spike poking inside the tire casing, too, from another goathead, this one of the ground-off, directly in the tread type.
I've mentioned them on the blog before, of course, but didn't think I had a good photo of one. Now I do. There's something in there about "any ride might have its thorns," but I'm tired, and honestly just glad this one was easy to take care of, and that there don't seem to be too many out there. The large patches of the weed are recognized for the menace they are, and dealt with quickly, yet, somehow, the stray nutlet still shows up in my tire somewhat regularly. Seemingly more often when the weather turns blisteringly hot.