Also known as Puncture Vine, Devil’s Thorn and other unflattering names. Likely you know the plant as Goatsheads, since it’s thorns, or nutlets, resemble a goat’s head. Native to the Mediterranean but now naturalized to many countries around the world, like numerous other noxious exotics (example: Yellow Star Thistle), it was introduced here in North America (thanks a lot whoever you were!). Goatsheads are the very bane of mountain bikers, as a quick search on the net shows. The spikes on the thorns are diabolically sharp and so are also quite painful for bare feet.
Another name for Tribulus terrestris is Caltrops because of its similarity to the war weapon of the same name, a spiked metal thing meant to impede vehicles.
Here’s a typical plant:
Star shaped clusters break into five nutlets:
Goatsheads are tough, prolific and seem to prefer dirt areas of high traffic like driveways, the sides of roads, litter filled lots and mountain bike trails (evidently). Still, in all my hikes, as far as I remember at least, I’ve only seen them on a hiking trail once.
I’ve got a collection from other areas though:
I figure there’s at least 10,000 there! A half pound of pain.
One of my flip-flops:
Interestingly, there is anecdotal evidence of medicinal benefits from the plant. However warnings also exist for it’s use.
The thorns probably serve two purposes, 1) as protection against predation and 2) as a means of transport to new locales (via the bottoms of unwilling feet, or buried in scruffy fur). How to get rid of Goatheads? I don’t like poisoning the ground so I rely on manual removal, which is actually quite effective if done thoroughly: whenever I see it I take a hoe to it – before it can put out it’s thorns. Depending on the area, that can begin as early as winter and continue until fall. Using boiling water is reputed to work well too.
This is a planet of great variety and means of survival, not always pleasant to us, but all part of the big evolutionary picture. In frustrating cases like this, perhaps it’s best to take some of it with a bit of humor. 😉