Goathead - Tribulus terrestris
Hillsboro, NM, USA
August 2015
When I was a boy growing up near Dexter, New Mexico in the southeastern part of the state, I knew about Goatheads. After all, I had a bicycle and goatheads were the reason that I spent so much time patching the inner tubes of the tires; that I spent so many hours carefully pouring milk through the stem valve into the inner tube so that it could curdle and “self-heal” some of the wounds created by the dreaded beasts; and most of all, goatheads were one of the many dangers awaiting dirty young feet - even when they had been hardened by months of avoiding shoes. Yes, I know about goatheads. However, I admit that at that young age there were many things I did not know about them.
Goatheads (Tribulus terrestris) are also called Puncture Vine and many other appropriate names - like “Devil’s Weed”. There are a number of scientific synonyms for this species.
Tribulus terrestris has a fruit with many sharp points, a schizocarp, which can puncture bike tires, feet, and many other things of value (photo above). It is an annual which reproduces well, biological controls, typically weevils, are used to limit the reproduction of the species. Each schizocarp encloses several seeds. The weevils bore into the schizocarp (before it splits apart) and eats the seeds.
One thing I did not appreciate in my youth is that how many of my brethren were sharing my agonies. Tribulus terrestris, is an exotic plant, being introduced from many other places in the world. Its range is widespread in the United States and Canada, dark blue indicates that it is present in the state, light blue indicates that it is present in the county, and pink indicates that it is (officially) considered noxious.
Linnaeus first described the species in 1753. A specimen collected in Kansas is shown below.
