Jamaican Feverplant (aka Puncture Vine), native to Hawaii but introduced in the Southeast, has been added to the USWildflowers database (01/29/2019.) Scientific name is Tribulus cistoides. Photo below was taken at Coquina Beach on Anna Maria Island, Manatee County, FL on Dec 15, 2015. Go to the Jamaican Feverplant detail page for more information and photos.
Jamaican Feverplant – Tribulus cistoides
the variety that grows in SeaBranch State Park is not a vine. It grows into a circular mound. It looks identical, but the growth pattern is different. I will watch and see if it grows spines.
Yeah, I think technically it is not a vine (although the USDA Plants Database lists it as such), but usually has prostrate stems, giving it a vine-like appearance. It apparently can have somewhat erect stems, which would allow it to clump up. It’s also possible you’re seeing Tribulus terrestris rather than T. cistoides. Thanks!
Ok I’ve watched this plant (abundant in SeaBranch State Park) for almost a year, visiting at least once weekly and it never developed spines.