White vine (Sarcostemma clausum) is found only in the southern third of the Florida peninsula and in Texas. It is a vining member of the milkweed family and tends to occur in moist hammock edges and near the edge of open wetlands. It is evergreen, but subject to freeze damage if temperature reach below 32 degrees F, and may bloom at most months of the year if not interrupted by extreme cold.
White vine is an aggressive rambler and will ultimately grow many feet in every direction. Its succulent elliptical leaves are opposite each other on the stout stems and exude a milky sap, like most milkweeds, if injured. This foliage serves well as food for milkweed butterfly caterpillars and I have seen monarchs, queens and soldiers feeding on them at various times.
The flowers are typical of the family, though the petals do not curve backwards to the extent most milkweeds in the genus Asclepias do. They are produced in large clusters along the stems and are white in color. Pollinated flowers produce the typical ear-shaped follicle that eventually splits open - sending the fuzzy-winged seeds airborne to new locations.