This is a vine that was growing pretty thickly on trees and shrubs in a forest near Greenville, South Carolina. The leaves are cordate with palmate veins. It also had some kind of prickly, pink-brown fruit growing from the stem (often where the leaves branched off)
I am rather certain that this is the introduced plant Dioscorea bulbifera, the air potato. It is spreading fast. More information on this can be found here: http://en.wikipedia.org/wiki/Dioscorea_bulbifera Note the comments on toxicity, please! There are a few other species of Dioscorea in our area, but this looks like this non-native one that I have grown. The ‘fruits’ are actually bulbils, which can be planted to grow new plants – hence its spread. Some consider it a noxious weed.
Dr. Steven R. Hill, Botanist, SCNPS