Several varieties of wild grapes grow in these parts. Their viny, big-leaf foliage can all look similar, but their fruit can range in color from deep, dark purple, to blueberry blue, to maroon red.
Stith: "Is Austin overrun with wild grapes? Has it always been ... heart-shaped to deeply lobed, green leaves, to five inches, concave, wooly below, with coarsely tooth edges.