Winter grape is a woody vine climbing to a height of 50 feet by means of tendrils.
Leaves are alternate, simple, 4–8 inches long or broad, thin, round to heart-shaped, basal lobes broadly rounded with a narrow sinus (cleft between two lobes) where the leaf stem attaches; margin unlobed or with two short lobes, finely to coarsely toothed; upper surface dark green, with a few cobwebby hairs; lower surface covered with white to gray, cobwebby and straight hairs.
Stems of young branches are angled (not round in cross-section), densely white-felty, green; older branches are grayish brown, striped, with white cobwebby hairs often in patches; tendril emerges opposite the leaf. Bark of old trunks reddish brown, shredding into thin, long, loose strips. Wood porous, lightweight, pale brown.
Flowering is in May–July. Flowers are green, minute; male and female flowers in separate clusters on same plant; petals 5, dropping early. Clusters 4–6 inches long, cylindrical, the cluster stalk with a red tinge, woolly hairy, often with a tendril at the base.
Fruit matures in September–October. Fruit are round black berries, about ¼ inch thick, in long, loose, drooping clusters 3–6 inches long. Berries are tough-skinned and bitter until late autumn. Seeds 1–3 per fruit.