Bristly greenbrier is a stout, perennial woody vine with bristlelike black spines, climbing high by tendrils to a length of 40 feet.
Leaves are alternate, simple, 2–6 inches long, 2–5½ inches wide, oval, egg-shaped, heart-shaped, to broadly lance-shaped; tip blunt to pointed; margin entire but sometimes minutely toothed; upper surface green, smooth, shiny, with the 5–7 main veins sunken; lower surface paler, smooth. Leaf stalk gradually expands into the blade, often twisted and bent. Leaves persist into winter. This greenbrier species is among the most variable in leaf size and shape.
Stems are green with minute white dots, finely grooved, with few or no prickles on the outer branches; young prickles yellow, older prickles black throughout, round, bristlelike; tendrils arise in pairs at the base of leaf stalks. Bark is green to brown, hard, densely covered with prickles and hairs; prickles on bark nearly black, up to ¼ inch long.
Flowering is in May–June. Flowers yellowish green, small, with male and female flower clusters on the same plant, in clusters of 5–26 flowers; cluster stalks ½–1¼ inches long, much longer than the leaf stalks; petals 6.
Fruits mature September–October. Fruit a bluish-black berry, usually lacking a whitish coating, about ¼ inch thick, globe-shaped; cluster stalks flattened and much longer than the leaf stalks. Seeds usually 1 (sometimes 2) per fruit.