This shrub is most easily recognized by its gray-white, smooth stems and rigid, forked branchlets with thorn-like twigs. The tiny flowers are white, blue or lavender, in 3–15 cm long clusters. Leaves are oval, 10–25 cm, alternate and 3-veined, greenish above and glaucous below. Leaf margins are entire, or with tiny glandular teeth. Leaf stipules are thin and scale-like.