Stems: one to three feet high, branches broadly spreading, smooth. Leaves: ovate or oval, opposite, entire, smooth above, usually hairy beneath. Flowers: open-campanulate, five-parted, lobes revolute. Fruit: slender elongated terete seed pods, usually in pairs.

A plant with quantities of little spreading branches bearing oval spine-tipped leaves and numerous pink flowers, veined with a deeper red, in loose terminal and axillary convex clusters. The plant is full of a milky juice.