PLANT: Spiny shrubs or trees.

LEAVES: on new long growth petioled soon deciduous in dry weather, the petioles in part remaining as a spine when the leaf falls; secondary leaves sessile or nearly so, borne in fascicles on short shoots in axils of spines.

INFLORESCENCE: terminal spikes, racemes, or panicles.

FLOWERS: red, yellow, white, or purple; sepals 5 free; petals 5 united into a cylindrical tube; stamens 10-15(-23), adnate to corolla tube; pistil 3-carpelled, the ovary superior, 3-loculed.

FRUITS: 3-valved capsules. x = 12.

NOTES: 1 genus; sw US; Mex.