Crossosomataceae (rockflower) is a small family of only six species (in four genera - apacheria, crossosoma, glossopetalon and velascoa), five of which occur in southwestern USA. Plants are trees or shrubs, with thorny branches and simple, alternate, untoothed leaves, lacking stipules. Flowers are radially symmetric, with four or five sepals, four or five petals, up to 50 stamens and up to nine carpels.