Any of several unrelated shrubs or small trees of desert regions in the southwest United States and Mexico, having tiny, early deciduous leaves and branches and stems resembling a mass of thorns.刺马甲子:任一种产于美国西南部和墨西哥境内沙漠地带的无关联灌木或小树木,生有细小的早期脱落的叶片和一团棘刺状的树枝和树干