Olneya tesota (Ironwood)

Native to the Sonoran desert at elevations under 2,500 feet, this slow-growing tree is evergreen except during periods of intense cold or drought. The branches are armed with a pair of spines at the base of each compound gray-green leaf. Pink-purple, pea-like flowers are produced in clusters each spring, followed by hairy brown pods. Plant in full sun and well-drained soils.