Koeberlinia spinosa

Koeberlinia spinosa is a thorny shrub native to the southwestern United States and northern Mexico, known by common names that include crown of thorns, allthorn, smokebush and crucifixion thorn. It is one of two species in the genus Koeberlinia, which is sometimes treated as the only genus in the family Koeberliniaceae and is otherwise placed in the caper family. The plant is moderate to large in size and sprawls to heights above four metres, forming a tangle of straight, repeatedly branching green stems that each end in a long sharp spine. Its leaves are rudimentary, tiny deciduous scales, so most photosynthesis happens in the green stems. It flowers abundantly with white to greenish-white blooms and bears shiny black berries a few millimetres long, which attract birds. It grows on the northern Mexican Plateau, down into the northern foothills of the Sierra Madre Oriental, and west into the Sonoran Desert of Sonora and Arizona and parts of Baja California Sur.