Old growth palo Verde tree is covered by a snow on the clffs of the Sierra Anchas in central Arizona. This saguaro grows at 4000 ft. elevation the highest a saguaro can survive. Saguaro is an arborescent (tree-like) cactus species in the monotypic genus Carnegiea, which can grow to be over 20 m (70 ft) tall. It is native to the Sonoran Desert in Arizona.