Sunset with moon and Saguaro Cactus (Carnegiea gigantea) in the Sonoran Desert. Saguaro grow 15 to 50 feet tall. Can live to 150 years; takes 75 years to develop a side arm. Trunk expands like an accordion when holding in rainwater. Grow from seed only (no cuttings). Organ Pipe Cactus National Monument, Est. 4/13/1937, 330,689 acres (133,825 ha). Pima County, AZ.