Lophocereus schottii (Senita). Organ pipe cactus. Sunset: 12-13, 16, 17, 21-24; USDA: 9-11. Full sun. Heat tolerant. Little water. Hardy to 18°F. Branching cactus, each stem can grow to 28' tall, 10" diameter. Small white flowers. Origin: AZ, northwest Mexico