Desert Discovery Trail Professional Review and Guide
"This self-guided nature trail loops through a small section of desert plains and features small signs that inform you about the plants and animals of the Sonoran Desert. Look for several examples of dead and fallen saguaros, which reveal their inner structure. Unlike trees, saguaros are supported by a ring of woody, individual ribs just under the outer skin of the plant. The interior consists of a moist pulp, which is protected by the ribs. Unlike some desert plants, saguaros do not use deep groundwater to survive dry periods.
Instead, these huge cacti have a shallow root system that collects water rapidly after rains. The entire plant expands as it stores water and gradually contracts as internal moisture is used. Because the shallow root system is incapable of supporting the plant, saguaros are literally balanced on their bases, which some people have found out the hard way after vandalizing a saguaro. In at least one highly publicized case, someone shot at a saguaro with a shotgun from close range. The cactus rocked back and forth a couple of times before falling on the perpetrator and killing him."