Tree of the Week: April 29, 2025

ArborNote spent the last week in Tuscon, Arizona at the Western Chapter ISA Tradeshow and Conference, so our Tree of the Week is the Saguaro Cactus, which is technically not a tree! However, it is such a staple of the landscape in that area that we had to highlight it! It is native to the Sonoran Desert in Arizona, the Mexican state of Sonora, and the Whipple Mountains and Imperial County areas of California. Saguaro typically grow at elevations ranging from sea level to 4,500 feet. They can grow up to 40 feet tall, but they also grow very slowly. For example, Saguaro Cacti only start to grow their “arms” when they reach about 50 years old. Saguaros have a relatively long lifespan, often exceeding 150 years. Arms are developed to increase the plant’s reproductive capacity, as more apices lead to more flowers and fruit. A saguaro can absorb and store considerable amounts of rainwater, visibly expanding in the process, while slowly using the stored water as needed. This characteristic enables the saguaro to survive during periods of drought. It is a keystone species, and provides food and habitat to a large number of species. Saguaros have been a source of food and shelter for humans for thousands of years. Their sweet red fleshed fruits are turned into syrup by native peoples, such as the Tohono Oʼodham and Pima. Their ribs are used as building materials in the wood-poor deserts. The saguaro cactus is a common image in Mexican and Arizonan culture, and American Southwest films.