Saguaro cacti, Carnegiea gigantea, only grow in the Sonoran Desert. However, they are limited by elevation, generally found between sea level and 4,000'. In Saguaro National Park, studies indicate that a saguaro grows between 1 and 1.5 inches in the first eight years of its life. branches normally begin to appear when a saguaro reaches 50 to 70 years of age. When a saguaro reaches 35 years of ageit begins to produce flowers. Thoughnormally found at the terminal end of the main trunk and arms, flowers mayalso occur down the sides of the plant. Flowers will continue to be produced throughout a saguaros lifetime. An adult saguaro is generally considered to be about 125 years of age. It may weigh 6 tons or more and be as tall as 50 feet. This tremendousweight is supported by a circular skeleton of inter-connected, woody ribs. The number of ribs inside the plant correspond to the number of pleats on the outside of the plant. In late April through early June, the tops of the saguaros trunk and armssprout numerous large, creamy white flowers. Individual flowers open at night and close the following afternoon.To develop into fruits, they must be pollinated within this time frame. Pollination is carried out by nectar feeding bats, birds and insects. The average life span of a saguaro is thought to be 150 - 175 years of age.
A mature Saguaro cactus in the Superstition Wilderness - Phoenix, Arizona.