The saguaro is a large, tree sized cactus native to the Sonoran Desert. The saguaro blossom is the State Wildflower of Arizona.
Saguaros have a relatively long life span. It takes 50 to 75 years to develop their first arm. The arms themselves are grown to increase the plant's reproductive capacity.The growth rate of saguaros is strongly dependent on precipatation; saguaros in drier wester Arizona like Organ Pipe Cactus National Monument grow only half as fast as those in and around Tucson. In the Catalina and Rincon Mountains, it may be 50 years for their first arm. In Organ Pipe or Cabeza Prieta NWR along the Mexico border it may be 75 years. In Saguaro National Park East it is not at all unusual to see Saguaros with 20-25 arms. Some specimens may live for more than 150 years and can can grow anywhere from 15 to 50 feet. They grow slowly from seed, and not at all from cuttings. Whenever it rains, saguaros soak up the rainwater. The cactus will visibly expand, holding in the rainwater. It conserves the water and slowly consumes it.
Saguaros can not self pollenate. Large quantities of pollen are required for complete pollination as there are numerous ovules. A well-pollinated fruit will contain several thousand tiny seeds. The ruby red fruit ripen in June. Each fruit contains around 2000 seeds plus sweet fleshy connective tissue. The fruits are highly edible and prized by local people. The O'odham tribes have a long and rich history of saguaro fruit use. Native birds such as Gila Woodpeckers, Gilded Flickers, Purple Martins, and House Finches live inside holes in saguaros bored by the woodpeckers. Flickers excavate larger holes higher on the stem. The nest cavity is deep, the parents and young entirely hidden from view. The saguaro creates callus tissue on the wound. When the saguaro dies, and soft flesh rots the callus remains behind, a so called "saguaro booty" which was used by natives for storage.
The major pollinators are bats, primarily the Lesser Long Nosed Bat, feeding on the nectar from the night-blooming flowers, which often remain open in the morning. Doves and bees appear to be the primary daytime pollinators.
|View from Saguaro National Park looking north toward the Catalina Mountains|
A few of the dead Saguaros, which provide wonderful skeletons: