Saguaro Cactus Question and Answer Guide

Where do saguaros grow?

Saguaro cacti, Carnegiea gigantea, only grow in the Sonoran Desert. However, they do not grow in all parts of the Sonoran Desert. 

 

How do saguaros grow?

Saguaros are a very slow growing cactus. In Saguaro National Park, studies indicate that a saguaro grows between 1 and 1.5 inches in the first eight years of its life. 

 

How does the saguaro reproduce?

In late April through early June, the tops of the saguaro's trunk and arms sprout a profusion of 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. Learn more about how saguaros reproduce.

 

Why are saguaros pleated?

The roots of a saguaro grow out from the plant in a radial fashion, several inches under the ground. During a heavy rain, a saguaro will absorb as much water as its root system allows. 

To accommodate this potentially large influx of water, the pleats allow the flesh to soak up water, expanding like an accordion. Conversely, when the desert is dry, the saguaro uses its stored water and the pleats contract. 

 

Why are some saguaros crested?

Even when saguaro cacti grow in their normal form, they rarely grow symmetrically. Saguaros sometimes grow in odd or misshapen forms. The growing tip occasionally produces a fan-like form which is refered to as crested or cristate. Though these crested saguaros are somewhat rare, over 25 have been found within the boundaries of the park. Biologists disagree as to why some saguaros grow in this unusual form. Some speculate that it is a genetic mutation. Others say it is the result of a lightning strike or freeze damage. At this point we simply do not know what causes this rare, crested form. 

 

Do animals use the saguaro?

Saguaro cacti are host to a great variety of animals. For example, the gilded flicker and Gila woodpecker excavate nest cavities inside a saguaro's pulpy flesh. When a woodpecker abandons a cavity, elf owls, purple martins, finches and sparrows may move in. Saguaro cacti also provide a valuable source of food for animals. 

 

Do humans use the saguaro?

Archeological evidence indicates that the Hohokam people of the Tucson area used the saguaro in their daily lives. The strong, woody ribs were gathered to construct the framework for the walls of their homes. 

 

Are there threats to the saguaro?

The saguaro is a long-lived cactus, most affected by long-term climate cycles of frost and drought. Reports of a saguaro "disease" popularized almost fifty years ago, but saguaros are not subject to blights. The saguaro is a common plant in the Sonoran Dessert and is not an endangered species. 

Without question, the biggest threat to the saguaro is our rapidly expanding human population. The development of new homes in the Tucson area has resulted in a tremendous loss of saguaro habitat.