Cacti

Over time, cacti evolved to survive in their various environments. Not all species live in dry desert areas. They range from South America to Canada, in tropics, mountains, beaches, grasslands, and deserts, and can be found from sea level to near 10,000' in elevation.

Survival in the Sonoran Desert requires adaptation to extremes in water availability. During times of plenty, shallow roots quickly soak up the rain, storing it in the cacti's expandable tissues. Just as important are the plant's drought adaptations. Waxy outer skin and the lack of leaves help reduce evaporation. In addition to guarding the cacti from hungry animals, spines break up wind currents and shade the skin from sunburn. Food production and respiration, normally occurring in leaves, take place in the stems or pads of the cacti.

Due to its ability to store moisture, a cactus can flower even in years of poor rain, ensuring future survival. The bright color of the resulting fruit attracts hungry animals. Some of the seeds are dispersed in the shelter of a nurse plant. There a new cactus can grow undisturbed until it can fend for itself.

For more information and pictures about individual species of cactus, visit Tonto National Monument's Virtual Tours, especially the Cactus Patch Trail.

Recommendations from our bookstore:
A Natural History of the Sonoran Desert edited by Steven J. Phillips and Patricia Wentworth Comus
Cactus Hotel by Brenda Z Guiberson; illustrated by Megan Lloyd
What Kinda Cactus Izzat? by Reg Manning
70 Common Cacti of the Southwest by Pierre C. Fischer