Cacti, shrubs, and trees grow in abundance in the Sonoran Desert. Temperatures in the Sonoran Desert can reach 120 degrees Fahrenheit and rainfall is less than 10 inches per year. Plants in the desert need to adapt to an environment of little rain and very hot temperatures.
It takes thousands of years and many generations to change what a plant looks like and how it functions. Cacti adapted to the arid land by being able to store large amounts of water in their flesh. Their leaves became spines to help reduce evaporation and discourage animals from eating them. Some shrubs, like the saltbush, have silvery leaves that help retain moisture. The ocotillo and creosote bush lose their leaves entirely during drought periods, reducing moisture loss.