Arizona doesn’t generally get a lot of rain, so you don’t have the towering trees or the amount of greenery that you see in some parts of the country.
As you drive north from Phoenix, you also go up in elevation. You leave behind the saguaros and see more trees and, eventually, the red rocks of the area around Sedona.
Along the way, you pass by the Prescott National Forest to the west.
Here is a description from the United States Forest Service:
“At the lowest elevation, the primary vegetation is of the Sonoran Desert type. As the elevation rises, chaparral becomes common, followed by piñon pine and juniper. Above that, Ponderosa pine dominates the landscape.”