Flora of the Sonoran Desert

[1]: 3  Flora of the Arizona Upland are comparatively lush, with trees and large columnar cacti that can withstand winter frosts.

Annual plants mostly germinating during winter-spring precipitation tend to have closer affinities to flora of the Mojave Desert.

[2]: 7 Common plants are the burrobush shrub (Ambrosia dumosa), giving a grayish cast to the viewscape, and creosotebush (Larrea tridentata).

In areas of intermittent water steams (desert dry wash), ironwood (Olneya tesota), yellow paloverde (Parkinsonia microphylla), and Smoketree (Psorothamnus spinosus) can be found.

[2]: 5, 187  There are extensive stands of velvet mesquite (Prosopis velutina) in the valleys of the Arizona Upland, where colder air collects.