The Sonoran Desert is synonymous with cacti, and a wide diversity of species can be seen here.
The Sonoran Desert occupies the central and south-western third of Arizona. It is lower in elevation than the Chihuahuan & Mojave deserts and hence has a milder climate, although snow can fall in extreme winters.
The climate of the Sonoran Desert presents a huge challenge to plant life - each species must be tough enough to withstand high temperatures in summer, and months without any rain. Many plants have achieved this, and thrive in this corner of Arizona.
Various forms of pine-oak woodland cover many of Arizona's mountain ranges. The range of species varies with location, elevation and aspect. Arizona's mountains mark the boundary of the Madrean and Rocky Mountain floras.
Grasslands in Arizona tend to be at high altitude, with a flora resembling that of the colder Chihuahuan Desert. Riparian areas are oases of life - these tree-lined habitats have a rich flora more typical of the cooler Rocky Mountains and eastern states.