The Sonoran Desert is named for the
state of Sonora Mexico. It is found there and north into central Arizona and southeastern
California. This is a warm desert that lacks cold tolerant species. The rainfall
peaks in the winter months and during the summer monsoons. Cacti are well-represented
and are often the dominant life forms with a few well-know arborescent (tree-like)
species such as the saguaro. The Sonoran Desert can be divided into two distinct
vegetation types. The Arizona Uplands are characterized by a diverse low shrubland
of legume trees and many succulents. Some of the common legume shrubs are Parkinsonia
microphyla (foothills paloverde), P.
florida(blue paloverde--the state tree of Arizona), Olneya tesota
glandulosa (mesquite), Acacia greggii (cat-claw acacia), and
Calliandra eriophylla (fairy duster). Common cacti include the saguaro
barrel cactus (Ferocactus
wislizenii), and numerous chollas (Cylindropuntia
bigelovii , C.
acanthocarpa, C. fulgida, C. leptocaulis). Only one species of
splendens, is found in Arizona but others including the boojum can be
found south in Baja California, Mexico.