The state tree of Arizona is the palo verde. Although there are two species of palo verde, the legislation designating the palo verde the state tree of Arizona in 1954 didn’t specify which species. Cercidium floridum, also known as the blue palo verde, has leaves and branches colored a bluish green. The other species of palo verde is Cercidium microphyllum, commonly known as the foothill palo verde. This species sports branches and leaves that are a yellowish green.
Both species of palo verde are native to the American southwest and northern Mexico, and both can be found in Arizona. They are deciduous trees that shed their leaves during times of drought. When the trees are bare of leaves, the green branches take over the function of photosynthesis, allowing the tree to thrive in hot, dry, desert conditions.
The palo verde brightens up the landscape in the spring when it blooms from late March through May with a profusion of yellow flowers. Each flower is solitary and approximately 1 inch (2.5 centimeters) in diameter. The palo verde may not bloom every year since blossoms are dependent on the amount of rain the tree receives. A mature palo verde can attain a height of around 25 feet (7.6 meters) with an equally wide spreading canopy and a trunk diameter of 1.5 to 2 feet (0.4 to 0.6 meters). It has a deep root system to reach any underground water in the vicinity.
Leaves of the state tree of Arizona are food for jackrabbits, mule deer, bighorn sheep, and various rodents, while the seed pods are preferred by javelinas. Their canopy provides shade and the lower temperatures required for the germination of other desert plants such as the saguaro cactus. Seeds of the state tree of Arizona have been used by some Native Americans to make necklaces, and they used both the seeds and flowers as food. The flowers can be used to make red dye, and the wood is used as firewood.
Palo verde means green stick in Spanish. The state tree of Arizona received this name because of its green bark, which gets its color from its high chlorophyll content. It propagates from the seeds which are produced after a cool, wet spring and are food for rodents, who often bury the seeds for safekeeping. Young palo verde seedlings are not drought-tolerant. Some of the seeds may germinate after a rainfall, but very few survive the arid conditions.