Blue Paloverde State Tree of Arizona

The state tree of Arizona is the Blue Paloverde (Parkinsonia florida). This striking tree is also known as Cercidium floridum. It is found growing in Arizona, Nevada, and California. The paloverde can grow to 30 feet tall with a trunk diameter of 1 1/2 feet. Look for this tree in valleys and desert grasslands, as well as in areas of a desert floodplain where the runoff collects.

The leaves of the paloverde are very small and rounded. They form on short twigs close to the branch. From a distance, the tree appears feathery and wispy. The trees are leafless for most of the year, especially during drought conditions. This leafing behavior is referred to as drought deciduous. There is also a straight spine that grows at the leaf nodes.

There is a very bright yellow flower, approximately 1 inch wide, that opens in early spring. When the tree is in bloom, the open branched shape resembles a bouquet.

The truck has multiple branches that form close to the ground. The spread is wide relative to the height. The upper trunk and branches are a blue-green color. It is the blue-green branches and twigs that produce the food for the tree. The markings on the bark resemble those on birch trees.

The Blue paloverde is a garden option for dry conditions. It is sometimes recommended as a replacement for the invasive black locust. The tree has a beneficial purpose for controlling soil erosion in areas that experience periodic flooding. The shrub-like tree is a fast grower and develops a deep root system that aids water sourcing and ground stabilization. It grows is high temperature areas from sea level up to 4,000 feet. It will tolerate poor soil, including sand and gravel.

The paloverde has a long history in the Southwest desert region of the US. Plant historians date its emergence over 4,000 years ago. Early people cooked the immature fruit for food and ground the seeds to make a flour. In modern times, local animals are seen feeding on the twigs and seed pods. This includes mule deer, bighorn sheep, and burros. Birds and small rodents are fond of the seeds, and several bird species use the trees for nesting.

The paloverde is often seen growing with ironwood and jojoba (Simmondsia chinensis). The wood is considered useful as a fuel source.

Sources
Parkinsonia florida, Lady Bird Johnson Wildflower Center, http://www.wildflower.org/plants/result.php?id_plant=PAFL6
Parkinsonia florida, University of Arizona, http://ag.arizona.edu/arboretum/taxa/Parkinsonia_florida.html
Parkinsonia florida, US Forest Service, http://www.fs.fed.us/database/feis/plants/tree/parflo/all.html