Who could not show appreciation for Arizona's Official State Tree, the Palo Verde, especially when covered in a bevy of brilliant yellow flowers.

Friday, April 29, is Arbor Day in Arizona … a day to appreciate the trees we see regularly, to prize the shade they provide, to re-think the value they add to our lives.

Currently brightening our desert are the catkin-like yellow and cream blooms on varieties of Mesquite, the petite golden balls of Acacias, and the thousands of vivid yellow petals on Arizona’s official State Tree, the Palo Verde. The air has been permeated with the soft sweet scents of tree blossoms.

In the desert, trees are invaluable for providing shade, which shaves numbers from the thermometer during hot summers. Trees also reduce noise pollution, such as from heavy traffic. They provide wind protection. Trees absorb harmful pollutants and small particles from the air which could damage our lungs. Their photosynthesis gives off oxygen. University studies have shown that one large tree can provide a day’s supply of oxygen for up to four people.

Most desert trees belong to the legume family, meaning they produce their own nitrogen with the aid of soil micro-organisms. After flowering, pods are created, differing by variety as much as do the flowers. Some trees are known for making more litter than others.

Perhaps this is a good time to consider planting a tree, but first do some homework.

Ask questions such as: “How much space is available for the mature tree? How much litter can be tolerated? What maintenance level can be provided? Will there be a neighborhood view issue as the tree grows?”

All trees eventually need some trimming and cleanup, but some require less work than others. Experience has found that native choices have adapted to the desert climate, are lower water users, are not as affected by insects and disease, thrive in our alkaline soil, and overall require less care.

Arbor Day can also be celebrated without planting a tree. Take the opportunity to inspect your existing trees, noting any broken limbs, rubbing branches, or evidence of disease or insects. Give thought to how added trees might improve the appearance of your property, provide more privacy, and give needed wind or sun protection.

For a day trip to an arboretum, consider Boyce Thompson at Superior. In the Santa Cruz Valley, visit Tohono Chul Park or Tucson Botanical Gardens. Why not take a walk around the University of Arizona main campus, which is a Certified Arboretum with a wide variety of identified trees.

Whatever you choose, enjoy Arbor Day in Arizona this year!

Mary Kidnocker is a University of Arizona Master Gardener who lives Southern Arizona.

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