Arbor Day is celebrated in Arizona on the last Friday in April. Arbor Day is not a national holiday, but was decided on a state-by-state basis. Sadly, the State Legislature picked the date without asking us folks that work with plants. In most of Arizona, one should ideally plant trees in autumn or in January, so they can become well-established with a healthy widespread root system before the searing summer heat.
Personally, I think we should petition to change the celebration to the first of October. That date would work for all our growing regions, be easy to remember, plus make us the only state to celebrate in that month, further highlighting our uniqueness.
Be that as it may, you could plant a tree next Friday, as long as you are prepared to pamper it through the summer to help it get established. This column discusses some trees that will do well here and fit in the smaller yards many readers have. (Acacias were discussed in 2009; let’s move on to the next letter of the alphabet.)
Bauhinias have leaves shaped like butterflies. Some large species come from China and are high water users. Chihuahuan Desert species such as anacacho (Bauhinia lunarioides, was B. congesta) and the Mexican orchid tree (B. mexicana) use less water and fit well in smaller spaces.
Both flower intermittently through the warm months with orchid-like flowers. Both species reach around 15 feet tall, and confusingly both come in white and pink varieties. The main difference is in the degree of shrubbiness, with anacacho needing a great deal of attention when young to be trained into tree form.
The yet hard-to-find retuma (Bulnesia retuma) comes to us from South America. It is a fast grower, quickly reaching mature size of around 15 feet tall and wide, then it grows only a little each year. This thornless single-trunked tree is adorned with very pretty hops-like papery fruits in fall.
Most people are familiar with the red bird of paradise that generally freezes to the ground in winter. It’s from the West Indies, so can you blame it for finding our winters cold? In the same genus are two species from Mexico that don’t freeze back in our area and can be trained into lovely multi-trunked trees.
Cascalote (Caesalpinia cacalaco), reaching 15 feet, has bright green leaves, bright yellow blooms and thorns. Mexican bird of paradise (Caesalpinia mexicana) reaches around 12 feet in height with similar bright green leaves and glorious yellow blooms that appear intermittently throughout the warm months. Less common, but worth the search are the copper caesalpinia (C. pumila), also to around 15 feet, and the taller palo colorado (C. platyloba), reaching 20 to 25 feet.
Often overlooked when selecting trees is a native ideally adapted to live here. Foothills palo verde (Cercidium microphyllum) has an attractive multi-trunked form that reaches around 20 tall and wide. The lovely yellow blooms are often falsely blamed for allergies since they appear in the same season as desert ragweed, whose pollen blows for miles. Larger and less messy is the ‘Desert Museum’ hybrid palo verde. As a hybrid it doesn’t produce seed, and reaches 30 feet high and wide.
Gee, I covered B and C, and yet there is a whole alphabet still to go! Stay tuned to these pages.
Jacqueline’s new book (“Father Kino’s Herbs: Growing & Using Them Today”) is now available for sale. Send your email address to firstname.lastname@example.org to receive more information on where the book is currently available.