Wednesday, March 18, 2009

Palo Verde Tree

"Nature, to be commanded, must be obeyed. "
-- Francis Bacon

People who live in the North American southwest in sprawling Sonoran Desert know the yellow flowers of the Palo Verde (Fabaceae, Parkinsonia florida, (Cercidium floridum)) tree as harbinger of Spring in our region. We celebrate these yellow flowers the way the yellow forsythia flowers are welcomed as Spring heralds in the east. The trunks and branches of Palo Verde (green stick) trees are indeed green, although the trunk tends to mellow to a soft gray with age. Because the pinnate leaves of these species are so tiny, the green branches aid in photosynthesis. Palo Verde trees are drought deciduous, and can even drop smaller branches to survive. Their yellow flowers show off from March through May, attracting pollinators like beetles, flies and bees, thus inviting birds to forage and nest in its branches.

And it's not just useful to the critters. According to The Living Desert: “The Cahuilla Indians were known to harvest the seeds during the months of July to August. The seeds were dried and ground in mortars to produce a flour which could be used to make a mush or to make cakes. Palo Verde seeds were also a known food source for the Pima and Papago Indians of Arizona.“

Pictured here are the two Palo Verde (either Blue Palo Verde or Mexican Palo Verde (Parkinsonia aculeata) trees in the Water Conservation Garden last spring. The flowers are a uniform yellow.

As you can see from close-up blooms of the ‘Desert Museum’ hybrid at The Garden (pictured below), have some orange, making the overall color richer. The best thing about the Desert Museum however, is that unlike its cousins, it is thornless.

So, where did the thornless hybrid come from? It’s name tells us. According to Arid Zone Trees:
“In the late 1970's Mark Dimmitt with the Arizona Sonora Desert Museum (ASDM) began noticing Blue Palo Verdes that exhibited characteristics suggesting they were hybrids of other Palo Verde species. He collected and planted seeds from the assorted trees he had observed and began evaluating them. By 1981 he had identified a thornless seedling as clearly superior to the others collected. Careful evaluation of the genetic composition of this hybrid, named 'Desert Museum', revealed it to be a complex hybrid having genetic characteristics from Mexican, Blue and Foothill Palo Verde.”

I intended to plant my tree in my mostly sunny front yard, where the steep terrain would provide good drainage and allow the roots to spread out and find their own water. We recently chopped down the old dead tangerine tree, and knowing there’s a sprinkler head in the planter area, I figured this would be a good home for my Desert Museum specimen. Boy, was I wrong. The railroad ties apparently collect all the heavy clay, making the spot a muddy pit that would almost certainly drown the poor roots.

One site I found researching the matter, said they shouldn’t be too near a water source as they prefer to seek out their own supplies. So, I’ll obey nature and find another home for it.


TC said...

I have several little trees, saplings if you will, that I plan on setting in around the yard this year. I just hope the deer don't bother them.

I hope your new tree does well.

Cicero Sings said...

Best laid plans of man gone afoul ... plants have their own ideas!

Martha in Michigan said...

How exciting! I share in your triumph at finding the perfect species for your exacting environment. And I recall the surprises in digging holes for the 20-or-so trees and shrubs I've planted here over nearly 30 years. The worst was discovering, two feet down in several places, a horizontal concrete barrier that we could only guess was a discarded screw-up when basement walls were poured. The third time I hit it, I completely changed my mind about where that tree should go! Wonder if it was someone's circa-1962 bomb shelter?

Jeri in Florence, AZ said...

When we moved our 40' 5th wheel trailer into its homebase lot in the Sonoran desert, we were fortunate to have a young pre-planted palo verde which was completely yellow in April attracting polinating bees. I was told to trim all branches that begin drooping downwards, that way the tree will develop a healthy canopy as it grows taller.

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