Saturday, April 28, 2012

The Yellow Moment

There comes a day in April in Tucson when you look around and the entire world is YELLOW; very, very yellow.  And such it is at this moment in time.

It's as though a giant artist has dipped her brush in a big pot of yellow paint and swiped it across the landscape, as far as the eye can see.  For a few glorious days, up to two weeks, the desert will be awash in color.  And then it will be gone, seemingly as quickly as it arrived.  The moment will have passed.  Just as the setting sun paints the mountains in shades of pink and purple in "the pink moment" and then fades away, so too will these colors be gone and slip into our memory.

Palo verdes are by far the most dominant tree in the Arizona upland, and it is the annual bloom of this tree which colors our world.  Several species of palo verde can be found growing around Tucson, including the Foothill (Parkinsonia microphylla), Blue (Parkinsonia florida), Mexican (Parkinsonia aculeata) and several hybrids.   Like most of the Sonoran desert trees north of the Mexican border, palo verdes are legumes, in the family Fabaceae.  Most of you are familiar with legumes due to their common and widespread use for food (think peas and beans).  It's a huge family of 16,000 species, many of which are found in the arid tropics.
Foothill Palo Verde, agave stalk and white-winged dove.
Those of you who know Spanish can figure out that palo verde means 'green stick'.  Sure enough, if you look at the bark, you will see that it is green.  This is a wonderful adaptation to drought.  The tiny leaves fall off during times of drought, so the green bark allows the tree to photosynthesize without the leaves.

But it's the flowers, blooming in such profusion that they completely hide the leaves and branches, which are our focus today.  Flowers in the subfamily Caesalpinia have five separate petals, one of which, the 'banner' petal, is always a little different than the others.  It may be larger, or a different color.  Another characteristic is the 10 separate stamens.  The first to bloom are the Blue PV's, with their deep yellow hue.  All the petals are yellow, but the banner petal is slightly larger and has tiny orange dots.
Blue Palo Verde 
Just as the flowers of the blue palo verde are fading and falling to the ground, the foothill palo verde begins its bloom.  In the areas where the bloom overlaps, it is easy to distinguish the two.  The flowers are much paler yellow in the Foothill PV.  Four of the petals are pale yellow and the banner petal is white.
Closeup of the Foothill Palo Verde flower
More drought resistant than its cousin, the Blue, the foothill grows happily on rocky hillsides, whereas the Blue is more at home in washes where it might receive more regular water.  Foothill can also long outlive the blue.  The flowers of the palo verdes are pollinated by solitary bees.  All species of palo verde produce bean pods following the bloom, which are nutritious and delicious to many animals.

Although palo verdes provide the BIG yellow, many smaller desert plants are also now in bloom and they add their shade of yellow to the sunshiny scene.

Engelmann's Prickly Pear Cactus
Santa Rita Prickly Pear Cactus
Cholla Cactus
Prickly Pear Cactus
Agave Flower
Octopus Agave bloom
Cooper's Paper Flower
Desert Marigold
See what I mean?  Yellow.  Lots and lots of yellow.  Do you think I'm tired of it?  Not a chance.
I leave you with a shot of my back yard and the view toward the Catalinas.  And now I'm going to go out and enjoy it some more!


  1. Absolutely beautiful Carole. The yellow weeks are some of the finest we get to enjoy in Arizona. The yellow monoliths are a treasure to be cherished in themselves, and yet they still bring in all manner of other colorful birds and bugs!

  2. Thanks a lot to share this yellow beauty! (In fact, yellow is my favourite colour!) ;)

  3. Thanks for the info Carole! Now I know which palo verde has the bright flowers and which one has the lighter ones. You answered the question I asked myself yesterday while driving to Mt. Lemmon.

  4. So beautiful - the best 'flowering' year, I think, since I have been here.

  5. Carole, Just beautiful. We just came back from CO and driving through NM. When we arrived home, in Tucson, it was sensory overload....... the the yellow. After being amongst trees and rock, which was beautiful, the yellow trees and flowers were just beautiful.

  6. All of that yellow is just stunning!! You certainly shared some golden moments with us!! What a way to brighten our day!

  7. Wonderful theme today!!! It is so gorgeous here right now. The Desert Willow with the pink, palo verde and the yellow....and soon my Jacaranda with its violet. Best time of year besides November. Love your Agave bloom!!!

  8. I love yellow! It's such a cheerful colour and of course reminds me of the sun which we don't see often enough here. Your interesting post and lovely sunny photos are very uplifting on yet anothere wet and miserable day here! The Agave flower against the beautiful blue sky is wonderful.

    So sorry not to have commented for a while Carole but I have enjoyed your posts.

  9. All that is wrong with your posts is that they are too rare. Of course all of them are give us rare views into your world. Thanks for sharing.

    Here, at Malheur, we are in the yellow-fringed stage - we see tiny bits of yellow in the golden currents, dandalions, and another shrub that I've only found at headquarters and haven't learned its name. But we are also getting bits of bright green - the grasses are greening up and the tiny leaves of the greasewood are green.

  10. The blooming Palo Verdes sure are spectacular this year. Your photos are beautiful, great series of yellow flowers!

  11. I do miss the blooming of the desert! Thanks for sharing it with me.

  12. I was thinking of you early this morning when I stepped out my door and everything that was in bloom was purple! My rock garden is (almost) all natural, and with the exception of a few early blooming daisies, purple dominated. I remembered this post about everything being yellow. I see I'm not the only one who hasn't been blogging lately! Hope you are too busy having fun! ~karen


I welcome your comments, but those from Anonymous users, or those including links will be immediately reported as Spam to Blogger and will be deleted. Thanks for your understanding.