Blue Palo Verde (Parkinsonia florida)

When people think of the Sonoran desert, hillsides studded with saguaro cactus and cholla often come to mind.   But interspersed between the cactus, you will find the iconic palo verde trees with their beautiful green trunks and branches.

The word “Palo Verde” means “green stick” in Spanish, referring to their green trunk, which is a survival mechanism in response to drought.  
 
Palo verde trees are “drought deciduous,” which means that they will drop their leaves in response to a drought situation.  Their green trunks and branches can carry on photosynthesis, even in the absence of leaves. 

‘Desert Museum’ Palo Verde (Parkinsonia hybrid ‘Desert Museum’)

Palo verde trees act as a “nurse plant” to young saguaro cacti by protecting them from the cold in the winter and from the intense sun in the summer.  Beautiful, yellow flowers are the product in the spring.    

  ‘Desert Museum’ Flower
There are three species of palo verde that are native to the desert Southwest; blue palo verde (Parkinsonia florida), formerly (Cercidium floridum), foothill palo verde (Parkinsonia microphylla), formerly (Cercidium microphyllum) and ‘desert museum’ palo verde (Parkinsonia x ‘Desert Museum’)
 

Another species of palo verde that is prevalent in the landscape are called palo brea (Parkinsonia praecox), formerly (Cercidium praecox).  They have a dusty green trunk and branches that twist and turn.  Their cold hardiness range is around 15 to 20 degrees F.

Palo Brea
PALO VERDE USES: Palo verde trees serve as beautiful specimen trees where their green trunks, branch structure, and flowers serve as an attractive focal point in the landscape.  They are drought tolerant, once established and provide lovely filtered shade year-round.  
 
When deciding where to place your tree, be sure to take into account that they need a lot of room to grow, mature sizes are listed below.  
 
Palo Verdes don’t do well when planted in grass and will decline over time.  Locate away from swimming pools due to flower litter in the spring.
Because of their more massive thorns and branching tendency to point downwards, palo brea trees aren’t recommended in areas close to foot traffic.  
  
Mature Sizes:
Blue Palo Verde – 30 ft x 30 ft
‘Desert Museum’ Palo Verde – 30 ft high x 40 ft wide
Palo Brea – 30 ft x 25 ft
Foothills Palo Verde – 20 ft x 20 ft
As with many desert trees, Palo Verde trees have thorns, except for the ‘Desert Museum’ Palo Verde.  

Foothills Palo Verde
PALO VERDE MAINTENANCE:  Prune to elevate the canopy and maintain good structure.  Avoid hedging and “topping” trees as this stimulates excess, weak growth.
 
MY FAVORITE: As a landscape manager, horticulturist and arborist, I have grown and maintained all of the palo verde species mentioned, and I truly enjoy them all.  However, at home, I have 4 ‘Desert Museum’ trees.  In comparison to the other species, their trunks are a deeper green; they produce larger flowers, are thornless and grow very quickly in the desert.  Also, they require little, if any, tree staking when planted. 

The blooming of my desert willow tree (Chilopsis linearis), is beginning to slow down.  The leaves will fall in December.  However, there were a few lovely pink flowers left.

Also, the recent monsoon storms have caused my ‘Rio Bravo’ sage, (Leucophyllum langmaniae), to burst out in flower.

Beautiful, magenta brachts surrounding the tiny, cream-colored flowers on my single bougainvillea shrub.

I also love the multi-colored blooms of my lantana ‘Patriot Desert Sunset.’  They will soon stop blooming for the winter.

The vibrant colors of my red bird-of-paradise, (Caesalpinia pulcherrima) add vibrant color to my garden and nectar for hummingbirds.  


In another month, many of these flowers will no longer be flowering, but until then, I’ll enjoy the view.

This beautiful plant is one of my favorite shrubs in the garden – so much so, that I have three.  Yellow bells produce bell-shaped flowers beginning in spring and lasting through the fall months until the first frost.
 
 Hummingbirds and butterflies are attracted to the flowers.  The vibrant green foliage and colorful flowers make this shrub a welcome addition to any desert landscape. 

Yellow Bells is a large shrub that grows to a height of 4 – 8 ft. and spreads 3 – 8 ft. wide.  You can find its native habitat in the Americas.  There are two different types; Tecoma stans angustata and Tecoma stans stans.  Visually, the most significant difference is in the shape of the leaves.  Tecoma stans stans had a broader leaf and are pictured above and below.

USES:

Because of its size, this large shrub makes a great backdrop plant.  I have used it to screen fences, sheds and also planted it up against the house.  Yellow Bells works well as a tall, naturally-shaped hedge.  This shrub thrives in full sun to filtered shade.  They do best in warm-winter areas but can be successful as a summer annual in colder regions.

MAINTENANCE:

This shrub is relatively low-maintenance.  It will freeze back in the winter months when temperatures go below 28 degrees F.  Since it blooms on current season’s growth, all that is required is to prune back the frost damage in early spring.  Seed pods are produced and can be removed if desired, which will extend the bloom period and improve the appearance, (the seed pods do not bother me, and I do not remove mine).   After an initial application of slow-release fertilizer when planting Yellow Bells, I have not needed to fertilize further. 

**Occasionally, caterpillars will appear but can be easily removed by spraying some BT (Bacillus thuringiensis) which is an organic pesticide.

 
 

COMMON NAMES: 

There are many familiar names for these beautiful shrubs.  Tecoma stans angustata is native to the Southwestern US and northern Mexico and goes by the names Arizona yellow bells, yellow bells, and yellow trumpet bush. 
 
Tecoma stans stans are native to Florida, the Caribbean and parts of South America and also goes by the name of yellow bells and sometimes yellow elder.  Because of the overlap of familiar names, be sure to purchase plants based on their scientific name.

I just had to share this photo of my flowering Arizona fishhook cactus(Mammillaria grahamii) also known as (Mammillaria microcarpa).

While walking outside in the garden this morning, I caught a glimpse of pink off in the distance. As I went over to explore further, I noticed my little Arizona fishhook cactus in full bloom. I don’t have many cacti in my garden, but even if I did, this little one would probably still be my favorite. 

Pink crowns of flowers appear off an on throughout the summer months in response to rain much to the delight of native bees.

I found this little cactus growing alongside a large boulder in an area of desert that was getting ready to be graded for a new house. At the time my crew and I were digging up different types of cacti, like barrel cacti and teddy bear cholla, to relocate them around the site out of harm’s way. I received permission to keep this little one.

One of the things that I love about this little cactus is it flowers off and on during the summer months in response to rain or a small amount of water from my garden hose.

Look closely at the spines, you can see where it gets its common name with their fishhook shape.

Believe it or not, I can hold this cactus (carefully) without getting pricked.

During the rest of the year, this small cactus fades into the background and is hard to see.  You can find it growing underneath bursage shrubs throughout the desert.

Do you have a favorite flowering cactus in your garden?