Palo Verde Trees are desert superstars for a plethora of reasons, but most notably their extreme resistance to heat and drought, low water requirements, nitrogen fixing capabilities and ability to provide shade, shelter and habitat to other desert flora and fauna. Once recognized under the Genus Cercidium, they are now classified as Parkinsonia. They are considered one of the primary ‘Nurse’ plants and keystone species of the Sonoran Desert, protecting Saguaro Cacti and other native yucca, agave and cacti while they are immature and vulnerable to the vagaries of a harsh and unforgiving climate. They are an excellent choice for dry-land gardeners, with their iconic green skinned trunk and profusion of pea-like, buttery yellow flowers each Spring. They cope with drought and cold by shedding their leaves, relying on their chlorophyll rich green trunk and branches to process the suns energy, lending wonderful aesthetic structural interest to the landscape even in their deciduous, leafless state. Bees love the blossoms for making honey, and different species can easily hybridize if planted in close proximity. Good drainage is essential, especially if they are irrigated with any regularity. They are quite cold hardy when dry, and are best adapted to arid climates.
Click here for more information about how to germinate Palo Verde Trees from seed.
Blue Palo Verde
Latin Names: Parkinsonia florida, Cercidium floridum
Common Names: Blue Palo Verde
USDA Zones 8-11
Category: Deciduous Tree
Height: 30-50′
Width: 30-50′
Exposure: Full Sun
Origin: Southwest United States and Mexico
Irrigation: Low Water
Cold Hardiness: 15-20 F
Bloom Color: Bright Yellow
Bloom Time: Spring (usually March/April)
Blue and Foothill Palo Verdes are the Arizona State Tree. This fast growing species naturally tends to grow in bajadas, basins and watersheds. Their coloration is more blueish, and they have small thorny spines at the branching points. They tend to be the first of the Palo Verdes to bloom in Spring. They usually live 30-50 years, though some specimens are much older.
Foothill Palo Verde
Latin Names: Parkinsonia microphylla, Cercidium microphyllum
Common Names: Foothill Palo Verde, Littleleaf Palo Verde, Yellow Palo Verde
USDA Zones 8-11
Category: Deciduous Tree
Height: 10-20′
Width: 10-20′
Exposure: Full Sun
Origin: Southwest United States and Mexico
Irrigation: Low Water
Cold Hardiness: 15-20 F
Bloom Color: Light Yellow w/ One White Petal
Bloom Time: Spring (usually April/May)
Foothill and Blue Palo Verdes are the Arizona State Tree. Foothill or Littleleaf Palo Verdes have a smaller, more shrub-like habit. This slow-growing species naturally tends to grow on rocky slopes. They tend to have more of a yellowish coloration, with smaller leaves than the Blue Palo Verdes, and they are even more drought tolerant due to their slower rate of growth. Small thorny spines adorn the tips of the branches, so avoid planting close to walkways. They can live over 200 years in their native environment.
Palo Brea
Latin Names: Parkinsonia praecox, Cercidium praecox
Common Names: Palo Brea, Sonoran Palo Verde
USDA Zones 9-11
Category: Deciduous Tree
Height: 20-30′
Width: 20-25′
Exposure: Full Sun
Origin: South America and Mexico
Irrigation: Low Water
Cold Hardiness: 20 F
Bloom Color: Yellow
Bloom Time: Spring
The smooth-barked Palo Breas are often considered the most sculptural of the Palo Verdes, avoid planting along streets or in parking lots where they would need to be over-pruned. This species grows at a moderate rate.
Mexican Palo Verde
Latin Names: Parkinsonia aculeata, Cercidium aculeata
Common Names: Mexican Palo Verde, Jerusalem Thorn, Retama, Palo de Rayo, Horsebean
USDA Zones 8-11
Category: Deciduous Tree
Height: 10-20′
Width: 10-20′
Exposure: Full Sun
Origin: Southwest United States, Mexico,
Irrigation: Low Water
Cold Hardiness: 15-20 F
Bloom Color: Yellow
Bloom Time: Spring
While Mexican Palo Verde can be a nice landscape tree, in areas where it thrives it is considered a highly invasive species, one of the most invasive weeds of Australia as well as problematic in Africa, Hawaii, and other Island ecosystems. They are not considered an ideal landscape specimen because of their thorniness, messy leaf litter (though all Palo Verdes except ‘Desert Museum’ can be pretty messy), and short-lived nature. Their ability to aggressively reseed in hot, arid environments makes them prone to forming deep and impenetrable thickets that can block waterways.
Desert Museum Palo Verde
Latin Names: Parkinsonia x ‘Desert Museum’
Common Names: Desert Museum Palo Verde
USDA Zones 8-11
Category: Deciduous Tree
Height: 30′
Width: 30′
Exposure: Full Sun
Origin: Southwest United States, Mexico,
Irrigation: Low Water
Cold Hardiness: 15-20 F
Bloom Color: Yellow
Bloom Time: Spring
Desert Museum Palo Verdes were hybridized at the Arizona Sonora Desert Museum from a batch of P. florida x P. microphylla x P. aculeata seedlings grown by Mark Dimmitt. They are fast becoming the most popular landscape variety because they have been bred to have the best qualities of all their parent plants, growing quickly, with large showy blossoms, a longer bloom season and they are thornless to boot! These will not bear seeds true to type.
I will continue to update with more photos and information about each species over time.
You can find desert-adapted plants and seeds I grow here in my shop.
