Parkinsonia & friends

Parkinsonia

A genus of 12 species of trees and shrubs native to warm and dry regions of North America. They make excellent landscape trees as well grown Parkinsonias are an unforgettable sight when in full bloom. These are some most unusual trees as the green bark continues the function of photosynthesis after the leaves have fallen. Close to 40% of photosyntheses of these trees is achieved this way. The Parkinsonia are also a food producing tree, the green immature seed pods can be harvested when they reach 3 inches, cooked before being eaten. The protein rich seed pods are tasty and high in protein ( up to 50 % ).
The Parkinsonias have potential as a food crop in arid climates where few trees other than Date Palms are grown as such.
They prefer moist, fertile, well drained soil in full sun in a position somewhat sheltered from wind. Very drought tolerant but all species grow faster and denser with irrigation. Rapid, deep root development is important to establishment. The roots on young plants grow around 0.3 inches per day with ideal conditions.
They are easy to grow from seed which is sown after nicking the impervious seed coat with a file and soaking for 12 hours. They can also be grown from softwood cuttings during summer or hardwood cuttings taken during autumn and protected from freezing during the first winter.
The Palo Verde Border may be an occasional pest, otherwise these trees are very easy to grow.

* photo of unknown internet source

* historic archive photo

Parkinsonia aculeata ( Jerusalem Thorn )
A very fast growing, graceful small to medium size evergreen tree reaching around 30 feet with slightly pendulous branches, that is native to stream banks of Mexico and the southwest U.S. from Arizona to Texas ( also found planted in parts of the southeastern U.S. ).
Some records include: fastest growth rate - 8 feet; 3 years - 17 x 10 feet; 4 years - 21 feet; 20 years - 20 x 20 feet ( average ); largest on record - 50 x 60 feet with a trunk diameter of 3 feet. It has been planted in many drier warm temperate to dry tropical areas around the world and in some places now grows wild. In Australia, it has become a highly invasive weed.
The paired long slender pinnate leaves, up to 5 or rarely 20 inches in length, that are composed of up to 60 narrow oblong leaflets up to 0.3 inches in length. The leaves fall during summers if it is dry, however the green stems carry out the role of photosynthesis.
The profuse golden-yellow flowers, up to 0.5 inches, are borne in clusters up to 7 inches in length during the spring if moisture is adequate.
Narrow seed pods up to 6 inches in length follow, these are typically constricted between the seeds.
The very attractive bark is bright green. The stems are armed with sharp spines at the base of the leaves.
Hardy zones 9 to 10 tolerating as low as 15 F preferring sandy, well drained soil that is somewhat moist.
Very heat, drought and salt tolerant. Jerusalem Thorn requires an average yearly rainfall exceeding 8 inches. It is also tolerant of sea breezes and is excellent for use by the sea. A seedling plant can become a saleable 5 gallon size plant in one year. Tolerant of drastic pruning. To speed up germination of seeds, soak them in 95% sulfuric acid for 30 minutes then rinse in cool water for 30 minutes before sowing.

* photos of unknown internet source

* historical archive photo

Parkinsonia 'Desert Museum'
A multi-species hybrid that is very fast growing and thornless with larger flowers.
With adundant moisture and warmth, it may be semi-evergreen.
Some records include: 2 years - 8 feet; 3 years - 11 feet; 4 years - 15 feet; 6 years - 20 feet; 10 years - 25 feet; 15 years - 30 feet; largest on record - 50 x 50 feet.
The leaves, up to 4 inches in length, are larger than that of most other Paloverdes.
The very profuse flowers are bright yellow.
The bark is smooth and lime green.
Hardy zones 8 to 10. No damage at 15 F in Tucson

Parkinsonia floridum ( Blue Paloverde )
A fast growing, medium-size tree native to the southwest U.S. from southern California, southern Nevada and central and southern Arizona; also in western Mexico. Some records include: 2 years - 7 feet; 3 years - 9 feet; 4 years - 8 x 15 feet; 5 years - 11 feet; 8 years - 17 feet; 12 years - 20 feet; largest on record - 55 x 50 feet with a trunk diameter of 2.7 feet; longest lived - 200 years.
It is leafless for most of the year, the foliage typically appears briefly in the spring then sometimes again in fall, however may be evergreen with abundant moisture and warmth. The foliage is pendulous. The bipinnate leaves, up to 1.5 inches in length, are composed of 2 pinnae, each having 4 or 6 oblong blue-green leaflets, up to 0.5 inches in length. Photosynthesis continues with the green bark after the leaves have fallen.
The very abundant masses of bright-yellow flowers, up to 1 inches across, are borne in racemes up to 4.5 inches in length during spring and sometimes again during autumn.
Flat yellow-brown, seedpods up to 3 inches in length follow.
The twigs are spined and the attractive bark is smooth and blue-green.
Hardy zone 8 to 11 tolerating as low as 10 F. It is more tolerant of irrigated lawns than other species, however too frequent watering can lead to a shallow root system and a tree that topples over.

* photo taken by F. Lee Kirby @ USDA-NRCS PLANTS Database

* photo taken by T.P. Lukens @ USDA-NRCS PLANTS Database

Parkinsonia microphylla ( Yellow Paloverde )
A fast growing small tree to around 20 feet that is native to the southwest U.S ( from southern California to central and southern Arizona; also occuring in the Baja Peninsula and northwest Mexico ). Some records include: fastest recorded growth rate - 3 feet; 3 years - 5 feet; largest on record - 53 x 50 feet with a trunk diameter of 1.8 feet. It can live up to 400 years.
The leaves, up to 1.5 or rarely 4 inches in length, have 2 pinnae each composed of 4 to 7 pairs of very small, elliptical leaflets. The leaves shed early, especially when dry. The foliage is yellow-green to bright-green.
The yellow flowers, up to 0.5 inches across, are borne in racemes during spring.
Cylindrical seedpods up to 3 inches in length follow. The seedpods constrict between the seeds.
The branches are tipped in sharp spines. The attractive bark is yellow-green.
Hardy zone 8b to 11 ( tolerating as low as 15 F ) in full sun on well drained soil. Extremely drought tolerant, it prefers occasional deep waterings and does not grow well in irrigated lawns.

* photo taken by Kenneth W. Parker @ USDA-NRCS PLANTS Database

* historic archive photo

Parkinsonia praecox ( Texas Paloverde )
A fast growing, thorny deciduous tree native to the southwestern U.S. and northwest Mexico with disjunct populations in Argentina. Some records include: fastest recorded growth rate - 3 feet; 2 years - 5 x 4 feet; 3 years - 7 feet; 6 years - 17 feet; largest on record - 40 x 40 feet with a trunk diameter of 1 foot. It is an excellent shade tree for desert climates.
The deep green pinnate leaves, up to an inch in length, are composed of tiny rounded leaflets.
The very beautiful yellow, funnel-shaped flowers are borne in loose sprays during spring.
The bark is gray-white.
Hardy zones 9 to 10 ( tolerating as low as 15 F for Sonoran populations and 10 F for Argentine populations ). The Argentine population is also more drought tolerant, surviving in places with as little as 4 inches of yearly rainfall in Argentina.
Easy to grow, it makes a great patio tree and problems are extremely rare.

Parkinsonia x sonorae ( Sonoran Palo Verde )
The hybrid between Parkinsonia microphylla & P. praecox, forming a fast growing, medium-sized tree. Some records include: 3 years - 7 feet; 8 years - 11 feet; 15 years - 20 feet; largest on record - unknown, estimated maximum size of 50 x 50 feet with great age.
The bark is smooth and bright green.
Hardy to 15 F at Tucson. A great tree for extremely hot urban sites such as shopping mall parking lots.

Parkinsonia texana ( Texas Paloverde )
A very fast growing, very spiny, rounded, small deciduous tree, reaching a maximum size of 25 x 20 feet, that is native to Texas and northeastern Mexico.
Some records include: 6 years - 7 feet.
In colder parts of its range, it can be grown as a perennial that is cut back to near ground level each winter and still reach 12 feet by the end of summer.
The leaves are composed of 2 to 3 small, oblong leaflets. The foliage is blue-green.
During severe drought, the leaves will often fall off with the tree releafing when heavy rains fall.
The flowers are yellow.
The smooth bark is green and provides photosyntheses while the tree is not in leaf.
Hardy zones 8b to 10 in full sun on alkaline, sandy, well drained soil. It has no damage at 15 F in Tucson but will be cut back to ground level at 9 F.

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Olneya tesota ( Desert Ironwood )
A moderate growing, multi-trunked, extremely long lived, dense, spreading, medium-size semi-evergreen ( drought deciduous ) tree to 25 feet that is native to the southern California desert, most of southwest Arizona ( including the entire Sonoran Desert ); south into Baja Peninsula and western Mexico. Some records include: fastest recorded growth rate - 2 feet; first year - 10 inches; 3 years - 3.5 feet; 5 years - 6 feet; 8 years - 12 feet; 12 years - 18 feet; 15 years - 20 feet; 50 years - 35 x 45 feet; largest on record - 60 x 80 feet with a trunk diameter of 5.3 feet ( potential to grow much larger in cultivation with occasional irrigation ); longest lived - 1500 years. This tree is very important for wildlife habitat where it grows native.
The pinnate leaves, up to 2 x 1 inches, are composed of 10 to 20 oval leaflets, up to 0.7 inches in length. The foliage is silvery to gray-green and surprisingly lush considering the trees native habitat. This very beautiful tree looks like a Russian Olive tree from a distance.
The showy white or pink flowers are borne in clusters at the stem tips from mid spring into early summer, shortly before the new foliage emerges. A new variety has rosey-purple flowers that are much showier.
The seeds were used as food by the natives. The seed was ground into meal then boiled to get rid of the bitter taste. The immature green seeds can also be boiled in water then eaten.
The thorns are vicious which is this trees only drawback.
The bark is smooth and grayish-green on young trees; turning darker gray, shredded and rough on old trees. The wood weighs around 66 pounds per square foot, the heaviest of all North American trees, the wood does not float in water.
The wood is very hard and used for tool handles.
Hardy north to zone 9. Some damage at 15 F in Tucson. Very heat and drought tolerant.

* photo of unknown internet source

* historic archive photo

* excellent video found on internet


'AZT'
Faster growing and more upright with white bark.