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.

RELATED PLANTS

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.

Needle Palm

Rhapidophyllum hystrix ( Needle Palm )

A suckering clump Palm, native to the Florida panhandle, that is usually slow growing but recorded growing as fast as 5 feet tall and wide in 3 years on ideal sites. It can reach 6 feet tall and 8 feet wide in 10 years or 10 feet tall and 16 feet wide in 50 years. The largest recorded is 14 feet in height. The trunk typically grows no taller than 12 inches in height. The fan shaped leaves are up to 5 ( rarely over 3 ) feet across and borne on stalks up to 7 feet long.
Each leaf is composed of up to 20 leaflets which are dark green above and silvery below. It is hardy north to zone 6 and reported to survive as low as - 26 F though with severe leaf dieback. Has been grown successfully on protected sites in northern Ohio and Michigan and survived in Colorado Springs, CO. Endangered in wild in its native southern U.S.A.! The Needle Palm requires hot summers with temperatures reaching up to the 90s on a regular basis. Young plants should be protected with burlap during the first few winters in colder climates.

* photo taken on Feb 2009 @ U.S. National Arboretum, D.C.


* looking resonably good after the severe 2011 winter

* photos taken on October 17 2010 @ U.S. National Arboretum, D.C.





* photo taken on Aug 3 2014 @ National Zoo, Wash., DC

* photos taken on Feb 8 2014 @ U.S. National Arboretum, DC

* photo taken on Apr 17 2016 @ U.S. National Arboretum, DC

* photo taken on Nov 19 2016 @ London Town Gardens, Edgewater, MD

* photo taken on Aug 4 2021 @ U.S. National Arboretum, Washington, DC

* historic archive photos

* photo taken on May 27 2017 @ Meadowlark Botanical Gardens, Vienna, VA

* photo taken on Aug 24 2017 @ U.S. Botanic Garden, Wash. DC.

* photo taken on Sep 3 2017 @ U.S. National Arboretum, D.C.

* photo taken on July 21 2019 @ London Town Gardens, Edgewater, MD

* photos taken on Jan 9 2020 @ London Town Gardens, Edgewater, MD

* photos taken on Mar 26 2021 @ U.S. National Arboretum, Wash, D.C.

* photo taken on Aug 4 2021 @ U.S. National Arboretum, Washington, DC

* photo taken on Oct 23 2024 @ U.S. National Arboretum, Wash, DC

RELATED SPECIES

Nannorrhops ritchiana ( Mazari Palm )
An extremely rare, fast growing, multi-trunked fan palm that is native to mountainous areas of Pakistan, northern India and Afghanistan where it is endangered. Some records include: largest on record - 30 x 25 feet with a trunk diameter of 1 foot ( though usually seen as a shrub ).
The leathery, fan-shaped leaves, up to 4.5 feet across, are blue-green.
Old leaf bases persist and should be removed.
The white flowers are borne on branched spikes reaching above the crown that reach up to 5 feet in length.
The fruits are orange brown.
Hardy zones 6a to 9 in full sun on well drained soils in dry climates. It can tolerate as low as -14 F if dry during winter and can also easily tolerate 125 F during summer and actually requires hot summers. Very drought tolerant.
It thrives well in places such as California, Italy and southern France.

Mesquite

Prosopis

A genus of trees that are closely related to the Acacias. The seed pods are a food source that can be ground to flour. The pods can also be used to feed livestock. The flowers are used in the production of honey. The timber is aromatic and the smoke is used to BBQ meats.
They prefer full sun on deep well drained soil. Most Mesquite are extremely drought tolerant. Mesquites are very deep rooted and hate root disturbance. The wide spreading Mesquite roots have also been found as deep as 200 feet in their search of water. It is important to either plant from seed on permanent site or transplant while very small. Mesquite is very easy to grow in hot dry climates and have multi-use potential in many climates for reforestation as well as food and timber.
The massive network of roots on these trees can be used to prevent erosion, especially on stream banks. The roots of the Mesquite can also fix nitrogen thus improving the soil. Also never throw away old Mesquite pods, they can be used as a nitrogen rich fertilizer.
Young trees should be trained to a single trunk, thin out overcrowded thicket-like branches.
Propagation from seed is easily done if soaked in boiling water for 15 minutes then left in cooler water for 12 hours before sowing. It is also possible to speed up germination by nicking the seedcoat or scarifying it with acid before soaking it in water. The seed will not germinate until water penetrates through the hard seedcoat. In the wild, the seeds will often soften as they travel through the digestive systems of animals especially cows that eat the pods, explaining the increase of Mesquite in much of the southwestern U.S. Propagation can also be done from half hardened cuttings.
Pharmacology: Most species contain Tryptamine. Prosopis juliflora contains
5-HTP.

Interesting External Link on Mesquite trials
http://www.fao.org/docrep/006/AD321E/ad321e0a.htm

Video found on Youtube

* photo of unknown internet source

* historical archive photo

Prosopis affinis ( Algarobilla )
An attractive, massive trunked, broad-spreading, medium-size tree, reaching up to 65 feet, that is native to South America in southern Bolivia, Paraguay, southwest Brazil, Uruguay and northwest Argentina. It is threatened by habitat loss in the wild. A well grown tree resembles the Honey Locust in appearance. Some records include: 2 years - 7 x 10 feet; 4 years - 9.5 feet; 5 years - 11 feet; 6 years - 13 feet; 9 years - 16 feet.
The leaves are deciduous but persist very late in autumn or often until mid winter.
It is found in the wild on both upland sites and flood plains usually in open woodlands. Hardy zones 9 to 10, it thrives best where average annual rainfall is 24 to 48 inches per year, though it will tolerate the occasional drought. It is native to moisture climates than the other South American Mesquites.

Prosopis africana
Reaches a maximum size of 66 feet.
The pinnate leaves, up to 6 inches in length, are composed of leaflets up to 1.3 inches in length.

Prosopis alba ( Argentine Mesquite )
Also called White Mesquite. A fast growing, dense, medium size semi-evergreen tree with pendulous branch tips, that is native to Chile, Argentina, Bolivia and Peru. Some records include: fastest recorded growth rate - 7 feet; 2 years - 8 feet; 3 years - 14 feet; 8 years - 25 feet; largest on record - 60 x 100 feet with a trunk diameter of 5 feet.
It looks like a Gleditsia - Shademaster Locust with reddish bark and makes a stately shade tree in arid climates where it is adapted.
The compound leaves, up to 7 inches, are composed of 50 to 100 linear leaflets, up to 1 inches in length. The foliage is mid-green.
The creamy-white flowers are borne in racemes. They are followed by light yellow-brown seedpods, up to 10 inches in length.
The branch tips are sparsely armed with spines.
The bark is brown.
Hardy zones 8 to 10, tolerating as low as 10 F. Hardy in Tucson, AZ.
Very tolerant of heat, drought and salt.

'Colorado Thornless'
Thornless version.

Prosopis caldenia ( Argentine Mesquite )
A very deeply-rooted, large tree that is native to subtropical regions of Argentina. It can reach up to 100 feet in height with a trunk up to 6 feet in diameter. Trees as old as 1225 years are known.
Hardy zones 9b+

Prosopis chilensis ( Chilean Mesquite )
A rapid growing, dense, medium size evergreen tree native to Chile. Some records include: fastest recorded growth rate - 7 feet; 4 years - 11 x 10 feet; largest on record - 55 x 100 feet with a trunk diameter of 7.2 feet. It can live up to 260 years or more.
The pinnate leaves are up to 5 inches long. The leaflets are large for a Mesquite, up to 2 inches in length.
It is hardy zones 8b+ and tolerates temperatures anywhere between 10 F and 112 F. It does best with deep infrequent watering thus not making it a good lawn tree.
There is also a thornless variety available that makes an excellent street tree for dry climates.

* photos taken on Jan 2007 in Santiago, Chile



* photos taken on Aug 24 2017 @ U.S. Botanic Garden, Wash. DC.

Prosopis cineraria ( Arabian Mesquite )
Also called Prosopis spicigera or Shami. A fast growing, rounded, medium-sized tree native to the driest parts of Arabia, Iran, Afghanistan, Pakistan and India. It can Spread vigorously by root suckers. Root suckers have spread as much as 50 feet from original tree. Some records include: 1st year - 1 foot; 2 years - 1.9 feet; 11 years - 23 feet; largest on record - 60 feet in height with a trunk diameter of 4 feet. Arabian Mesquite has been recorded to have taproots as deep as 117 feet enabling them to survive extreme drought. It can live up to 400 years or more.
The pinnate leaves are composed of 7 to 14 leaflets up to 0.6 x 0.2 inches in size. The foliage is gray-green.
The creamy-yellow flowers are small.
Hardy zones 8b to 11 ( tolerating 16 F with no damage and surviving as low as 10 F ) in dry climates, it tolerates as little as 4 inches of rainfall per year. It thrives in parts of the U.S. southwest including Tucson, Arizona. Prefers soil PH from 6 to 9.8. It is tolerant of very salt and alkaline soil tolerant.

* photo of unknown internet source

Prosopis flexuosa
A spiny, small tree, reaching a maximum size of 40 feet, that is native to Chile, Argentina and dry valleys of the Bolivian Andes. It is considered a weed in parts of Argentina where it forms thickets on land used for livestock grazing. However a well grown tree also contributes valuable timber.
The lacy pinnate leaves are composed of linear leaflets. The foliage is mid-green.
The pods are up to 11.5 x 0.4 inches.
Hardy zones 8b to 10 ( tolerating 10 F ).

Prosopis glandulosa ( Honey Mesquite )
A spiny, crooked branched medium size tree native to the western and central U.S. ( from southern California to southwest Utah to central Nebraska; south into Mexico ). Some records include: 4 years - 20 feet; 20 years - 30 x 40 feet; largest on record - 70 x 90 feet with a trunk diameter of 5 feet; longest lived - 250 years.
An excellent shade tree in dry climates, especially in the central and western U.S. if trained and limbed up at a young age. It has invasive potential in Chile & Argentina ( use native South American Mesquites there ), South Africa and Australia and its use should be avoided there. Honey Mesquite is very deeply rooted, up to 60 feet in depth.
The bipinnate leaves are divided in to 2 or rarely 4 pinnae, up to 10 inches in length, are composed of up to 34 narrow elliptical leaflets, up to 1 x 0.25 inches.
The fragrant, fluffy, white to orange-yellow flowers are borne in slender spikes, up to 6 inches in length, during spring.
The nectar rich flowers attract honey bees.
They are followed by narrow, linear pods, up to 9 x 1 inches, that constrict between the seeds. The pods ripen during summer and can be harvested from mid summer to as late as September. They are sometimes produced so abundantly that they cover the ground beneath mature Mesquite trees. The pods are best immediately after they naturally fall off the tree and the quality varies from tree to tree. The pods are similar in flavor to that of a distant relative - the Carob tree ( Ceratonia siliqua ).
Mesquite pods can also be gathered before they ripened and be eaten raw or cooked as a vegetable. The entire pods ( incl. the seeds ) can also be dried and ground to a meal to make excellent flour. By throwing some pods on a barbecue you can add great flavor to cooked meats. Mesquite bread is very good and the flour can also be mixed with wheat flour to make other recipes including muffins. After grounding he pods to a meal, when you sift out the fibrous parts, do not throw them away. If you soak them in water to leach out the sugars - you can make a very good drink. Simply by boiling the pods for 20 minutes, you can make a good drink. Another drink can be made by mixing Mesquite flour with water.
Syrup every bit as good as Maple syrup can be made from boiling the pods.
The stems are armed with spines up to 2 inches in length. The bark is rich brown.
Old trees have very coarse bark with ragged ridges.
Mesquite wood is very hard but trees are often of too poor of form to make them commercially viable for lumber though they can be used for log cabin homes and rot resistant fence posts. Mesquite trees can be coppiced for fenceposts, poles and firewood which burns very hot.
Hardy zones 5 to 11. This tree is drought tolerant due to its deep roots.
It is also very heat tolerant as well as alkaline soil tolerant but shrubby on shallow soil. Mature Mesquite should be irrigated during extended severe drought only.
Honey Mesquite is not known to grow in the humid eastern U.S.

* photo of unknown internet source

* photos of unknown internet source

* historic archive photos

'Maverick'
Thornless

subsp 'torreyana'
Some records include: 3 years - 9 feet; 5 years - 12 feet; 6 years - 18 feet; 15 years - 22 feet; largest on record - 33 x 83 feet with a trunk diameter of 3 feet.
Has shorter leaves than regular Honey Mesquite.
Hardy at 15 F in Tucson

Prosopis juliflora
Description under construction. Some records include: largest on record - 50 feet with a trunk diameter of 3 feet. It can survive on as little as 6 inches of rainfall per year once it develops a deep taproot.

* photo taken by R.L. Hensel @ USDA-NRCS PLANTS Database

* historic archive photo

Prosopis laevigata ( Smooth Mesquite )
A small tree that is native to central Mexico. Some records include: 3 years - 5.5 feet; 4 years - 7 feet; 6 years - 11 feet; 10 years - 17 feet; 15 years - 20 feet.
The pinnate leaves are composed of many narrow oblong leaflets.
Hardy zones 8b to 10 ( no freeze damage at 15 F in Tucson, AZ ).

Prosopis nigra ( Black Mesquite )
A medium-sized evergreen tree native to Argentina and Paraguay in South America.
Some records include: fastest recorded growth rate - 4 feet; 3 years - 7 feet; 5 years - 10 feet; 9 years - 12 feet; 15 years - 15 feet; largest on record - 52 x 40 feet with a trunk diameter of 4 feet.
It is a stately shade tree in the arid climates where it is adapted.
The leaves, up to 8 inches in length, are composed of deep green leaflets.
The valuable wood is dark brown and very heavy. The wood is used to make furniture.
Hardy zones 8b to 10 ( no damage at 15 F ). It is tolerant of both severe drought and prolonged flooding, making it a great tree for river floodplains in desert regions.

* photo of unknown internet source


Prosopis pallida ( Algaroba )
A thorny, domed, medium-size tree native to northwest South America. Some records include: fastest recorded growth rate - 40 inches; 3 years - 4 feet; 21 years - trunk diameter of 15 inches; 70 years - 85 feet with a trunk diameter of 3.5 feet; largest on record - 90 x 85 feet with a trunk diameter of 6.6 feet. It has escaped into the wild and is now naturalized in Hawaii where it is invasive despite being a great shade tree in drier climates.
The pinnate leaves are composed of 8 to 18 pairs of narrow oblong leaflets.
The greenish-yellow flowers are borne in dense racemes during spring.
They are followed by linear pods up to 8 inches in length. The pods are edible and can be made into a sweet tasting drink.
Hardy zones 8 to 10 requiring between 10 and 50 inches of average yearly rainfall.

* photo of unknown internet source


Prosopis pubescens ( Screwbean Mesquite )
An extremely vigorous small tree native to bottomlands in the southwestern U.S. ( from southeastern California to western Texas; south to the border regions of Mexico ). Some records include: 2 years - 11 feet; 3 years - 15 feet; 5 years - 18 feet; 8 years - 25 feet; largest on record - 40 x 40 feet with a trunk diameter of 1.3 feet. An excellent shade tree for dry climates.
The bipinnate leaves, up to 8 inches long, are divided in to 2 or rarely 4 pinnae up to 2 inches, are composed of 5 to 9 pairs of tiny leaflets.
The fragrant, fluffy, greenish-white flowers are borne in slender spikes, up to 3 inches in length, durign spring.
They are followed by yellowish, narrow spiraled pods up to 2 inches in length.
The pods ripen during late summer but persist into late autumn. The pods, often eaten right off the tree, are even better tasting and sugar rich than those of Prosopis glandulosa.
The stems are armed with axilliary spines up to 2 inches in length. The bark is rich brown.
Hardy zone 7 to 9 tolerating as low as 0 F. Very heat and drought tolerant.
It is dying out in some parts of its native range due to the pumping of groundwater.

'Thornless'
Fast growing, semi-evergreen and thornless.

Prosopis tamaruga ( Atacama Mesquite )
A very fast growing medium size tree native to salt flats of the Atacama Desert in Chile where it is now endangered, it once formed vast forests here in the driest place on earth. The taproot that penetrates up to 50 feet in depth also makes this one of the worlds most drought hardy trees.
Some records include: fastest recorded growth rate - 7 feet; 3 years - 3.5 feet; 20 years - trunk diameter of 16 inches; largest on record - 65 x 60 feet with a trunk diameter of 5 feet; longest lived - 1000 years. The Atacama Mesquite is a very attractive tree that resembles the Honeylocust in appearance from a distance.
It has been planted in Spain and should be attempted in other dry regions such as Saudi Arabia and Africa's Sahara Desert.
The leaves are small, up to 1.5 inches in length.
The stems are armed with very sharp white spines.
No freeze damage noted at Tucson. Water every 10 days for the first year, every 30 days for the 2nd, cutting back after unless rapid growth is desired then it can be continued at once a month for the duration of the growing season, less while dormant.
This tree prefers soil PH 6.8 to 8.4 and responds very well to phosphorous fertilizer. Extremely salt tolerant.

Prosopis velutina ( Velvet Mesquite )
A fast growing, dense, deciduous, broad crowned tree native from southern California to eastern New Mexico; south to Sonora, Mexico. Some records include: fastest recorded growth rate - 4 feet; 2 years - 6 feet; 3 years - 10 feet; 5 years - 13 feet; 8 years - 16 feet; 12 years - 19 feet; largest on record - 60 x 60 feet with a trunk diameter of 5.5 feet.
A very attractive shade tree in arid climates where it is adapted and is commonly used in landscaping in Phoenix and Tucson, Arizona. It is among the most drought tolerant of all landscape shade trees but will sometimes drop its leaves during summer in cases of extreme drought ( a deep watering once of twice a month should prevent this and induce vigor ).
The pinnate leaves, up to 6 inches, are composed of 15 to 20 pairs of linear leaflets, up to 1 inch in length. The leaves close up at night. The foliage is deep green.
The fluffy golden-yellow flowers are borne in racemes up to 6 inches in length during summer.
They are followed by linear seed pods up to 12 inches in length, that are edible and sweet tasting.
The stems are viciously armed with yellowish spines up to 3 inches in length.
The bark on young trees is smooth and reddish-brown. On older trees it becomes shredded and gray-brown. The wood is popular for flavoring grilled meat.
Hardy zone 7 to 9 tolerating as low as 0 F. No freeze damage noted at Tucson.
Extremely drought tolerant, roots have been found as deep as 175 feet!
It is not known to grow in the humid eastern U.S.

* photo of unknown internet source

* historic archive photo