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Scientific: Prosopis alba (Synonym: Neltuma alba)
Common: Argentine mesquite, algarrobo blanco, algarrobo panta
Family: Fabaceae (Leguminosae)
Origin: Arid and subtropical regions of South America; Bolivia, Peru, Argentina, and Paraguay. It has naturalized in Hawaii.

Taxonomic confusion: The genus Prosopis is under going a seismic taxonomic reorganization.

Pronounciation: Pro-SO-pis AL-ba

Hardiness zones
Sunset
12-13, just recently grown in nurseries in southern California
USDA 9-10 (arid and semi arid regions only)

Landscape Use: Argentine mesquite is a large summer shade tree for oasis and xeric landscapes. This is not a lawn or street tree, nor is it a mesic tree or a tree for small urban spaces!

Form & Character: Large, upright and spreading, asymmetrical form, nearly always twisting, contorted and mis-shapen when young with the potential of becoming picturesque with age (so long as it has been properly trained).

Growth Habit: Woody, evergreen to deciduous perennial tree, fast growing, irregularly spreading and randomly branched, 30- to 40-feet tall with a spread of 80- to 100-feet, trunk rough chocolate brown w/ age, growth begins each year in May and continues through November.

Foliage/Texture: Bipinnate compound leaves to 4-inches long. Young trees often have only two pinna; however, as tree specimens mature they will grow foliage with four pinna. Leaflets, in numerous pairs, are generally only 1/2-inch long. Leaves with stipular spines present or absent; when present can grow sometimes to 2-inches long and are dangerous; medium fine texture.

Important note: Foliage of Prosopis alba is generally slightly smaller than Prosopis chilensis.

Flowers & Fruits: Flowers are greenish yellow catkins in spring, relatively inconspicuous because of color; fruits are 3- to 5-inch long twisted, beige pods, ripen in July and fall off the tree all at once around July 15th, indehiscent, edible.

Seasonal Color: None

Temperature: Fully heat tolerant, cold hardy to 15oF.

Light: Full sun

Soil: Tolerant

Watering: Drip irrigation during the first year after planting into the landscape, thereafter little to no supplemental irrigation is needed.

Pruning: Argentine mesquite will require vigorous training and corrective pruning when young to establish an upright and symmetrical crown architecture with well-spaced scaffold branches.

Propagation: Seed is the historically common method; however, commercial nurseries are now propagating asexually by cuttings, air layering, and grafting. Selection and asexual propagation of superior clones (thornless, evergreen habit, symmetrical branch habit) offers the best future for this tree in local urban landscapes.

Disease and Pests: Aphids on new growth in spring (it's raining honey dew on my car!). Bacterial wetwood is nearly ubiquitious on all urban trees. Also, Texas root rot if soils are excessively wet during summer.

Additional comments: South American mesquite trees in Phoenix landscapes are hybrids of Prospis alba and Prosopis chilensis. South American hybrid mesquites make excellent summer shade trees if cultured correctly. Always select thornless variants that are asexually propagated.

Some superior locally cultivated selections include:

In general, South American mesquite trees produce MUCH litter throughout the year, such as the obligatory undercanopy mangled carpet of seed pods in July. Young container-grown hybrid mesquite trees can be prone to blow over during summer monsoon storms if they have girdled roots (root deformation caused by growth in nursery containers), are heavily drip irrigated with drip emitters positioned close to tree trunk, or if they are planted in turf as a lawn tree. Young trees should be staked securely and trained religiously to develop a straight central trunk and a strong schaffold branch architecture. Like Chilean mesquite, Argentine mesquite produces frequent crossed branches and grows weakly attached epicormic shoots around pruning wounds. Much genetic variation and local hybridization with Prosopis chilensis makes identification using only phenotypic characters difficult. The sapwood of Argentine mesquite is light yellow, while the heartwood is rich reddish brown changing to dark brown. In Phoenix, South American mesquite hybrids will grow large lateral roots that will remain near the surface of urban landscapes because of superficial landscape irrigation and shallow desert soil profiles.

The food and sticks narrative: Mesquite has been broadly used by native Americans for many centuries as a staple agricultural and industrial crop. The fruit pods have been used to make flour, no-bake bread, a thick Mexican beverage called "atole", candy, syrup, sourdough waffles, or even beer. Today, city dwellers such as aging hippies, local foods advocates, desert survivalists, 'idealistic' millenials, and 'triggered' zoomers have all put down their keyboards and smart phones to 'venture out' into nature and 'discover' this useful mesquite tree. For the rest of us, mesquite from our urban forests are best known as a dense-wooded tree used for furniture making, wood fires, or grilling fine meats on the barbeque!