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Prosopis pubescens - Benth.

Common Name Screw Bean
Family Fabaceae
USDA hardiness 7-10
Known Hazards None known
Habitats It is found in creek and river bottoms, sandy/gravely washes, or ravines at elevations from 100 - 1,300 metres[277 ]. It is found along streams, washes, floodplains, gullies, and in alkali sinks, oases, arroyos, and bajadas in the desert southwest[1050 ].
Range Southwestern N. America - California, Nevada, Utah, Arizona, New Mexico and Texas, south to northern Mexico (Baja Norte, Chihuahua, Coahuila, Sonora)
Edibility Rating    (2 of 5)
Other Uses    (3 of 5)
Weed Potential No
Medicinal Rating    (2 of 5)
Care (info)
Frost Hardy Well drained soil Moist Soil Full sun
Prosopis pubescens Screw Bean


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Prosopis pubescens Screw Bean
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Summary

Prosopis pubescens is a much-branched, spiny, deciduous shrub or a tree with a round, spreading crown; it can grow from 2 - 10 metres tall. The short bole can be 30 - 40cm in diameter[277 , 491 ]. The plant can be harvested from the wild for local use as a food, medicine and source of wood. Screwbean mesquite (Prosopis pubescens) produces flowers, pods, and beans that are edible after processing. The twisted pods are especially valuable, yielding flour, syrup, or broth, with a pure sweetness superior to other mesquite species. Gathering can be challenging due to thorns and frequent insect damage, but the pods remain edible even after years on the trees. USDA Zones 7–10; US native, not invasive.


Physical Characteristics

 icon of manicon of lolypop
Prosopis pubescens is a deciduous Tree growing to 6 m (19ft) by 6 m (19ft).
See above for USDA hardiness. It is hardy to UK zone 8 and is not frost tender. The flowers are pollinated by Bees, Insects. The plant is not self-fertile.
It can fix Nitrogen.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils and can grow in very alkaline and saline soils.
It cannot grow in the shade. It prefers dry or moist soil and can tolerate drought.

UK Hardiness Map US Hardiness Map

Synonyms

This name is a synonym of Strombocarpa pubescens. P. emoryi Torr. P. odorata auct. Strombocarpa odorata auct. Strombocarpa pubescens (Benth.) A.Gray.

Plant Habitats

Edible Uses

Seedpods - raw or cooked[277 ]. The immature pods can be harvested while still green and consumed raw as snacks[277 ]. Mature pods, collected in the late summer, were traditionally pounded toa fine flour using stone pestles. The meal was set out to dry and then stored for later use. This powder was mixed with other foods or made into small cakes[277 ]. The dark tan seedpod is tightly coiled into a spiral around 3 - 5cm long, and appears in pod clusters of 2 to 15. The seeds are very small, around 3mm long[277 ]. Screwbean mesquite (Prosopis pubescens) is one of the most distinctive mesquites of the American Southwest, easily recognized by its twisted, corkscrew-like pods. Like other mesquites, its flowers, pods, and seeds are edible after processing, but screwbean differs significantly in flavor, texture, and handling. The flowers, produced in dense yellow catkins during spring and summer, are edible fresh or cooked. They taste similar to alfalfa with a mild legume accent, and can be toasted, simmered into soups, or used to collect pollen. While not sweet, they are nutritious and easy to gather in quantity. The immature pods are green, fibrous, and mildly flavored, with some bitterness. They can be eaten raw or cooked, though their food value is limited compared to that of mature pods. The mature screwbean pods are highly important. Twisted into tight spirals, they enclose 10–30 tan beans immersed in sticky, sweet pulp. Unlike other mesquites, the bean casings of screwbean split easily when pounded, making them far easier to process. Several preparation methods were traditional: 1. Pounded and boiled pods yield a sweet, wholesome gruel. 2. Pounded, sifted, and ground pods produce mesquite flour, though some sugars are lost with the fibrous debris. 3. Boiled and filtered pods make a rich, sweet broth that can be further reduced into mesquite syrup.The flavor of screwbean pods is excellent—sweet and nutty, without the hay-like or alfalfa overtones of other mesquites. Pods can remain on the trees for years and still retain their sweetness. The beans themselves are edible once thoroughly boiled, though they are best used as part of whole-pod processing rather than eaten alone [2-3].

References   More on Edible Uses

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.


The fibrous bark can be made into a dressing for wounds[277 ]. A decoction of the bark was used as a wash on fresh wounds then the dried and powdered bark was applied to the wound over the next few days[277 ]. A tea made from the roots has been used to treat problems with the menstrual cycle[277 ]. A gummy exudate sometimes found on the bark can be soaked in water and the resulting liquid used as eyewash[277 ].

References   More on Medicinal Uses

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Other Uses

Agroforestry Uses: The pollen is said to be toxic to honeybees[277 ]. This is one of several mesquite species that make excellent bee forage, the bees harvesting both nectar and pollen. The flowers are also a source of nectar for butterflies[1050 ]. Nitrogen Fixer. Other Uses: The wood is used traditionally for construction, posts etc[277 ]. The wood is an important fuel in its native range[491 ]. The root wood makes a good fuel for cooking[277 ].

Special Uses

References   More on Other Uses

Cultivation details

It is a shrub or tree and grows primarily in the desert or dry shrubland biome. Requires a sunny position in well-drained soil. Plants can succeed in a wide range of soil conditions, from light sands to heavy clays[1050 ]. Tolerant of moderately saline soils and also of alkaline conditions up to a pH of at least 10.6[1050 ]. Plants are very drought tolerant; so long as their roots can reach the groundwater, they can also withstand up to 3 months of soil inundation [1050 ]. Plants resprout from the base if they are cut down[277 ]. Although top-killed by severe forest fires, the plant will usually resprout from the base[1050 ]. This species has a symbiotic relationship with certain soil bacteria; these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant, but some can also be used by other plants growing nearby[1050 ]. USDA Hardiness Zones: Typically 7–10, adapted to hot, arid river valleys of the Southwest. Weed/Invasiveness: Native to the region; not generally invasive, though it forms dense thickets along rivers and can be thorny and difficult to manage.

References   Carbon Farming Information and Carbon Sequestration Information

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Plant Propagation

Like many species within the family Fabaceae, once they have ripened and dried the seeds of this species may benefit from scarification before sowing in order to speed up and improve germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing[K ].

Other Names

If available other names are mentioned here

Screwbean Mesquite

Native Range

Native to: Arizona, California, Mexico Northeast, Mexico Northwest, Nevada, New Mexico, Texas, Utah. Introduced into: Cape Provinces, India.

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it's worth checking.

Native to the region; not generally invasive, though it forms dense thickets along rivers and can be thorny and difficult to manage.

Conservation Status

IUCN Red List of Threatened Plants Status : Least Concern.

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Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.

 

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Author

Benth.

Botanical References

Links / References

For a list of references used on this page please go here
A special thanks to Ken Fern for some of the information used on this page.

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Subject : Prosopis pubescens  
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