Prosopis L. is a genus of spiny trees and shrubs in the legume family Fabaceae, traditionally comprising around 40–44 species distributed across arid and semi-arid regions of every inhabited continent. The genus was described by Carl Linnaeus in 1767, with the generic name derived from the Greek word for "burdock," adapted into late Latin. A landmark 2022 genomic study found the historically broad genus to be polyphyletic, and the majority of species have since been reclassified into related genera — primarily Neltuma (for most American mesquites) and Anonychium and Strombocarpa. In its current sensu stricto circumscription, Prosopis contains just three accepted species: P. cineraria, P. farcta, and P. koelziana, all native to a band stretching from North Africa and the Middle East through Central Asia to the Indian subcontinent.
Plants in the genus are characteristically drought-tolerant, developing exceptionally deep tap roots capable of reaching groundwater far below the surface. They typically bear bipinnate leaves, bear clusters of small yellowish flowers, and produce elongated legume pods rich in sugars and proteins. The wood is hard, dense, and durable, prized across its native range for fuel, timber, and charcoal. Like other members of Fabaceae, Prosopis species fix atmospheric nitrogen through root nodules, making them valuable pioneers in degraded soils.
Several species historically placed in Prosopis — particularly Neltuma juliflora (formerly P. juliflora), N. glandulosa (honey mesquite), and N. velutina (velvet mesquite) — have become significant invasive weeds across Africa, Asia, and Australia, declared noxious over millions of square kilometres of arid and semi-arid land. Despite their ecological disruption, these plants also provide pods for fodder, wood for fuel, and shade in degraded landscapes, creating complex management challenges.
Etymology
The genus name Prosopis is of Greek origin, where it referred to "burdock" (Arctium). The word was carried into late Latin with the same sense before Linnaeus applied it to this unrelated legume genus in his 1767 Mantissa Plantarum. The motivation for the transfer is not documented in Linnaeus's original text; it may have been inspired by a superficial resemblance of the spiny branches or pods to burdock burrs.
Distribution
In its current sensu stricto circumscription, Prosopis is native to a continuous belt of arid and semi-arid territory spanning North Africa (Algeria, Libya, Tunisia, Egypt, Sinai), the Middle East (Lebanon-Syria, Palestine, Iraq, Saudi Arabia, Kuwait, Oman, Yemen, Gulf States), the Caucasus region, and Central Asia (Turkey, Iran, Afghanistan, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan), extending east to the Indian subcontinent (India, Pakistan). Prosopis cineraria also occurs across the Arabian Peninsula and has been introduced to Java. Prosopis farcta extends westward into northern Africa and northward into the Caucasus.
Under the broader historical circumscription, species referable to Neltuma and related genera occurred across the southwestern United States (Arizona, New Mexico), Mexico, Central America, and much of South America, with particular diversity in Argentina and Chile (P. alba, P. flexuosa, P. nigra, P. chilensis, P. caldenia). An African species, Prosopis africana, and various South American taxa were also long included. Several of these have been introduced — sometimes deliberately for fodder or shade — far outside these natural ranges, with substantial naturalized and invasive populations across sub-Saharan Africa, the Indian subcontinent, Australia, and the Middle East.
Ecology
Prosopis species (sensu lato) are ecological specialists of dryland environments. Their defining adaptation is an exceptionally deep tap root that can penetrate tens of metres to reach permanent groundwater, allowing survival in areas receiving as little as 150 mm of annual rainfall. This phreatophytic strategy also means plants can persist through multi-year droughts that eliminate competing vegetation.
The genus belongs to Fabaceae and fixes atmospheric nitrogen via root nodules, enriching otherwise nutrient-poor soils and facilitating succession of other plants. The pods, rich in sugars and proteins, are consumed by a wide range of mammals — including livestock and wildlife — which disperse seeds in dung, often at great distances from parent plants.
Where introduced outside their native ranges, several species (historically under Prosopis, now Neltuma) form dense, impenetrable thickets that exclude native vegetation, reduce biodiversity, alter soil moisture regimes, and degrade rangeland forage. Overgrazing amplifies invasion by eliminating grass competition and increasing bare soil for seedling establishment. Dense stands have been documented across the Sahel, Ethiopia, Kenya, Namibia, South Africa, India, and Australia.
Conservation
Several species historically classified in Prosopis — now primarily Neltuma juliflora, N. glandulosa, and N. pallida — rank among the world's most economically damaging invasive plants. The IUCN Global Invasive Species Database lists four species as major threats, with infestations declared across millions of square kilometres of arid and semi-arid lands in more than 50 countries. In the United States, Prosopis-group invasions caused an estimated $200–500 million per year in agricultural and rangeland losses in the mid-1980s. Affected countries include those throughout the Sahel, Sudan, Ethiopia, Kenya, Namibia, South Africa, India, and Australia.
Eradication is considered extremely difficult or impossible once established due to the deep root system, hard seed coat (which survives gut passage), and vigorous resprouting after cutting. Management strategies now emphasize utilization over removal — harvesting pods for livestock fodder, exploiting the wood for charcoal and timber, and converting dense stands to managed woodland — alongside preventing new seedling establishment through improved grazing management and early mechanical removal.
Cultural Uses
Across their native and naturalized ranges, Prosopis species (broadly construed) have been deeply integrated into human economies for millennia. The pods, which contain 20–30% sugars and significant protein, are ground into sweet flour used in flatbreads, porridges, and fermented beverages by indigenous peoples from the Sonoran Desert to the Atacama. In arid South Asian communities, the pods of Prosopis cineraria (khejri) form part of traditional Thar Desert cuisines.
The wood is hard, fine-grained, and extremely durable, prized for furniture, pestles and mortars, fence posts, and — most widely — charcoal and fuel. The bark, which may contain up to 18% tannins, is used in leather tanning, and the ash of burned pods yields potash for soap-making.
Traditional medicine records span multiple continents: leaf preparations are applied to headaches and toothaches; bark poultices treat skin diseases and fevers; root decoctions address digestive and urinary complaints. Modern phytochemical studies have investigated leaf and pod extracts for anti-inflammatory and antioxidant activity.
Prosopis cineraria holds particular cultural status in South Asia. It is the national tree of the United Arab Emirates and the state tree of Rajasthan, Western Uttar Pradesh, and Telangana in India. The tree features in Hindu religious observance — its leaves are exchanged as symbolic gold during the Dussehra festival — and it appears in the Mahabharata epic, underscoring a cultural relationship spanning several thousand years.
Taxonomy
Prosopis was described by Linnaeus in Mantissa Plantarum: 10 (1767) and has carried the authority Prosopis L. ever since. It was long treated as a broad genus of approximately 40–44 species arranged in five sections, placed in the subfamily Mimosoideae (now subsumed into the broadened Caesalpinioideae) of Fabaceae. Older heterotypic synonyms include Lagonychium M.Bieb. (1819), Dasiogyna Raf. (1832), and Pleuromenes Raf. (1838).
A 2022 phylogenomic study demonstrated that Prosopis as traditionally circumscribed is polyphyletic — that is, species grouped under the name do not all share a single most-recent common ancestor. As a result, the genus was restructured: the bulk of the New World species moved to the reinstated genus Neltuma, while smaller segregate genera Anonychium and Strombocarpa also received species. The residual Prosopis sensu stricto retains only three species (P. cineraria, P. farcta, and P. koelziana), all from the Old World (North Africa, Middle East, and South Asia), which form a coherent monophyletic group. Kew's POWO now recognises this restricted circumscription as the accepted treatment.
Propagation
Prosopis species are typically propagated from seed. The seed coat is hard and impermeable, requiring scarification (mechanical abrasion or brief immersion in concentrated sulfuric acid) or hot-water treatment to achieve reliable germination. Scarified seeds germinate rapidly under warm conditions (25–35°C). In naturalized and invasive contexts, seeds pass viably through the digestive tracts of livestock and wildlife, which is the primary mechanism of long-distance dispersal and a key challenge for control. Vegetative propagation by cuttings is possible but less commonly used; the deep tap root that develops early in seedling growth makes bare-root transplanting difficult. Container-grown seedlings are preferred for restoration or agroforestry plantings.
