# Mesquite

Mesquite is a common name for some plants in the genera Neltuma and Strombocarpa, which contain over 50 species of spiny, deep-rooted leguminous shrubs and small trees. They are native to dry areas in the Americas. Until 2022, these genera were traditionally included in a broad view of the genus Prosopis, but that genus is now restricted to a few species native to the Old World.
Mesquites have extremely long roots to seek water from very far under ground. As they are legumes, mesquites are one of the few sources of fixed nitrogen in the desert habitat. The trees bloom from spring to summer. They often produce fruits known as "pods". Mesquites are able to grow up to 8 metres (26 ft) tall, depending on site and climate. They are deciduous and depending on location and rainfall have either deep or shallow roots. Mesquites are considered long-lived because of the low mortality rate after the dicotyledonous stage and juveniles are also able to survive in conditions with low light and drought. The Cahuilla indigenous people of western North America were known to eat the seeds of mesquite.

## History

Mesquites have been in North America since the Pliocene era and their wood has been dated to 3300 yr BP. They are thought to have evolved with megafauna in the New World. The loss of North American megafauna at the end of the Pleistocene era gave way to one theory of how mesquites were able to survive. One theory is that the loss of the megafauna allowed mesquites to use their fruit pods to attract other organisms to spread their seeds; then, with the introduction of livestock, they were able to spread into grasslands. Another is that mesquites had always been present in grasslands, but recurring fires had delayed plant and seed development before the emergence of livestock and grazing.

## Etymology

The English word mesquite is borrowed from the Spanish word mezquite, which in turn was borrowed from the Nāhuatl term mizquitl.

## Habitat

Mesquites grow as a small shrub in shallow soil or as tall as 15 metres (49 ft) in deep soil with adequate moisture, and forms a rounded canopy nearly as wide. They may have one or multiple trunks with a multitude of branches. They have bipinnate leaflets of a light green to blue hue that cast a light to deep shade, depending on the species. Spikes of flowers form in spring and summer that form a flat pod of beans 5–15 centimetres (2–6 in) long. Many species form thorns. When cut to the ground, the tree can often recover.

## Uses

Once the pod is dry, the whole pod is edible and can be ground into flour and made into bread.
Mesquite wood was a popular type of wood used by early Spaniards to build ships, but is now used most commonly for high-end rustic furniture and cabinets. Scraps and small pieces are used commonly as wood for cooking with smoke in Western, South Central American states.
Red-orange sap can be found on the branches of mesquite trees during the summer. This sap was used by those who lived in the desert for several medicinal treatments. The sap was used as a salve and spread on burns and cuts to speed up the healing process. Gargling a mixture of water and sap was used to soothe sore throats, and the same mixture was said to be able to cure upset stomachs.

## As an introduced and invasive species

Some mesquites are different from most invasive species because they are highly aggressive in both their native and introduced ranges. Their impacts on the invaded ecosystems include changes to hydrological, energy, and nutrient cycling, as well as consequences to biodiversity and primary production. Mesquite density and canopy cover influence the herbaceous layer and native shrubs and are factors in the changes to the ecosystem.

### In its native range

In the United States, mesquites have become the dominant woody plant on 38,000,000 hectares (94,000,000 acres) of semiarid grasslands. Although North America is in their native range, due to an imbalance within this ecosystem it has been able to spread rapidly. It is considered the most common and widely spread "pest" plant in Texas. An estimated 25% of Texas grasslands are infested and 16 million acres (6.5 million hectares) are so invaded that it is suppressing the majority of grass production. In Mexico and the US, the two most problematic species are honey mesquite (Neltuma glandulosa) and velvet mesquite (Neltuma velutina).

### As an introduced species

Honey and other mesquites have been introduced to parts of Africa, Asia, and Australia. Honey mesquite is considered by the World Conservation Union as one of the world's most problematic invasive species. Its spread into grasslands is mostly attributed to the introduction of domestic livestock, although other factors include climate change, overgrazing, and the reduction of fire frequency. The similar, related Prosopis species occur naturally in these areas, but these changes have resulted in these non-native relatives being able to successfully outcompete the native species, and they are now considered invasive species because they are able to take advantage of vulnerable ecosystems.
In Australia Neltuma spp. (N. pallida, N. glandulosa, N. velutina, and their hybrids with N. juliflora) are ranked nationally as one of the 20 most significant weeds. They now cover almost 1 million hectares (2.5 million acres) of land. Neltuma species were originally introduced to help with erosion because of their deep root systems.
Additionally N. laevigata was previously invasive in Australia, but has since been eradicated. The last known specimens of N. laevigata were eliminated in 2006, but given the possibility of lingering seeds in the soil seed bank, Biosecurity Queensland waited 15 years and declared Australia free of N. laevigata in 2021.
In India, mesquites had been introduced decades ago, but until recently, their effects had not been studied. This genus has been pushing out the Indian wild ass (Equus hemionus khur). This herbivorous mammal eats the pods of mesquites, which was one of the intended purposes of its introduction. Through digesting and excreting the seeds, the Indian wild asses are providing the habitat needed for germination. The 5,000 square kilometres (1,931 sq mi) Indian Wild Ass Sanctuary is experiencing mesquite invasion of roughly 1.95 square kilometres (0.75 sq mi) a year. By overtaking the land, the dense canopy cover of mesquite has made it so native vegetation cannot grow. It has also made watering holes inaccessible to the animals within this region. This lack of resources and range is forcing the endangered Indian wild ass into human landscapes and agriculture fields and locals are killing these asses to protect their crops.

### Control strategies

Controlling mesquite is a challenging task. One often-used method is mechanical control. This can be effective with high mortality rates if stems are cut at least 20 centimetres (8 in) underground. Another method is through the application of herbicides, done on an individual plant basis. Basal application is effective to mesquite of all sizes, while foliar application is best for plants smaller than 1.5 metres (5 ft). Another physical option for control is through fires. Some species of mesquite are fire-sensitive, while others are fire-tolerant. For those that are fire-sensitive, this method can be highly effective, but those that are fire-tolerant require hot and intense fires to be effective. In Australia, scientists are trying biological control methods. They have introduced multiple insects, but the most effective in causing high population level impact is the leaf-tying moth (Evippe spp.). The most recommended method for managing mesquites, both in native and introduced ranges, is by targeting large numbers of plants either through herbicide or physical removal. Also, research is being done on using satellite and aerial images to assess canopy cover and determine which ranges should be targeted.

## Species

* Neltuma alba (white mesquite)
* Neltuma chilensis (Chilean mesquite)
* Neltuma glandulosa (honey mesquite)
* Neltuma humilis
* Neltuma juliflora
* Neltuma laevigata (smooth mesquite)
* Neltuma nigra (black mesquite)
* Neltuma pallida
* Neltuma velutina (velvet mesquite)
* Strombocarpa pubescens (screwbean mesquite)
* Strombocarpa reptans (tornillo)
* Strombocarpa strombulifera (creeping mesquite)
The name 'mesquite' has also been misapplied in recent history to these Old World species, due to their previously considered congeneric affinity:
* Anonychium africanum (African "mesquite")
* Prosopis cineraria (Persian "mesquite")
* Prosopis farcta (Syrian "mesquite")

## Gallery

* Screwbean mesquite pods
* Screwbean mesquite flowers
* Honey mesquite, foliage with seedpods
* Velvet mesquite dried seeds
* Velvet mesquite tree
* Honey mesquite foliage