(Photograph = Prosopis juliflora, Poncho Borquez)
Prosopis juliflora, A Conflict of Interest Desert Tree
(Photograph = Prosopis juliflora, Poncho Borquez)
Introduction
Prosopis juliflora is a large shrub or small tree in the family Fabaceae, a mesquite. It is native to Mexico, South America, and the Caribbean. It has become established as an invasive weed in Africa, Asia, Australia, and elsewhere.
The Details
P. juliflora has carried an impressive number of scientific names and has been treated in Acacia as well as Mimosa. It now seems settled under its current name. It is a member of the Leguminosae (bean family).
Prosopis juliflora thrives in sandy, rocky, poor, and saline soils within an altitude range of roughly 300–1,900 m above sea level. With deep taproots, it can access subsurface water; in Arizona, one tree had roots descending to about 175 ft.
P. juliflora can grow to 30 ft or taller, but it is often a small tree or large shrub. The green, bean-like pods are 8–15 inches long and may contain up to 30 seeds. Seeds are spread by cattle and other animals that consume the pods.
P. juliflora is used for forage, wood, and environmental management. It is important in certain tropical woodlands for wildlife and can serve as a nurse tree for some columnar cacti. At the same time, it is considered a noxious invader in Ethiopia, Hawai‘i, Sri Lanka, Jamaica, the Middle East, India, Nigeria, Sudan, Somalia, Senegal, and southern Africa. P. juliflora is, therefore, a conflict-of-interest species: clearly useful but also clearly a noxious weed.
A Note
Prosopis species are salt- and drought-tolerant. With deep roots, they tolerate both dry and waterlogged soils. Seed production is prolific. Trees rapidly form dense, thorny thickets that reduce biodiversity. Invaded grasslands are converted to woodland and pasture is lost; reduced grass cover under canopies may also promote soil erosion. Water impacts can be substantial, and the tree resprouts readily after damage.
Additional Reading: Prosopis juliflora
