Velvet Mesquite
Prosopis velutina
Description: P. velutina is a thorny, deciduous tree or shrub. Mature trees have dark-brown to blackish trunks. Stout thorns occur on young branches.1 The leaves are compound, with green, short, hairy, and closely spaced leaflets.2 The largest trees are generally those found along water courses or floodplains where the roots have access to water. These trees may grow up to fifty feet tall and form open, park-like 'bosques,' or mesquite woodlands.1 The mesquite found in the desert grasslands tends to be shrub-like, growing only to about four feet tall. In spring, the mesquite produces large inflorescences of yellow flowers which are pollinated by bees.1 The legume-type fruit is flattened, three to five inches long, and may occur in singly or in clusters.
Habitat: Velvet mesquite occurs in low-elevation vegetation types, including paloverde bursage, cacti, desert grasslands, oak woodlands, and pinyon-juniper woodlands.1 Along major water courses and their tributaries, the velvet mesquite can form bosques. Velvet mesquite bosques generally occur in soils ten to forty-five feet above the water table.3
Range: The velvet mesquite ranges from central and southern Arizona, extreme southwestern New Mexico, and adjacent northern Mexico. The mesquite bosques have been in decline due to groundwater pumping and tamarisk invasion; the shrubby form of mesquite has been spreading throughout the grasslands of southeastern Arizona. 2
The Velvet Mesquite in Pima County: Ripe mesquite fruit provides a valuable food source for livestock and wildlife.1 Mesquite wood is used for firewood and charcoal. Bosques provide cover and habitat for many types of animals, including the collared peccary, mule deer, and many species of rodents. The white-wing dove, as well as other species of birds, depend on mesquite bosques for breeding and roosting.5 The tree also provides excellent habitat for many species of lizards.1
During the settlement of southern Arizona, bosques were cleared for firewood, lumber, and agricultural use.1 Currently, bosque destruction occurs for fuelwood cutting, agriculture, housing developments, and the lowering of the water table.1 Entire velvet mesquite bosques have been destroyed due to groundwater pumping for agricultural use.1 To maintain healthy bosques, the water table must not drop below twenty-six feet.4 Bosque destruction results in the decline of nesting bird species and other animals that depend on the mesquite for shelter and as a food source.1 Historically, mesquite bosques and other river bottom forests supported the greatest number of cactus ferruginous pygmy owl (Glaucidium brasilianum cactorum).5 The large trees provided cavities for nesting and roosting, and their location near a water source provided a high diversity of prey. Merriam's mouse (Peromyscus merriami) has declined greatly due the destruction of mesquite bosques.
References
1 Prosopis velutina: Distribution and occurrence. 11/1/99 Website: www.huntana.com/feis/plants/tree/provel/
2 Pinkava, Donald J. June 1999. "Species Profile: Mesquite." Arizona Riparian Council. Volume 12, Number 2. pp. 9-10.
3 Arizona Riparian Protection Program Legislative Report. July 1994. Arizona Department of Water Resources. pp.103, 138.
4 Phillips, Allan, Joe Marshall, Gale Monson. 1983. Birds of Arizona. The University of Arizona Press. pp. 42.
5 Fish and Wildlife Service. "Endangered and threatened wildlife and plants; Determination of Endangered Status for the Cactus Ferruginous Pygmy Owl in Arizona." Federal Register. March 10, 1997. Volume 62, Number 46.
11/1/99 Website: www.huntana.com/feis/plants/tree/provel/
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