Size: Up to 30 feet (9.1 m) or more (35 feet - 10.7 m).
Growth Form: Desert Ironwood is a very slow growing desert tree or shrub with numerous sharp spines.
Leaves: Desert Ironwood has green or grayish-green leaves that are generally evergreen; the leaves are pinnatelycompound with 8 or more oval leaflets.
Flower Color: Desert Ironwood has showy, pale lavender or purple flowers with white; the flowers are pea-like and the fruit is a thick pod with 1 or more seeds.
Flowering Season: April or May and June.
Elevation: Usually below 2,500 feet (762 m) or so; below 4,200 feet (1,300 m) in California.
Habitat Preferences: Desert Ironwood is common in rocky and sandy soils and along dry washes in desert foothills.
Recorded Range: The Desert Ironwood is a relatively rare plant in the United States where it is native to Arizona and California. In Arizona it is found in the central and wester parts of the state and in California it is native to the southeast corner. It is also found throughout Baja California and central and northern Mexico.
North America & US County Distribution Map for Olneya tesota.
North America species range map for Desert Ironwood, Olneya tesota:
Click image for full size map.
Threatened/Endangered Information: In Arizona, pursuant to Title 3, Chapter 3, A.R.S. § 3903(B)(3), Olneya tesota is "Salvage Assessed, Harvest Restricted" (A permit from the Department of Agriculture is necessary to transport this species off private property).
Genus Information: In North America, USDA Plants Database lists 1monotypic species for Olneya. Worldwide, World Flora Online includes 1 accepted species names.
The genus Olneya was published in 1854 by Asa Gray, (1810-1888).
In the Southwestern United States: Arizona and California both have 1 species of Olneya, Nevada, New Mexico, Texas and Utah have 0 species. Data approximate, subject to revision.
Comments: This desert tree is a major species in the western Sonoran Desert community with other species such as Palo Verde, Saguaro, Ocotillo, Brittlebush, Creosote Bush, and Mesquite. Desert Ironwood is generally thought to be an indicator species of the Sonoran Desert in North America, Baja California and Mexico.
Ironwood Forest National Monument in south-central Arizona is named for Olneya tesota.
Desert Ironwood has a low tolerance for frost, its presence was also used as an "indicator" species in selecting sites for citrus orchards.
The type specimen for Olneya tesota was collected along the Gila River in Arizona, exact location unspecified.
Importance to Wildlife, Birds and Livestock
Desert Ironwood, Olneya tesota has attractive flowers, the flowers, their seeds and plants may be visited by hummingbirds and/or small mammals including rodents and large seed eating birds in search of food, nectar and protection through cover.
According to Bat Biologist Dr. Ginny Dalton, the Lesser Long-nosed Bat (Leptonycteris curasoae yerbabuena) is thought to migrate northward following the bloom of the Desert Ironwood tree. These bats have been documented to follow the bloom of other plant species as well. This bat ranges from the southern tip of Baja California north into Arizona and California and perhaps other southwestern states. The winter range is southward into Central America.
Beneficial Value to Butterflies, Honey Bees and Insects
Desert Ironwood, Olneya tesota has attractive flowers, the flowers and their plants may be visited or used by butterflies, moths, flies, honeybees, native bees and other insects in search of nectar, food or shelter and protection.
Etymology:
The genus “Olneya” (Ol'neya:) was named after Stephen Thayer Olney (1812-1878), a Rhode Island botanist and woolen manufacturer.
The species epithet “tesota” (teso'ta:) is a corruption of the Spanish tieso meaning "stiff or firm". Tesota is a southwest Native American name for this tree.
Ethnobotany
Ethno-Herbalist: Southern California Ethnobotany; Ethnobotany of Southern California Native Plants:Olneya tesota.
Ethnobotany - Native American Ethnobotany; University of Michigan - Dearborn
Desert Ironwood, Olneya tesota is used by southwestern United States indigenous peoples for such purposes described below.
Cahuilla Food, Staple; Roasted pods and seeds ground into flour.
Cahuilla Other, Fuel; Wood used for firewood.
Cahuilla Other, Tools; Wood used to make implements requiring extreme hardness: throwing sticks and clubs.
Cocopa Food, Porridge; Seeds roasted, ground and made into mush.
Mohave Food, Bread & Cake; Seeds parched, ground lightly, roasted and the meal made into thin loaves and baked.
