''Olneya tesota'' is a

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wid ...

flowering

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

of the family Fabaceae, legumes (peas, beans, etc.), which is commonly known as

ironwood Ironwood is a common name for many woods or plants that have a reputation for hardness, or specifically a wood density that is heavier than water (approximately 1000 kg/m3, or 62 pounds per cubic foot), although usage of the name ironwood in E ...

, desert ironwood, or palo fierro in Spanish. It is the only species in the

monotypic genus In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

''Olneya''. This tree is part of the western

Sonoran Desert The Sonoran Desert ( es, Desierto de Sonora) is a desert in North America and ecoregion that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the southwestern United States (in Ariz ...

complex in the Southwestern United States.

Description

The desert ironwood grows as a bush or

, reaching heights of about and average trunk diameters of about . Exceptionally, in larger protected washes it can reach greater height and a more massive trunk. In younger trees, the bark is gray, shiny, and smooth; in older trees the bark is broken open. The tree is

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...

, but can lose its leaves if temperatures fall below . In continual drought conditions the leaves will be lost. The leaves are bluish-green and pinnately compound. They are arranged on a petiole, long, with 6–9 leaflets (or variously up to 15, with 7 opposite and one terminal), each measuring . At the base of each pinnate leaf petiole grow two thorns, each about long. Bloom time occurs in late April/May to June. Flowers are of 5 unequal petals, in colors of medium purple, magenta-red, or white to pale pink. Seedpods are long and light reddish brown when seedpods have ripened. Two other species, ''

Parkinsonia florida ''Parkinsonia florida'', the blue palo verde ( syn. ''Cercidium floridum''), is a species of palo verde native to the Sonoran Deserts in the Southwestern United States and Northwestern Mexico.

'' (blue palo verde) and '' Acacia constricta'' (catclaw acacia), have similar light red/brownish seedpods. Catclaw acacia's seedpods are shorter and .

Taxonomy

The genus name of ''Olneya'' is in honour of

Stephen Thayer Olney Stephen Thayer Olney (February 15, 1812 – July 27, 1878) was an American manufacturer and botanist with expertise in the genus ''Carex''. The monotypic plant genus ''Olneya'' ('' Olneya tesota'', desert ironwood) was named in his honor by his f ...

(1812–1878), who was an American manufacturer and botanist with expertise in the genus ''

Carex ''Carex'' is a vast genus of more than 2,000 species of grass-like plants in the family Cyperaceae, commonly known as sedges (or seg, in older books). Other members of the family Cyperaceae are also called sedges, however those of genus ''Carex'' ...

''. The genus was circumscribed by Asa Gray in Pl. Nov. Thurb. page 328 in 1854.

Distribution and habitat

The species is native to the Southwestern United States and extreme northwestern Mexico in the Baja California Peninsula and the

. Within Mexico its range includes the states of Baja California Sur and

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

, on the

Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...

side east of the cordillera ranges, and Sonora state west of the

Sierra Madre Occidental The Sierra Madre Occidental is a major mountain range system of the North American Cordillera, that runs northwest–southeast through northwestern and western Mexico, and along the Gulf of California. The Sierra Madre is part of the American ...

cordillera, in the south approaching the northern border of northern Sinaloa state. In the Southwestern US its range includes the Colorado Desert of southeast

Southern California Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most populous urban a ...

, a part of the Sonoran Desert, and western and southern

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

. ''Olneya'' does not range into the higher-elevation, colder, southeast of Arizona's Sonoran Desert region, nor into the

sky island Sky islands are isolated mountains surrounded by radically different lowland environments. The term originally referred to those found on the Mexican Plateau, and has extended to similarly isolated high-elevation forests. The isolation has s ...

s of the

Madrean Sky Islands The Madrean Sky Islands are enclaves of Madrean pine–oak woodlands, found at higher elevations in a complex of small mountain ranges in southern and southeastern Arizona, southwestern New Mexico, and northwestern Mexico. The sky islands are s ...

region.

Ecology

The pleasant-tasting sap is consumed by bees and hummingbirds. The

silky-flycatcher The silky-flycatchers are a small family, Ptiliogonatidae, of passerine birds. The family contains only four species in three genera. They were formerly lumped with waxwings and hypocolius in the family Bombycillidae, and they are listed in tha ...

or ''

phainopepla The phainopepla or northern phainopepla (''Phainopepla nitens'') is the most northerly representative of the mainly tropical Central American family Ptiliogonatidae, the silky flycatchers. Its name is from the Greek meaning "shining robe" in ref ...

'' pose a problem, for when they consume mistletoe berries and excrete them in the cracks of ''Olneya tesota'', the mistletoe will parasitize its host.

An indicator species

''Olneya tesota'' is an indicator species of the Sonoran Desert region. The Sonoran Desert has one other species with the identical north–south, and east–west range. The seasonally migrating lesser long-nosed bat follows the bloom season of various species from south to north and extends into the same regions of the Sonoran Desert as ''Olneya''. The bat ranges from southern Baja California del Sur and north into the Southwestern US. In the north, both species define the Colorado Desert sub-region of the Sonoran Desert surrounding the northern end of the Gulf of California; further south in the Baja Peninsula the sub-division is defined as the Vizcaino Desert. The winter and permanent range of the bat extend into the northern countries of

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

Uses

The seeds can be eaten by first being roasted. ''Olneya'' ironwood is very hard and heavy. Its density is greater than water and thus sinks; it does not float downstream in washes and must be moved by current motion. Due to its considerable hardness, processing desert ironwood is difficult. Final treatment of the wood with solutions can also be difficult because of its high density. As a result, mass processing of this wood is difficult, and most of its commercial usages are artisanal, such as durable wooden sculptures as well as

knife A knife ( : knives; from Old Norse 'knife, dirk') is a tool or weapon with a cutting edge or blade, usually attached to a handle or hilt. One of the earliest tools used by humanity, knives appeared at least 2.5 million years ago, as evidence ...

handles.

Culture

Ironwood Forest National Monument in south-central Arizona is named for ''O. tesota''.

References

External links

Calflora Database: ''Olneya tesota'' (desert ironwood, ironwood)

USDA Plants Profile of ''Olneya tesota'' (desert ironwood)

UC Photos gallery – ''Olneya tesota''
* Lesser Long-nosed Bat Ranges – equal to ''Olneya tesota'':
Journey of the Nectar Bats

Learner.org: Map of Lesser Long-nosed Bat range

– ''article''. {{Taxonbar, from=Q675377 Robinieae Monotypic Fabaceae genera Trees of the Southwestern United States Trees of Northwestern Mexico Flora of the California desert regions Flora of the Sonoran Deserts Natural history of the Colorado Desert