# Olneya

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***Olneya tesota*** is a [perennial](/source/Perennial_plant) flowering [tree](/source/Tree) of the family [Fabaceae](/source/Fabaceae), legumes (peas, beans, etc.), which is commonly known as **[ironwood](/source/Ironwood)**, **desert ironwood**, or **palo fierro** in Spanish. It is the only species in the [monotypic genus](/source/Monotypic_genus) ***Olneya***. This tree is part of the western [Sonoran Desert](/source/Sonoran_Desert) in Mexico and United States.

## Description

The desert ironwood grows as a [bush](/source/Shrub) or [tree](/source/Tree), reaching heights of about 10 metres (33 feet) and average trunk diameters of about 60 centimetres (24 inches). 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](/source/Evergreen), but can lose its [leaves](/source/Leaves) if temperatures fall below 2 °C (36 °F). In continual drought conditions the leaves will be lost.

The leaves are bluish-green and pinnately compound. They are arranged on a [petiole](/source/Petiole_(botany)), 15 cm (6 in) long, with 6–9 leaflets (or variously up to 15, with seven opposite and one terminal), each measuring 0.7 to 2.5 cm (0.28 to 0.98 in). At the base of each pinnate leaf petiole grow two thorns, each about 1 cm (0.39 in) long.[citation needed]

Bloom time occurs in late April/May to June. Flowers are of five unequal petals, in colors of medium purple, magenta-red, or white to pale pink. Seedpods are 5–8 cm (2.0–3.0 in) long and light reddish brown when seedpods have ripened.[citation needed]

Two other species, *[Parkinsonia florida](/source/Parkinsonia_florida)* (blue palo verde) and *[Acacia constricta](/source/Acacia_constricta)* (catclaw acacia), have similar light red/brownish seedpods. Catclaw acacia's seedpods are shorter and J-shaped.[citation needed]

## Taxonomy

The genus name of *Olneya* is in honour of [Stephen Thayer Olney](/source/Stephen_Thayer_Olney) (1812–1878), who was an American manufacturer and [botanist](/source/Botanist) with expertise in the genus *[Carex](/source/Carex)*.[2][3]

The genus was [circumscribed](/source/Circumscription_(taxonomy)) by [Asa Gray](/source/Asa_Gray) in Pl. Nov. Thurb. page 328 in 1854.[4]

## Distribution and habitat

The species is native to the [Southwestern United States](/source/Southwestern_United_States) and extreme northwestern Mexico in the [Baja California Peninsula](/source/Baja_California_Peninsula) and the [Sonoran Desert](/source/Sonoran_Desert). Within Mexico its range includes the states of [Baja California Sur](/source/Baja_California_Sur) and [Baja California](/source/Baja_California), on the [Gulf of California](/source/Gulf_of_California) side east of the cordillera ranges, and [Sonora](/source/Sonora) state west of the [Sierra Madre Occidental](/source/Sierra_Madre_Occidental) cordillera, in the south approaching the northern border of northern [Sinaloa](/source/Sinaloa) state. In the Southwestern US its range includes the [Colorado Desert](/source/Colorado_Desert) of southeast [Southern California](/source/Southern_California), a part of the Sonoran Desert, and western and southern [Arizona](/source/Arizona).[4] *Olneya* does not range into the higher-elevation, colder, southeast of Arizona's Sonoran Desert region, nor into the [sky islands](/source/Sky_island) of the [Madrean Sky Islands](/source/Madrean_Sky_Islands) region.

## Ecology

The pleasant-tasting sap is consumed by bees and hummingbirds. The [silky-flycatcher](/source/Silky-flycatcher) or *[phainopepla](/source/Phainopepla)* pose a problem, for when they consume mistletoe berries and excrete them in the cracks of *Olneya tesota*, the mistletoe will parasitize its host.[5]

### An indicator species

*Olneya tesota* is an [indicator species](/source/Indicator_species) of the Sonoran Desert region.[6] The Sonoran Desert has at least one other species with an identical north–south, and east–west range. The seasonally migrating [lesser long-nosed bat](/source/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.[7] *O. tesota* associates such as the [saguaro cactus](/source/Saguaro_cactus) are major nectar and fruit sources for this bat.[8][9]

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.[citation needed]

The winter and permanent range of the bat extend into the northern countries of [Central America](/source/Central_America).[citation needed]

## Uses

The seeds can be eaten by first being roasted.[10]

*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](/source/Mexican_ironwood_carvings) as well as [knife](/source/Knife) handles.

## Conservation

*Olneya tesota* was classified as [Near Threatened](/source/Near_Threatened) by the [International Union for Conservation of Nature](/source/International_Union_for_Conservation_of_Nature) (IUCN) in 2018.[11] It is threatened by felling for wood carving and fuel, urbanization causing [habitat loss](/source/Habitat_loss) and invasive species such as [buffelgrass](/source/Buffelgrass), which contributes to frequent and intense wildfires in areas where it is established.[11][12]

## Culture

[Ironwood Forest National Monument](/source/Ironwood_Forest_National_Monument) in south-central Arizona is named for *O. tesota*.

## See also

- [Mexican ironwood carvings](/source/Mexican_ironwood_carvings)

## References

1. Quattrocchi, Umberto (2016). *CRC world dictionary of medicinal and poisonous plants : common names, scientific names, eponyms, synonyms, and etymology*. CRC Press. ISBN 9781482250640.

1. Burkhardt, Lotte (2022). [*Eine Enzyklopädie zu eponymischen Pflanzennamen*](https://doi.org/10.3372/epolist2022) [Encyclopedia of eponymic plant names] (pdf) (in German). Berlin: Botanic Garden and Botanical Museum, Freie Universität Berlin. [doi:10.3372/epolist2022](https://doi.org/10.3372/epolist2022). ISBN 978-3-946292-41-8. Retrieved January 27, 2022.

1. ["*Olneya* A.Gray | Plants of the World Online | Kew Science"](https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:327686-2). *Plants of the World Online*. Retrieved 1 September 2022.

1. Peattie, Donald Culross (1953). *A Natural History of Western Trees*. New York: [Bonanza Books](/source/Bonanza_Books). p. 587.

1. Little Jr., Elbert L. (1976). ["Map 103, *Olneya tesota*"](https://archive.org/details/atlasofunitedsta1314litt/page/n173/mode/1up). *Atlas of United States Trees*. Vol. 3 (Minor Western Hardwoods). US Government Printing Office. LCCN 79-653298. [OCLC 4053799](https://www.worldcat.org/oclc/4053799)

1. Dalton, Ginny (2008). ["Lesser Long-nosed Bats: Why Do They Migrate?"](https://web.archive.org/web/20080705135436/http://www.learner.org/jnorth/tm/spring/Bats_LeptoRangeMap.html). *Journey North: Signs of Spring*. Annenberg Media. Archived from [the original](http://www.learner.org/jnorth/tm/spring/Bats_LeptoRangeMap.html) on 5 July 2008.

1. Krebbs, Karen & Petryszyn, Yar (13 January 2021). ["Lesser Long-Nosed Bat"](https://www.desertmuseum.org/programs/ifnm_bat.php). *Biological Survey of Ironwood Forest National Monument*. Arizona-Sonora Desert Museum. Retrieved 4 January 2026.

1. ["Food Sources for Lesser Long-Nosed Bats At Selected Portions of Their Range (by Month)"](https://web.archive.org/web/20081011073842/http://www.learner.org/jnorth/tm/spring/Bat_BloomingCalendar.html). *Journey North: Signs of Spring*. Annenberg Media. 2008. Archived from [the original](http://www.learner.org/jnorth/tm/spring/Bat_BloomingCalendar.html) on 11 October 2008.

1. Little, Elbert L. (1994 [1980]). *The Audubon Society Field Guide to North American Trees: Western Region*. Chanticleer Press ed. Knopf. p. 498. ISBN 0394507614.

1. Barstow, M. (2018). "*Olneya tesota*". [doi:10.2305/IUCN.UK.2018-2.RLTS.T62026716A62026718.en](https://doi.org/10.2305/IUCN.UK.2018-2.RLTS.T62026716A62026718.en). Retrieved 4 January 2026.

1. Hubbard, Tani et al. (13 January 2021). ["Natural History of the Desert Ironwood Tree (*Olneya tesota*)"](https://www.desertmuseum.org/programs/ifnm_ironwoodtree.php). *Biological Survey of Ironwood Forest National Monument*. Dimmitt, Mark A. & Van Devender, Thomas R. et al. (eds.). Arizona-Sonora Desert Museum. Retrieved 4 January 2026.

## External links

- [Calflora Database: *Olneya tesota* (desert ironwood, ironwood)](http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=5914)
- [USDA Plants Profile of *Olneya tesota* (desert ironwood)](https://plants.usda.gov/java/profile?symbol=OLTE)
- [UC Photos gallery – *Olneya tesota*](http://calphotos.berkeley.edu/cgi/img_query?query_src=photos_index&where-taxon=Olneya+tesota)

- Lesser Long-nosed Bat Ranges – equal to *Olneya tesota*:

- - [Journey of the Nectar Bats](http://findarticles.com/p/articles/mi_m1169/is_/ai_76028890) - [Learner.org: Map of Lesser Long-nosed Bat range](http://www.learner.org/jnorth/images/graphics/a-b/bat-Sonoran-regions.jpg) [Archived](https://web.archive.org/web/20120306023756/http://www.learner.org/jnorth/images/graphics/a-b/bat-Sonoran-regions.jpg) 2012-03-06 at the Wayback Machine - [Learner.org: "Signs of Spring"](http://www.learner.org/jnorth/tm/spring/Bats_LeptoRangeMap.html) [Archived](https://web.archive.org/web/20080705135436/http://www.learner.org/jnorth/tm/spring/Bats_LeptoRangeMap.html) 2008-07-05 at the Wayback Machine – *article*.

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Adapted from the Wikipedia article [Olneya](https://en.wikipedia.org/wiki/Olneya) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Olneya?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.