a sonoran desert icon
low water (top zone)
HARDY TO 20º F
typically reaches 30' x 30', some have grown to nearly 50'
purple to nearly white flowers april and may
Funereal Duskywing butterfly LARVAL HOST, pollinated by several native bee species
habitat-modifying keystone species
When you see a desert ironwood tree (Olneya tesota) you know you are in the Sonoran Desert proper. Found in desert washes and on low hills, often in gravelly to silty soil, below 3,000 feet, the desert ironwood's range is identical to the range of the Sonoran Desert. The only other organism that has such an identical range is the lesser long-nosed bat.
Desert ironwood is also a habitat-modifying keystone species, that is, a species that exhibits strong influences on the distribution and abundance of associated species. It is important as a nurse plant for many younger plants--providing shade and protection as they grow, as well as providing habitat for animals that make nests in the trees, as well as below the trees.
Possessing one of the hardest and heaviest woods in the region, desert ironwood grows slowly but steadily, and some trees are estimated to be about 800 years old! It is remarkably resistant to rotting, perhaps because its heartwood is rich in toxic chemicals that make it essentially non-biodegradable--a dead ironwood tree trunk will persist as long as 1600 years!
Usually a multi-trunked tree, sometimes single-trunked, plants can grow as large as 50 feet tall, but normally much shorter, especially in Arizona. More commonly in our area they get up to about 30 feet tall and wide. They bloom in April - May and are followed by seed pods. Native bees are the primary pollinators of ironwood. The tree is also a larval host to the Rawson's metalmark (Calephelis rawsoni).
For information on using ironwood as food (especially the seed) check out Desert Harvesters page on Ironwood.
Grow ironwoods in full sun with moderate to low water. It is hardy to about 20º F
While Ironwood is not endangered or threatened, its populations dwindle annually over tens of thousands of square kilometers.