Olneya tesota

Botanical Name

Olneya tesota A. Gray

Common Name(s)

  • desert ironwood
  • palo fierro (Spanish)
  • tesota (Spanish)

Synonyms

Legume Clades

Papilionoideae , 50-kb Inversion Clade , NPAAA Clade , Hologalegina , Robinioid Clade , Olneya

Native Geographic Range

  • Southwestern North America

IUCN Status

NT (Near threatened)
See IUCN Red List Assessment

Growth Form

tree

Cultivation Status in AZ

Native

Description

Semi-evergreen trees often growing 20--30 ft (6--9 m) high with an irregular canopy. The twigs are armed with short, usually paired spines at the nodes. The bark is smooth and gray, and splits into strips with age. The finely hairy, gray-green, once-pinnate leaves are mostly 1.2--2.2 in (3--6 cm) long and have 6--16 small leaflets. The foliage is tardily drought-deciduous and leaves are also shed prior to flowering. Flowers are small, pea-like, and are pale, dusty pink (rarely white), and are produced in profusion in small inflorescences. Flowering is typically in late April and May but does not occur every year.

Habitat

Widely distributed across the Sonoran Desert in the southwest U.S. and northwestern Mexico and in thornscrub along the southern margins of the desert in Mexico. The trees are often abundant across their range and occur in various soils on plains and valley, on slopes, and along drainages.

Uses

Desert ironwood serves as a nurse plant for many other species of plants and provides food and shelter for various wildlife species. The wood is hard and very dense, hence the common names, and will not float. The wood is commonly used to make carvings in Mexico and is an excellent fuelwood and source of charcoal. Populations of desert ironwood in Mexico are being overharvested.

Horticulture

Desert ironwood is propagated from scarified seeds. The trees have a modest growth rate with irrigation. They will survive on rainfall within their range once established though growth is greatly reduced. Desert ironwood tolerates extreme heat. Pruning helps young plants develop a more upright growth habit. Desert ironwood is hardy to ca. -18° F (-7.7° C) though the foliage may be damaged below -22° F (-5.5° C). The trees are rarely damaged by high winds. Due to the spiny stems, desert ironwood should be located away from high traffic areas. The leaves, fruits, and flowers are small so litter is not a significant issue with this species. Desert ironwood can live for centuries. It can serve as a focal point in a landscape and provides welcome shade from the desert sun. It is suitable for planting in street medians medians and other locations where maintenance is infrequent. Desert ironwood is readily available in various sizes from commercial nurseries in Arizona.