Creosote Bush (Larrea tridentata) — Spadefoot Nursery, Inc.

Creosote Bush
Larrea tridentata

Family: Zygophyllaceae

This is one of our most important low desert shrubs: this plant is evergreen unless experiencing severe drought. Typically these shrubs grow to 6’ tall or more x 8’ wide. Some populations grow very tall (up to 12’) and slender—especially plants that grow in the dunes of western Arizona. One horticultural selection (called Yuma) is from such a population. The foliage is sticky, shiny, and aromatic. This is one of the plants that contribute to that “desert rain” smell. Yellow flowers can appear almost any time of year. Flowers are followed by fuzzy globose capsules that contain 5 seeds.

The King Clone ring in the Mojave Desert is a creosote bush clonal colony—the stems of a single plant have been rerooting for thousands of year. The clonal colony is estimated to be about 11,700 years old.

Plant in full sun, low water needed when established, hardy to 0° F. Good drainage is very important. Getting this plant established is different than most other native shrubs. Firstly, this species doesn’t like growing in containers, especially smaller containers. When planted, they should receive some supplemental water to become established, but nowhere near as often as other native shrubs. Immediately start putting space between watering. Established plants can live on rainfall, but look better with monthly watering, especially during drought.

Photo by Sue Carnahan, SEINET
Larrea tridentata on iNaturalist

Though reputed for preventing other plants from growing beneath this species, this is not true for the Sonoran Desert. In fact, creosote bush in our region is more of a nurse plant—there is enough rainfall to not allow the growth inhibiting (allelopathic) compounds to collect. In the very dry Mojave Desert, where little else grows, the allelopathic compounds are much more inhibiting. Creosote bush is crucial to the survival of many native bee species as a nectar plant. Many insects are specific to this species, such as the creosote katydid (Insara covillei), the creosote bush walking stick (Diapheromera covilleae), and the creosote grasshopper (Bootettix argentatus), which are so camouflaged that they are very difficult to find. Lac insects (Tachardiella larreae, a scale insect) can occasionally be found on its stems. Large galls found on creosote bush are produced by the large creosote bush gall midge (Asphondylia auripila) and there are several other species of Asphondylia that make other various galls on creosote bushes that are more inconspicuous; larvae of these small flies live in the protective mass of tissue produced by the flies. Creosote bush is a larval food plant for various geometrid moths (family Geometridae) and bagworm moths (family Psychidae).

Creosote bush is an important medicinal plant that has been used for numerous ailments. Be careful not to use this plant internally for prolonged periods. Also used topically for numerous ailments.

Widespread and common on dry plains and mesas below 5,000 ft. in southern and central California, southern Utah, Arizona, New Mexico, Texas; south through southern Mexico.

There are 5 species of Larrea in the Americas. Larrea is named for Bishop Juan Antonio Hernandez Perez de Larrea (1731-1803) in Valladolid, Spain, while tridentata means three-toothed, the appearance of the leaves being three-toothed. Many botanists believe that this species is the same as the South American species L. divaricata.