Creosote: Ancient Desert Shrub That Smells Like Rain

Call of the Southwest, Nature

Creosote: Ancient Desert Shrub That Smells Like Rain

Creosote is a hardy Pleistocene invader with rain-volatilized, aromatic leaves. Creosote is a medicinal plant and bees’ partner.

“The desert is unpredictable, enigmatic.  One minute you will be smelling dust.
The next, the desert can smell just like rain.”
(quote above by Gary Nabhan from The Desert Smells Like Rain)

Following recent spring rains in the lower desert parts of central Arizona, my nose was overwhelmed with the heavy pungent scent of the aromatic creosote volatilized by the rain. The air was thick with palpable presence of creosote.

As a native Arizonan, this smell is a positive imprint that signifies rain!  I instinctively felt energized. I have always taken creosote presence for granted, but decided this spring, resin-scented day to get to know more about this iconic desert shrub.

Until we take time to really look, how little we know of the intricate lives of the plant and animal beings that surround us. Even in our urban cocoons, we are woven within complex ecosystems exquisitely adapted to our local soils, light, moisture and temperatures.

On a cellular level we are in vibration with these qualities of place in every moment. Only our busy minds take us away from this direct knowing. What lessons do they have for us to thrive and adapt to change?

Creosote is a Hardy Pleistocene Invader

At the end of the last Ice Age, about 11,000 years ago,  as the climate became warmer and drier, the junipers who used to inhabit the lower regions of the Southwest retreated to the nearby mountains, and creosote appeared on the scene.

During this period this hardy invader shrub rapidly colonized  after unknown long distance carriers (possibly migrating plovers) brought the seeds north from Argentina.  Even hardy creosote would not have been able to come directly north across the wet tropical forest of Central America.

Today creosote, Larrea tridentata, is a dominant or co-dominant member of most plant communities in the Mohave, Sonoran, and Chihuahuan Deserts.

Creosote Ancient Growth Rings

This hardy drought tolerant perennial may be the oldest living plant in North America.

Jonathan DuHamel explains:

“The branches of the plant will live several centuries and die out, but the root crown produces new branches in a ring around the original plant. With time, this ring expands outward as old branches die and new branches take their place, and eventually become separate bushes which are clones of the original seed. If the prevailing wind is especially strong, only the clones downwind of the parent plant will survive, forming a line of plants instead of an expanding ring.”

These mysterious looking growth rings then become mounded up with sand in the center.

“In a few areas of the Mojave Desert clonal creosote rings have been found that are several yards in diameter. Near Lucerne Valley, “King Clone” has an average diameter of 45 feet! Using radiocarbon dating and known growth rates of creosote, scientists have estimated the age of “King Clone” as 11,700 years. Some of these common residents have been here continuously since the last ice age.”  Harold DeLisle, PhD.

Creosote Ecological Associations – Volatile Leaves

In just these few thousand years, creosote has adapted to the different desert environments and added more chromosomes.

It has evolved associations with more than 60 species of insects, including 22 species of bees that feed only on its flowers.

These bees can lay in larval form near the shrubs also waiting for the rain to bring them to life. Desert creosote bushes provide shelter and shade for crickets, grasshoppers and other desert insects.

Larger animals, including desert tortoises, kangaroo rats, lizards and desert fox make their beds under the creosote bush or take refuge from predators and hot daytime temperatures in the plant’s shade.

While the creosote bush is inedible to most browsing animals, some small mammals such as the black-tailed jackrabbit consume the seeds and some species of rats eat the twigs.

Creosote is an aromatic desert shrub whose stems and evergreen leaves contain a sticky resin.

This is NOT to be confused with the creosote that is used for wood preservation, which is a petroleum product distilled from tar.

Creosote, the desert shrub, resin screens the leaves against ultraviolet radiation, reduces water loss, and poisons or repels microbes and most plant-eating animals.

Waxy coating on creosote leaves prevents water loss and protects the plant from being eaten by most mammals and insects. During drought, the wax covered leaves shrivel but do not die.

When rains do come, the shallow, wide spread roots quickly take in water from the surrounding soil. The wrinkled leaves quickly rehydrate and turn bright green. Yellow flowers bloom followed by fuzzy little seeds.

Creosote in bloom in Verde Valley, AZ after spring rains.

Creosote blooming in Verde Valley, AZ

“Rain volatilizes that waxy coating which then produces a distinct, camphor-like odor which some desert dwellers call the smell of rain. You can often experience the odor by cupping some leaves in your hands and blowing on them. There is enough moisture in your breath to volatilize the wax. ” (Jonathan DuHamel).

Creosote as Medicine Plant

A Tohono O’odam friend of mine told me he prized creosote leaves as an incense to burn for ceremony. He also spoke of its strong purgative affects when used for cleansing. His ancestral people knew the inherit purifying qualities of this plant on both the physical and spiritual levels. These desert peoples had a living relationship with this extreme environment which helped them thrive.

The Apaches chewed and swallowed a small piece of creosote branch to cure diarrhea. Other tribes made a strong tea from the dried leaves to treat the common cold.

The resinous leaf nodes were used to soothe bruises and wounds. And a tea made from the leaves and sweetened with a little honey was said to greatly relieve kidney pain. (Harold DeLisle, PhD)

Folk medicine practitioners have used creosote for centuries as a salve or ointment, especially as an antiseptic and pain reliever. Creosote is known as a blood cleanser, an antioxidant, antiviral and antibiotic agent, and is used for infections, skin problems, and auto-immune diseases such as arthritis, and may help to lower blood cholesterol. It is currently under research as a chemotherapeutic agent for cancer, and shows promise.

I admire the rugged adaptability of this ancient plant. And when it rains, that sharp aroma brings potent “medicine” to my senses.

Creosote’s intelligent adaption to expanding from the circle outward reminds me of ancestral peoples’ ceremonial circles. Can the DNA of we modern day peoples respond as effectively to change, adapt and evolve? Can we burst into new life with infrequent “showers”?

posted July 5, 2006; updated January 7, 2017 and August, 2019

See other nature and cultural articles in our Spirit of Southwest Blog.