The Papago Indians called it, and we echo their thoughts — the desert smells like rain. Even as the humidity rises before the rain, that special smell permeates the air, our nostrils flare, and we can feel the softness of a smile move up into our eyes as our lungs expand to take in a deep draught of air. Where, but the desert, is the gift of rain more gladly welcomed or more richly heralded?
Where does that smell come from? From our most common and, some feel, one of our most beautiful desert shrubs, the creosote bush, Larrea tridentata. The creosote originated in Argentina and invaded North American during the formation of our deserts sometime between 10,000 and 14,000 years ago. How it got here has been long debated but a good guess might include a ride in the tail feathers of migrating plovers. A sticky resin covers the stems and evergreen leaves. When activated by moisture it’s smell resembles the acrid petrochemical product used to preserve wood.
It is not unusual to ignore the common things living around us. Since the creosote is the commonest plant in our hot western deserts, it is often overlooked. This is a mistake since its success is based on a number of extraordinary abilities, not the least of which is its ability to go without water for long periods. Part of its secret is the resin which protects the leaves from ultraviolet radiation, reduces water loss, and poisons or repels most microbes and planteating animals. Because of its extensive root system the creosote is able to monopolize soil nutrients, preventing grasses and other plants from taking hold. Its taproot is able to grow 15 feet into the soil and the lateral roots, which also contain chemicals that discourage neighbors, can reach into more than 50 square yards of surface soil.
It would seem that few plants stand a chance against this aggressive invader, but that idea needs a closer examination. Creosote may be the only shrub growing in certain dry areas but in situations where water is not so limiting, such as on alluvial fans, they are abundant and hospitably share their resources.
Researchers Jack Schultz and Ted Floyd found that “many, including the saguaro cactus, begin life in the shade of a creosote plant “nurse bush.” Side-blotched lizards, desert iguanas, snakes, toads, and termites burrow beneath the shrub, and the chuckwalla feeds on its flowers and fruits. Ten or twelve species of small mammals depend on it for food, nesting sites, and refuge from the elements. Kangaroo rats consume its seeds, and jackrabbits prune its branches. Local birds, such as the verdin, black-throated sparrow, and black gnatcatcher, as well as scores of migratory visitors frequent the bush for seeds and insects. Generations of Native Americans have used the extracts of creosote bush as antiseptics and treatments for arthritis and rattlesnake bites. Its resin was once used to waterproof baskets and fix arrowheads to shafts. Today, some of the resin’s more than fifty components are thought to be effective in shrinking cancerous tumors, others are consumed as dietary antioxidants or used as food preservatives.”
~ Pat Flanagan