Larrea tridentata – “Creosote Bush”
Also Known As: Covillea, Greasewood, Chapparal, Gobernadora, Hediondilla, Shegoi
Family: Caltrop (Zygophyllaceae)
Bloom Period: Apr-May
Form: Shrub
Habitat: Widely distributed in sandy and gravelly soils on flats and slopes throughout the Mojave, Sonoran and Chihuahuan Deserts, often as the dominant or co-dominant species
Leaves: Pairs of oblanceolate leaflets, resinous, evergreen
Translation: “Larrea” is “named for Bishop Juan Antonio Hernández Perez de Larrea (1731-1803), a Spanish “promoter of science”; “tridentata” is Latin for “three-toothed,” referring to the three-lobed leaf shape.
Notes: The most common plant in Joshua Tree Country, often dominant or co-dominant with White Burro-Sage. Originally from South America, it appeared in North America 12-14,000 years ago. How it traveled that distance is a mystery since there is no trace of it in the thousands of miles between and human migrations in that time period were spreading from north to south. One theory is that its seeds caught rides in the tail feathers of migrating Plovers!
Creosote Bush is the most drought-tolerant plant in North America, and can survive two years with no precipitation whatsoever and needs only 1/2 inch (13 mm) of rain to flower. Though it grows from seed, it also reproduces by forming clonal colonies: plants slowly expand outward from their crowns, and eventually the original center dies, making a ring of plants. The oldest known such clonal-colony – the “King Clone” – is near the town of Landers in the heart of Joshua Tree Country and is estimated to be over 11,000 years old, making it one of the oldest living creatures on Earth.
People often notice how evenly spaced Creosote Bushes are, as if placed on purpose. This distance is the product of chemicals exuded by the roots that discourage the growth of other Creosote Bushes and also White Burro-Sages. Other plants are not affected, and indeed the Creosote Bush serves as a nurse plant for many desert plants, sheltering them from wind and providing a little shade. The Spanish name, Gobernadora, which means, “governess,” aptly describes this mothering role (though some texts mis-translate it as “Governor” and attribute the name to the plant’s supposed domination of the space around itself).
Moisture causes the waxy coating of the leaves to release a distinctive odor. After a rain the air is famously filled with this distinctive scent, hence the Spanish name, Hediondilla, “little stinker.” Some have compared the odor to that of creosote – the petroleum product – which is how the plant got its common name. Personally, I would not make this characterization, and find the scent quite pleasant (as do many others). One of the common names, “Covillea,” is a previous designation for the Larrea genus and honored Frederick Vernon Coville (1867-1937), a curator of the U.S. National Herbarium and botanist on the Death Valley Expedition of 1890-91.
Western herbalists often inexplicably refer to this plant as “Chapparal.” The word comes from the Spanish, “chapparo,” meaning “dwarf evergreen oak,” and specifically refers to scrub oaks (such as the Turbinella Oak in this guide), which are unrelated plants. Neither is the ecosystem type known as “chappara” ever home to it. Claims that the plant has anti-cancer properties are highly publicized but have not been substantiated.
Native American Uses: The Pima call Creosote Bush, Shegoi, “the Mother of All Plants”; in their creation mythology, it was the first plant placed on Earth. It is easy to see why it was given this prominence, given its many uses to the Pima and many other Native Americans. Injured muscles, aches and pains, and wounds were treated by the Cahuilla, Kumeyaay, Isleta, Kawaiisu, Paiute, Tohono O’odham, Pima, and Yavapai with poultices and infusions of the disinfectant leaves that were applied topically. Intestinal issues were eased by the Cahuilla, Coahuila, Mahuna, Paiute, Pima by drinking an infusion of the leaves. Such infusions were also taken internally for colds by the Hualapai, Paiute, Pima and Shoshone and for sore throats and respiratory issues by the Cahuilla, Hualapai, Pima and Yavapai. Difficulty in urinating was allayed with the plant by the Pima and Shoshone. Gonorrhea and venereal disease were treated with the plant by the Paiute, Shoshone and Yavapai. The Cahuilla, Tohono O’odham and Pima used it as an emetic (vomit inducer), sometimes to break fevers. Dandruff was treated with an infusion of the plant by the Mahuna and Pima. The Cahuilla treated cancer with an infusion of the stems and leaves, and also gave it to their horses for colds. The Tohono O’odham applied a poultice of the macerated leaves on bites from insects, snakes, spiders and scorpions. The Pima held an infusion of the plant in the mouth for toothaches, used the smoke from the burning plant material to stimulate the weak or lazy, and placed leaves in the shoes as a deodorant (as did the Isleta).
The Kawaiisu used the wood to make sharpened digging sticks and harvested resin from the Lac Scales for tool handles. The resin was also used for mending pottery and water-proofing baskets. The Seri smoked the galls made by the Creosote Gall Midge. The Tohono O’odham used the branches to brush the spines off of prickly-pear cacti and to shade tobacco plants, the wood for arrows and hide-stretching stakes, and the charcoal for greenish-blue tattoos. Interestingly, the plant held a special place for women and childbirth: the Mahuna used it treat menstrual cramps and the Tohono O’odham built menstruation huts with the wood, applied heated branches to ease childbirth, put plant material in the beds of women who had menstrual cramps or had given birth, applied powdered leaves to the newborn infant’s navel to help it heal, and, finally, used a topical wash of the leaves on the breasts as a galactagogue (to encourage milk-production).
Animal Associations: Leaves are the exclusive diet of the Creosote Bush Grasshopper, the staple food of the Desert Iguana, a mainstay of the Chuckwalla lizard, one choice among many for the Mojave Ground Squirrel, the major ingredient of the Desert Woodrat’s winter sustenance (though it chooses the least resinous leaves available), and fodder of last resort for the Black-Tailed Jackrabbit. The Verdin, an insectivorous bird, takes cover in its branches where it seeks food. Fruits are eaten by the Round-Tailed Ground Squirrel. Small mammals often burrow their homes at the base of the shrub, digging tunnels amongst the roots to protect themselves from digging predators; such mammals include the White-Tailed Antelope Ground Squirrel, Kangaroo Rat, Rock Squirrel and many species of mice.
The plant commonly hosts Lac Scales, insects that exude a sticky secretion. Ants harvest it and protect the Lac Scales from other insects in order to safeguard their food supply. Twenty-two species of bee are “oligolectic” with the Creosote Bush, that is, they feed exclusively off its flowers; these include three species of Mining Bees, two species of Plasterer/Polyester Bees, a Mason/Leafcutter Bee and a bee in the Dasypodaidae Family. Dozens of species of insect are entirely dependent on the Creosote Bush such as the Creosote Bush Katydid, the Desert Clicker Grasshopper, and the Creosote Gall Midge.
The Creosote Gall Midge is a fly whose life is centered around the plant. The female uses her ovipositor to insert eggs into a stem, along with fungal spores she keeps in a special pocket on her body (which is called a mycangium). The plant is induced to form a gall at that spot, which becomes lined with the thread-like vegetative growth of the fungus (which is called the mycelium). When the eggs hatch, the larvae eat the fungus. The the adult flies eventually emerge from the gall and the whole cycle starts all over again. These galls are not harmful to the plant. One of these galls is pictured in the inset photo.