Plant of the day  

Larrea tridentata (Creosote Bush, Chaparral)

Larrea tridentata, of the Zygophyllacceae family, commonly known as Chaparral or Creosote Bush, is a common inhabitant of the deserts of the Southwestern U.S. and Mexico. 

Description The Creosote bush is normally chest or head high. Creosote leaves are small and curled (Moore, 1989, p.27) with a yellow-green color, and have a "greasy-leathery" texture (Tilford, 1997, P.44). "the bark is reddish brown toward the base of the plant and progressively lighter (to almost white) on the smaller limbs. The flowers are minute and yellow; they eventually develop into oddly fuzzy, seed-bearing capsules" (Tilford, 1997, p.44).

One of the reasons for the Cresote's great success is the presence a highly toxic substance produced at its root that prevents other plants from growing nearby. Rainfall washes away the toxin allowing other plants to grow. Once the water drains off, the toxin is reproduced and the foreign plants are destroyed (Pyle, June 12, 1999). This ability ensures that the Creosote does not have to compete with other plant life for vital nutrients. 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. Ancient Growth Rings Ancient King Clone creosote circle 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, added more chromosomes and 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 that is used for wood preservation is a petroleum product distilled from tar. This is NOT to be confused with the aromatic desert shrub with the same name. The wild desert shrub has a strong, but pleasing smell. The stems and evergreen leaves of this plant contain a sticky resin that smells like (but doesn't actually contain) the wood preservative creosote. This 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. "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). Medicinal Uses The Creosote bush serves many medicinal purposes: cure of fever, influenza, colds, upset stomach, gas gout, arthritis, sinusitis, anemia, and fungus infections (CRC Ethnobotany, June 12, 1999). Creosote also has antimicrobial properties, making it a useful first aid. It is also beneficial in the treatment of allergies, autoimmunity diseases, and Premenstrual Syndrome (Moore, 1989, p.29). Creosote serves as an analgesic, antidiarrheal , diuretic, and emetic. When used as a tea, the leaves and small twigs must be gathered, washed, and dried in the sun. The useable parts must then be ground into a powder and stored in a glass container because of the oils produced. Creosote can be used on the skin as a tincture or salve, and can be taken internally as a tea or capsule (Moore, 1989, p.26). Although there are such a variety of medicinal purposes the Creosote serves, use of this plant is controversial to some. According to research "chemical constituents in Creosote bush may inhibit the growth of cancerous cells, but other studies have shown exactly the opposite" (Tilford, 1997, p.44). Another reason for the controversial use of Creosote bush is because of its "potential toxic effect on the liver" (Chevallier, 1996, p.224). Non-Medicinal Uses In addition to medicinal purposes, the Creosote bush is used as livestock feed, firewood, and roofing material for adobe houses (Mabry, 1977, p.252). It can be used to prevent rancidity of vegetable oils, as a mild sunscreen or massage oil. It also serves as a disinfectant for homes, an insecticide, as fish poison and fuel (Hocking, 1997, p.431). References Chevallier. Encyclopedia of Medicinal Plants. Dorling Kindersley, London, 1997. Mabry. The New Age Herbalist. Gaia Books Ltd., London, 1988. Moore. Medicinal Plants of the Desert and Canyon West. Museum of New Mexico Press, Santa Fe, NM., 1989. Pyle, June 12, 1999. CRC Ethnobotany, June 12, 1999. Tilford, 1997.