Herbarium: Medicinal Plants as Information

The Smelly, Antiseptic Wonder: A look at the history, form and medicinal properties of Larrea tridentata

Larrea tridentata is a plant of many names, commonly known as a creosote bush (named for the plant’s smell's reminiscence to creosote tar) in addition to the multiple local and cultural names by which the plant is referred: chaparral, gobernadora, and hediondilla. While the current scientific name of the plant is Larrea tridentata, this nomenclature has changed over time, first being classified as Larrea mexicana (named in reference to one area the plant is native) in the Materia Medica. Larrea tridentata current species denotation refers to the plant's three-toothed leaves. The plant’s maintanining genic name is named for bishop Juan Antonio Hernández Pérez de Larrea, a patron of science and botanist. Species belonging to the Larrea genus vary in physical characteristic differences, ranging from leaf shape and fruit production to petal shine, defining qualities oft present in a plant's species (Larrea cuneifolia meaning wedge-shaped leaves, Larrea nitida meaning bright).

Looking at the Larrea tridentata specimen from the UCLA Herbarium, collected by E. Armstrong, March 28th, 1934 in the Mojave Desert, Kern County, there are two branches saved, each at a different stage of maturity. In seeing the branch at two places in the plant's cycle comparative observation of the plant at different stages is possible, providing a fuller understanding of the plant's growth and flowering cycle. For example, after a flower is spent, it gives way to a fuzz-covered node.

Observations of Larrea tridentata were supplemented through the observation of living specimen Larrea nitida in the Mildred E. Mathias Botanical Garden, and early illustrations of Larrea tridentata, then Larrea mexicana. The UCLA Herbarium Larrea tridentata specimen's discoloration over years of drying made consultation of this imagery and a closely related living specimen paramount to this examination and illuminated the differences between species of the same genus, specifically leaf shape. The value of supplemental comparison can be seen in the recognition that the dense foliage observed on the Larrea tridentata specimen sample likely functioned in part to advantage the bush’s water retention in its native desert climate with little precipitation, a connection only made possible through observing the shallow root system of Larrea nitida.

While Larrea tridentata is now named for a physical trait, it is the plant’s chemical characteristics that endow Larrea tridentata with its particular significance, both as a long-surviving species and within the plant’s medicinal properties. Larrea tridentata, widely known for its resilience in a harsh desert environment, produces chemical compounds which serve to protect the plant from damage insects, pathogenic fungi, and herbivores might otherwise inflict. Larrea tridentata’s chemical constitution of lignans, a protein compound, and flavonoids both of which give the bush antiseptic properties. It is because of the Larrea tridentata’s active antibacterial properties, that the leaves and twigs from Larrea tridentata have traditionally been made into tea, powder, poultice, functioning primarily as an antiseptic to destroy germs, and as an emetic to clear the stomach of harmful substances and toxins by native peoples. Boiling the bush’s leaves into tea treated diarrhea, stomach pain, and served as a mucoactive agent, while topical application would treat chest complaints and skin conditions, including wounds and sores. Larrea tridentata was also historically used to treat toothaches, with the sap from the plant’s shoot tips being dripped into cavities, in addition to wide usage in treatments for rheumatism, venereal infections, urinary infections, and cancers. Acknowledgment of the historic implementation of the Larrea tridentata in medicinal practice has exciting implications for the future of medicine.

References

Stein, M. 1998. “Management Recommendations for Threeleaflet goldthread (Coptis trifolia (L.) Salisb.)”. Accessed March 8. https://www.blm.gov/or/plans/surveyandmanage/MR/VascularPlants/section7.htm#Ecology

Wikipedia. n.d. “Larrea tridentata”. Accessed March 8. https://en.wikipedia.org/wiki/Larrea_tridentata#Habitat

Hortipedia. n.d. “Coptis trifolia”. Accessed March 8. https://en.hortipedia.com/Coptis_trifolia

Sullivan, Janet. 1992. “SPECIES:  Coptis trifolia”. Accessed March 8. https://www.fs.fed.us/database/feis/plants/forb/coptri/all.html#DISTRIBUTION%20AND%20OCCURRENCE

Marshall, K. Anna. 1995. “SPECIES: Larrea tridentata”. Accessed March 8. https://www.fs.fed.us/database/feis/plants/shrub/lartri/all.html

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