Old Man's Beard: A Medicinal Lichen

By Ana Maria Ruiz

Feb 7 2020

Usnea is a genus of lichen, commonly known as Old Man’s Beard.  Lichens consist of a fungus and a photosynthesizing partner such as algae or cyanobacteria living together in a symbiotic relationship. Usnea has a pale greenish thallus. It is round, stringy, and is generally found growing and hanging on the branches and trunks of trees.

Usnea has been used in traditional herbal medicine in cultures around the world for its antimicrobial properties. It is alleged that Hippocrates used U. barbata to treat urinary afflictions and that U. longissima was used by the Chinese as an expectorant and to heal wounds (Cansaran et al., 2006). Usnea has been used in traditional Native American medicine to treat lungs, intestines, throat, sinuses, and the urinary and reproductive system.  It is considered a sacred “herb of the North”. The Dakota call it Chan wiziye, translating to “on the north side of the tree” or “spirit of the north wind” (Buhner, 1996). Usnea extracts are still a common ingredient in herbal tinctures today.

Lichens commonly contain secondary metabolites which are often found in no other organisms. Usnic acid, in the chemical class of dibenzofurandiones, is responsible for the lichen's antimicrobial properties and its pale greenish color.  Additionally, usnic acid has been shown to exhibit multiple antibiotic and analgesic properties. It is commonly used in perfumery, cosmetic applications, toothpaste, creams, mouthwash, deodorants, and sunscreen (Cansaran et al., 2006). More testing is needed to fully study usnic acid properties for medical-grade applications.

Many Usnea species have become rare due to their long history of use and their sensitivity to air pollution. It is important that Usnea collected for research and other harvesting be conducted in a sustainable and ethical manner.  It is illegal to collect in national parks, and only limited lichen collection is allowed on public lands like the Nantahala and Pisgah national forest where Usnea species are common (Allen et al., 2019). Where collection is allowed it is recommended that sustainable harvesting practices are observed: fallen branches covered in Usnea or detached Usnea from its substrate is more acceptable than harvesting directly off trees. Harvesting should also be done in a way that is respectful to the surrounding ecology. For more insightful reading on this subject, I recommend Robin Wall Kimmerer’s book, Braiding Sweetgrass.  

Above are a variety of Usnea species images taken in the field, before being collected for the herbarium. These were collected in the Great Smoky Mountains by James Lendemer and Erin Tripp.  

More about: LichensUseful plants

Allen, J., Boggess, L., and Lendemer, J. 2019. Likin’ our lichens: Sustainability harvesting Usnea in WNC. Mountain Xpress. 8-9.  Retrieved September 27, 2019, from

Buhner, S. H. 1996. Sacred plant medicine: The wisdom in Native American herbalism. Bear & Company, Rochester, VT, p. 133-135.

Cansaran, D., Kahya, D., Yurdakulol, E., and Atakol, O. 2006. Identification of Usnic Acid from the lichen Usnea species of Anatolia and antimicrobial activity. Zeitschrift fur Naturforschung C 61(11-12): 773-6. DOI: 10.1515/znc-2006-11-1202. Retrieved September 27, 2019, from https://www.researchgate.net/publication/6509978_Identification_and_Quantitation_of_Usnic_Acid_from_the_Lichen_Usnea_Species_of_Anatolia_and_Antimicrobial_Activity

For more information about usnic acid:

Araújo, A. A. S., de Melo, M. G. D., Rabelo, T. K., Nunes, P.S., Santos, S. L., Serafini, M. R., Santos, M. R. V., Quintans-Júnior, L. J., and Gelain, D. P. 2015. Review of the biological properties and toxicity of Usnic Acid. Natural Product Research: Formerly Natural Product Letters, DOI: 10.1080/14786419.2015.1007455. Retrieved September 27, 2019, from https://www.researchgate.net/publication/272844556_Review_of_the_biological_properties_and_toxicity_of_usnic_acid