This species is globally distributed and is abundant throughout its range.
Considerable taxonomic uncertainty exists regarding the genus Usnea (Clerc 1998). Future taxonomic changes are likely which could further circumscribe the species’ range. However, it is extremely abundant and has a very broad distribution, some areas of the world considering it to be rare. Taxonomic changes are unlikely to result in changes to status of the species.
Synonomy: Usnea marocana Motyka, Lichenum Generis Usnea Studium Monographicum. Pars Systematica 2: 354 (1937) [MB#412152]
Bloody Beard Lichen (Usnea mutabilis) is a globally distributed species. It is broadly distributed in eastern North America ranging from Nova Scotia to Florida and west to Minnesota and Texas (Brodo et al. 2001). It also occurs in southern California and Baja California Norte (Nash et al. 2002). The species also occurs in southern Europe within France, Spain, Portugal, and Italy (Fos & Clerc 2000), northern Africa in Morocco (Azami et al. 2004), the Canary Islands, and Japan (CNALH 2020). Moreover it has been reported from southern portions of Far East Russia (Ohmura et al. 2017). One report from Jamaica has yet to be confirmed.
Though the species is rare in some parts of its range, it is abundant in the southeastern United States (Clerc and Herrera-Campos 1997) and its population is not likely to meet any thresholds for listing under a threatened status.
Population Trend: Uncertain
Usnea mutabilis is a fruticose lichen species that prefers bark substrates and humid habitats. It rarely occurs on rock, and additionally can be found in the chaparral and other coastal shrub communities, on Quercus spp., and other diverse shrubs ( Brodo et al. 2001, Nash et al. 2007).
Like many other lichen species, the primary threat to Usnea species in North America is air pollution including heavy metal contamination, and acid rain derived from sulfur and nitrogen dioxides (Cameron et al. 2007). Usnea species are considered intermediate indicators of air quality and are somewhat tolerant of poor air quality. Impacts from industrial and urban pollution sources are likely to be most severe within a few tens of kilometers of urban and industrial sources. The specific impact of collection on the species is not well understood and additional study of harvest pressure is needed (American Herbal Products Association 2012). Recent observations of the species in urban areas have been noted as evidence of long term air quality improvements and suggest range expansion may be occurring in previously extirpated urban areas (Dorey et al. 2019).
The species incidentally occurs in several protected areas (IUCN and UNEP-WCMC 2020).
The Minnesota Department of Natural Resources listed U. mutabilis as threatened in 2013 under their states guidelines. Additionally other U.S. states have it on lists of concerns.
Members of the genus Usnea have long been used for medicinal, and cosmetic purposes and as dyes. Investigation into the pharmacological applications of the genus are ongoing and traditional medicines indicated the genus for use treating upper respiratory ailments, infection, and indigestion (Prateeksha et al. 2016). Difficulty distinguishing between taxa at the species level, and inadequate reporting requirements from harvesters prevents accurate assessments of the level of harvest for the species. Estimates of harvest levels at the genus level, derived from voluntary surveys of herb dealers in the United States demonstrates harvest levels exceed 1,000 pounds of material during most years between 1999 and 2010 (American Herbal Products Association 2012). The overwhelming majority of this material is derived from wild collection.
American Herbal Products Association 2012. Tonnage Surveys of Select North American Wild-Harvested Plants, 2006–2010. American Herbal Products Association, Silver Spring, MD.
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Clerc, P. 1994. Comment Usnea mutabilis Stirton, une espèce nord-américaine, se cache en Europe sous le nom d’Usnea marocana Motyka - Une contribution à la systématique du genre Usnea (Ascomycètes lichénisés). Bulletin de la Société linnéenne de Provence. 45. 309-316.
Clerc, P. 1998. Species Concepts in the Genus Usnea (Lichenized Ascomycetes). The Lichenologist, 30, 4–5, 321–40.
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Dorey, J. E., Hoffman, J. R., Martino, J. L., Lendemer, J. C. and Allen, J. L. 2019. First Record of Usnea (Parmeliaceae) Growing in New York City in Nearly 200 Years. The Journal of the Torrey Botanical Society, 146, 1, 69.
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Ohmura, Y., Skirina, I. and Skirin, F. 2017. Contribution to the Knowledge of the Genus Usnea (Parmeliaceae, Ascomycota) in Southern Far East Russia. Bulletin of the National Museum of Nature and Science Series B, Botany, 43, 1–10.
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