Warty Beard Lichen (Usnea ceratina) has a global distribution including much of North America and Mexico, the eastern slope of the northern Andes, the Atlantic forests of southern Brazil, western Europe, the Caucasus Mountains, the Ural Mountains, northern Thailand, Japan, and coastal areas of Australia. The species is locally abundant but uncommon throughout its range suggesting it has a very large population. Along with other species of Usnea, the species is likely to be collected for medicinal preparations. Threats to the species include air pollution and habitat loss. Due to its very large range and suspected large population, the species is listed as Least Concern.

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. Taxonomic changes are unlikely to result in changes to status of the species.

Warty Beard Lichen (Usnea ceratina) has a global distribution including much of North America and Mexico, the eastern slope of the northern Andes, the Atlantic forests of southern Brazil, western Europe, the Caucasus Mountains, the Ural Mountains, northern Thailand, Japan, and coastal areas of Australia (CNALH 2020, GBIF 2020, Nash et al. 2007). It occurs at elevations ranging from 0 to 3,100 meters (GBIF 2020).

The species is noted to be locally abundant though uncommon throughout its distribution (Clerc 2004) and is therefore unlikely to meet any population thresholds for listing under a threatened status.

Warty Beard Lichen subpedulous to pendulous lichen which occurs in coastal to montane areas on bark (typically Pinus spp. or Quercus spp.) (Nash et al. 2007)

Like many other lichen species, the primary threat to Usnea species is likely to be 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. Habitat loss may also threaten some subpopulations particularly in the Sierra Madre Occidental, where rapid deforestation is occurring (Novo-Fernández et al. 2018).
The specific impact of collection on the species is not well understood and additional study of harvest pressure is needed.

The species incidentally occurs in several protected areas (IUCN and UNEP-WCMC 2020).

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.

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Clerc, P. 2004. Notes on the genus Usnea Adanson. II. Bibliotheca Lichenologica, 88, 79–90.
Clerc, P. 1998. Species Concepts in the Genus Usnea (Lichenized Ascomycetes). The Lichenologist, 30, 4–5, 321–40.
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Nash, T. H., Gries, C. and Bungartz, F. 2007. Lichen flora of the greater Sonoran Desert region. Vol. 3, Vol. 3,. Lichens Unlimited, Arizona State University, Tempe.
Novo-Fernández, A., Franks, S., Wehenkel, C., López-Serrano, P. M., Molinier, M. and López-Sánchez, C. A. 2018. Landsat time series analysis for temperate forest cover change detection in the Sierra Madre Occidental, Durango, Mexico. International Journal of Applied Earth Observation and Geoinformation, 73, 230–44.
Prateeksha, Paliya, B. S., Bajpai, R., Jadaun, V., Kumar, J., Kumar, S., Upreti, D. K., Singh, B. R., Nayaka, S., Joshi, Y. and Singh, B. N. 2016. The genus Usnea: a potent phytomedicine with multifarious ethnobotany, phytochemistry and pharmacology. RSC Advances, 6, 26, 21672–96.
SEINet 2019. SEINet Portal Network. Available online at http//:swbiodiversity.org/seinet/index.php [Accessed 1 April 2019].