Muhlenberg's Smile

By Laura Briscoe, James Colin Lendemer

May 13 2019

Almost everyone can name an endangered charismatic megafauna. But most would be hard pressed to name an endangered lichen. Lichens, as well as fungi, algae, and bryophytes, are often overlooked in conservation efforts that focus on flowering plants and animals. But these groups of organisms can be very vulnerable to the same forces that endanger other organisms, if not more so - they often have very specific environments or substrates that restrict their ranges and can be extremely sensitive to pollution and other environmental changes. There are currently only two lichen species protected under the US Endangered Species Act, and others that may be protected at state levels, although most states do not have a full understanding of their lichen diversity. Our curator James Lendemer and a former NYBG graduate student, Jessi Allen, have been involved international colleagues assessing lichen species for the International Union for Conservation of Nature's Red List of Threatened Species. 

Herbarium specimens present a wealth of information about species: where they historically occurred, and in what abundance - data that can be used to assess population declines or disappearances (or growth!) today.  Muhlenberg's Smile (Rinodina chrysomelaena) is a species of lichen that was commonly collected in the 19th and early 20th century, but is now considered critically endangered. None of the nine populations documented prior to 1990 have been relocated, and of the two populations discovered post-1990 (both in 2010) only one is located within a protected area (Great Smoky Mountains National Park). The known populations occur on moist rocks in shaded forest, usually by waterfalls. Although Muhlenberg's Smile is now on the Red List, it still remains unprotected by state, federal, and international legislation.


Lendemer, J.C. 2016. Getting Lichens on the List - The IUCN Red List, That Is. Retrieved from (Accessed: 08 May 2019).

Lendemer J., Allen, J., McMullin, T. & Tripp, E. 2018. Rinodina chyrsomelaena The IUCN Red List of Threatened Species 2018: e.T80703073A80703076. Retrieved from: (Accessed: 08 May 2019).