Usnic acid was identified in many genera of lichens including Usnea, Cladonia, Hypotrachyna, Lecanora, Ramalina, Evernia, Parmelia and Alectoria. Although it is generally believed that usnic acid is exclusively restricted to lichens, in a few unconfirmed isolated cases the compound was found in kombucha tea and non-lichenized ascomycetes.
Usnic acid has been found in various genera of lichens, including Usnea, Cladonia, Hypotrachyna, Lecanora, Ramalina, Evernia, Parmelia and Alectoria. Although it is generally believed to be exclusive to lichens, there have been isolated cases where the compound was discovered in kombucha tea and non-lichenized ascomycetes.