Introduction to Parmeliaceae
The lichen flora of the Nordic countries, containing about 2,000 species, is regarded as one of the best known in the world. Lichenological research of the region has been continuous since the time of Erik Acharius (1757-1819), the 'father of lichenology', but there is no modern treatment of the region's impressive lichen flora. The last attempt was made in the 1870s by Th. M. Fries, but his major