In the introduction topics such as lichen characters, taxonomy, habitats, and threatened taxa are discussed. Also, an overview of lichen research in Finland is provided. The detailed treatment of taxa includes genus and species descriptions as well as habitat data and distribution. Common synonyms and threat status are given. Each taxon is illustrated with a colour photograph, and distribution maps are given. An updated checklist of Finnish lichens, lichenicolous fungi, and some lichen-like fungi, altogether 1952 taxa, is provided.
![Suomen Rupijäkälät [Crustose Lichens of Finland]](https://ruslaniacdn.akamaized.net/pictures/books_photos/50/500162/si.jpg)
