Lichens of Finland is based on the two updated volumes of Finnish lichen guide books, which were published in Finnish in 2011 and 2015: Suomen Jäkäläopas (2011) and Suomen Rupijäkälät (2015). It was published as a single volume English language text in 2016 and proved popular. Out of print for a number of years is was then re-issued in a new edition in 2021. The book is noted for the exceptional quality of the colour photographs.
In total, 212 genera and 748 species, subspecies, or varieties are presented in detail. All macrolichens, as well as c. 300 crustose species (microlichens) come with a description, a handsome colour photograph and a distribution map. Other microlichens with uncertain nomenclature or distribution are not covered in the same way. A notable feature of the book is an updated checklist of all Finnish lichens, lichenicolous fungi, and some lichen-like fungi, comprising 1952 taxa in total.
An introductory section covers morphology, taxonomy, chemical characters, habitats and endangered species, identification and other topics. There is also a comprehensive list of all lichens, lichen parasites and lichen-like fungi found in Finland, with synonyms, distribution data and ecological descriptions, a total of 1952 taxa. The book also contains indexes with Swedish, Finnish and scientific names.