The secret of lichens was concealed from Linnaeus
Linnaeus referred all the lichens to one genus, Lichen, and described more than 100 different species. He was not particularly interested in lichens. It was one of the last of his pupils, Erik Acharius, who would be called the father of lichenology. Acharius made the first detailed classification system for lichens. His work was the basis for modern lichenology.
Neither Linnaeus nor Acharius suspected that lichens are composed of two very different organisms. This finding was not made until the end of the 19th century. Since then it has been studied how the algae and fungus relationship works. More and more species have been described and today there are more than 15 000 species in many different genera.
There are about 2000 lichen species in Sweden. Some are better known than others. Star reindeer lichen is used to decorate the Swedish candle centrepiece in advent and the beard lichen is hanging on the forest trees where the air is clean. Lichens can grow on all possible substrates. They often grow on stone, bark or directly on the ground. There is still much left to find out about the lichens. At Uppsala University lichen research has been going on since the time of Linnaeus. Right now a Nordic lichen flora is being prepared.