Lichens have been a difficult group for botanists to understand. Only in the 20^th century did they find their correct position among the fungi. This paper outlines the long and rather complicated course from Theophrastos, the first person to use the term lichen (about 300 B.C.) to the molecular evidence by Gargas and coworkers in 1995 that proved lichens to belong among the fungi. It was, however, not the first time this classification was proposed. The first to formally include lichens in the fungi was J. B. Payer in 1848, and Persoon had already around 1800 suggested this in a letter to Acharius. It then took nearly 200 years to become a generally accepted idea, but during that process many important observations, still worthy of attention, were made.