The Swedish taxonomist Carl Linnaeus described 110 lichen species in his various works between 1753 and 1774, chiefly in the first (1753) and second (1763) editions of Species Plantarum, and in later works such as Systema Naturae and Mantissa plantarum. Although Linnaeus showed much less interest in lichens than in flowering plants, he recognized their ecological role as pioneer organisms in primary ecological successions. Contrary to popular belief, he never referred to lichens as the ("the poorest peasants") or "poor trash of nature": that phrase was introduced by Georg Franz Hoffmann in 1787 and later misattributed to Linnaeus himself.
Of the roughly 2,000 lichen species now known from northern Europe, Linnaeus recognized only about 5% in his treatments. Most of his lichen names were based on material from northern Europe, especially Sweden, with only a handful of species described from specimens collected outside Europe. His lichen accounts were usually brief, consisting of short with few details of morphology, variation or ecology when judged against modern species descriptions. Even so, the Linnaean Herbarium at the Linnean Society of London contains 324 sheets with lichens and lichen-like organisms, although not all of these represent original material available to him at the time of publication.
Many of Linnaeus's lichen names are still in use today, though now placed in genera that did not exist in his time, and his species serve as the types for several important lichen genera including Cladonia, Lecidea, Lobaria, Parmelia, Peltigera, Ramalina and Usnea. At the same time, some of his species concepts were broad by modern standards. For example, his Lichen subfuscus and Lichen geographicus each correspond to species complexes that are now divided into several segregate taxa on morphological and molecular grounds. Other Linnaean names have been formally rejected or conserved with different types to preserve prevailing usage and stabilize nomenclature.
The typification and interpretation of Linnaean lichen names has therefore required sustained effort by lichenologists, involving critical study of his specimens, publications and other historical sources to determine the correct application of each name under the International Code of Nomenclature for algae, fungi, and plants. This list assembles all 110 Linnaean names that Linnaeus intended for lichens in the modern sense, regardless of their present status. For each original Linnaean name (the basionym), it records the original year of publication, the current taxonomic status or accepted name, and the year in which the present combination was published. In the "Basionym" column, author citations are omitted because all names in the list were originally published by Linnaeus (abbreviated "L."). The treatment largely follows the typifications and interpretations of Per Magnus Jørgensen, Peter Wilfred James and Charles Edward Jarvis published in 1994, supplemented by later taxonomic revisions and by current usage in major nomenclatural databases such as MycoBank and Index Fungorum.