Lichen is derived from the Latin word Leichen meaning algae-like fungus. The new thallus formed by the coexistence of algae and fungi is called lichen. Lichens are called mitozoites.
In 1803, scientist Eric Acharius first described lichens and is considered the discoverer of lichens. Among the modern researchers, V. Ahmadjian has done the most research on lichens and is called the father of modern lichenology. 17,000 species of lichens of 400 genera have been found in the world and scientists estimate that their number will be 20,000.