Identify the Symbiosis

Lichens grows on trees. They grow on maple trees and many more trees. There is like all the trees in the world that Lichens grow on. A simple slow-growing plant that typically forms a low crust like, leaflike, or branching growth on rocks, walls, and trees. It is also a skin disease in which small pimples or bumps occur close together. Thanks for reading by Derrick Bronzynski.