Just about everyone has noticed crusty, scale-like growths (crustose) or leafy growths (foliose) on rocks, trees and even bare ground called Lichens. But few know that Lichens are not just one organism, but a composite made up of two or more living elements. For over 150 years scientists have known that Lichens are composed of algae and fungi, beneficially living together (symbiosis). Recent studies suggest that a third partner, yeast, is another element. Lichens are not parasites, they don’t harm the trees or plants on which they grow. On Alligator River Refuge most Lichen growth is found on tree trunks and branches. Below, the top photo is of a foliose Lichen. Bottom photo is a crustose Lichen. There are also squamulose and fruticose Lichens not shown.