There are a lot of patches of lichen on my tree bark, and on googling I find Xanthoria parietina is a foliose, or leafy, lichen. It has wide distribution, and many common names such as common orange lichen, yellow scale, maritime sunburst lichen and shore lichen. It can be found near the shore on rocks or walls (hence the epithet parietina meaning “on walls”), and also on inland rocks, walls, or tree bark. It was chosen as a Model organism for genomic sequencing (planned in 2006) by the US Department of Energy Joint Genome Institute(JGI). In the past it was used as a remedy for jaundice because of its yellow color.
You learn something new every day..as they say.