blue-gray rosette lichen lichen growing on a tree trunk.

aged atmosphere autumn background bark bluegray brown caesia close closeup colloquially dark dirty element exterior foliose forest fungus graywhite growing grungy known landscape lichen lichenized lichens macro material natural nature old outdoors physcia powderback rosette rough scenery scenic skin snowflakes species summer surface symbiosis terrain texture textured trail travel tree trees trunk white wilderness wood