colorful lichens, greyish brown lichen physcia stellaris growing on a branch of tree

apothecia background bacteria bark beautiful biology branch brown close closeup color colorful colourful cyanobacterium detail disease ecosystem environment flora foliose forest fungi fungus gray greyish grow growing growth lichen lichenes lichens macro moss mossy mushroom natural nature oak old parietina pattern physcia stellaris stone surface texture textured tree trunk wood wooden xanthoria yellow