a multicolored lichen usnea hangs on a birch branch in a wild forest.

alga algae altitude anchored ascomycota asexual barbata barbate beard beardlichen biology botany branch chlorophyta covered dead ecology fir forest fructicose fungus green hang indigenous jungle lichen life moss natural nature outdoor parasite park parmeliaceae pine pinewood shrub soft still symbiosis symbol tree trunk usnea usneabarbata vegetation white wild wilderness wood