Umbilicaria isidiosa

Umbilicaria isidiosa is a species of foliose lichen belonging to the family Umbilicariaceae. It is endemic to Bolivia, where it occurs in high-altitude regions of the Bolivian Andes. It is distinguished by its thallus, which has an upper surface ranging from ashy brown to mouse grey, featuring a frosty (pruinose) texture that varies from smooth to slightly rough. This surface is adorned with numerous isidia (reproductive propagules), ranging from spherical to richly branched, primarily concentrated along the margins. The lower surface is dark, transitioning from smooth to rough in texture, and sparsely covered with dark rhizines (root-like structures)....read more on Wikipedia.