Parmelia fertilis

Parmelia fertilis is a species of corticolous (bark-dwelling) foliose lichen in the family Parmeliaceae. Originally described from Siberian collections in 1887, this lichen has a broad temperate distribution across the Northern Hemisphere, occurring in Asia from the Himalayas to Japan and Taiwan, in Siberia, and in maritime regions of eastern Canada. In North America it was recognised only late in the 20th century and has since been confirmed from Maine, where it was first reported for the United States. The species forms pale greenish to whitish-grey rosette-shaped growths 6–12 cm across on tree bark, characterized by lobes with conspicuous pale pores that sometimes merge into a white network near the tips. It is closely related to Parmelia sulcata but can be distinguished by its smaller asexual spores and denser root-like structures on the undersurface, and it readily produces fruiting bodies....read more on Wikipedia.