Punctelia subrudecta

Punctelia subrudecta is a species of foliose lichen in the family Parmeliaceae. Originally described in 1886 as Parmelia subrudecta, it was transferred to the genus Punctelia in 1982. For much of the twentieth century, North American specimens were misidentified as this species, until molecular phylogenetics studies in 2010 revealed that they represented three distinct species, restricting the true P. subrudecta to Old World populations. The lichen forms loosely attached rosettes with narrow, pale grey-green lobes and is distinguished by its pale underside, fine powdery reproductive structures (soredia), and distinctive hook-shaped conidia. It is found primarily in temperate and Mediterranean woodlands of Europe, Macaronesia, and parts of North and East Africa, where it grows on tree bark and occasionally on rock surfaces....read more on Wikipedia.