A foliose species with a light pearl-grey, orbicular thallus that consists of ascending lobes that are smooth towards the edges but more distinctively wrinkled centrally. The margins are incised and undulating, and occasionally carry forked black cilia. The marginal soralia cause the lobe margins to roll back.
Cortex: K+ yellow. Medulla: C-, K+ yellow, UV-
In Scotland, Parmotrema perlatum is widespread in the west, but much less frequent in the east where it has a coastal distribution further north. It is found on well-lit, neutral to somewhat acid-barked, broadleaved trees and on siliceous rocks. BLS distribution map
scottishlichens.co.uk 