A foliose species with a grey, orbicular thallus that attaches closely to the substratum. It consists of nearly smooth, rounded lobes that are sprinkled with delimited soredia that arise from white, punctiform pseudocyplellae. The under surface is light brown to white, but darker in the centre, and has simple rhizines.
Cortex: K+ yellow. Medulla: C+ red, K-, UV-
In Scotland, Punctelia subrudecta has a limited, and mainly lowland, distribution. It can be found on well-lit, broadleaved trees and amongst mosses on siliceous rocks. BLS distribution map
scottishlichens.co.uk 