Melanohalea exasperata Warty Brown-shield

A foliose lichen found growing on the well-lit twigs and branches of more acid-barked deciduous trees. The thallus is olive-green when wet, becoming brown when dry, and is covered with warts with pale-tipped craters. The brown apothecia have thick, warted margins and produce simple spores, 9-12 x 5-6 µm. 

Host to Abrothallus bertianus

Listed under Parmelia exasperata by Alan Orange in Flora of Glamorgan (Wade et al, 1994).