DESCRIPTION: Foliose.  A common leafy lichen that is easily misidentified if care is not taken.  The lobes are fairly rounded and overlapping with a silvery-grey-green appearance to the upperside.  Marginal cilia are common and linear marginal soredia are best seen on the margins of mature lobes. The undersurface is black with rhizines at the centre and the margins are tan-coloured and without rhizines. Chemical results:- Medulla and soralia K+ yellow, KC+ yellow-orange, P+ yellow-orange. DISTRIBUTION: Widespread in the south and west and locally frequent elsewhere except certain areas of Scotland where it is absent. HABITAT: Usually found on the bark of a variety of trees but also recorded on rock and bare ground.