Thallus foliose, green-grey or distinctly yellow-grey (but commonly appearing pure grey in digital photographs or with digital printing technology), lobes radiating, usually narrow and somewhat serpentine, often convex in cross-section or flattened at the tips, cracked and brown in the centre part of the thallus, with subglobose yellow to grey-yellow soralia on the lobe surfaces, lower surface black; apothecia small, with brown discs and pale, crenulate margins, said to be rare.

Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.

On exposed, base-poor rocks and gravestones, able to colonise various man-made surfaces.

All year round.

Widespread and locally common in Britain.

Widespread and quite common in Leicestershire and Rutland.