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(Map updated: 11 August 2009)

This striking yellow-green lichen is a common sight on shaded siliceous rocks, for example, sandstones, and the shaded brickwork of old buildings. It is relatively insensitive to industrial pollution. It consists of a powdery crust often spreading extensively over the substrate. It is occasionally fertile, with rather pale, small, yellowish-beige discs. Under a UV lamp it is dull to bright orange which helps to separate it from some similarly coloured sterile species.

Key characteristics

• The yellow-green, powdery thallus is distinctive, especially when growing on headstones in local churchyards and cemeteries
• Dry, shady situations are ideal conditions for it.

Original text submitted by Simon Davey