Geograph - photograph every grid square

Apart from moss, most of the image is taken up by the lichen referred to in the title. It has grey-green lobes; on those at the edge, there is a network of paler lines, pseudocyphellae, areas where the outer layer (cortex) is thinner. The more central parts of the lichen are densely covered with tiny rod-shaped structures called isidia; these break off, allowing the lichen to spread vegetatively (asexually).

Less common are the prominent discs that can be seen near the centre of the picture. These are apothecia, the spore-producing discs. As can be seen by looking closely at the picture, the margins of the discs also have, in this case, isidia on them.

This is a common species, and the features visible in this image correspond well with the description given in "The Lichen Flora of Great Britain and Ireland" (Purvis, etc.; 1992). For example, that book says of the spore-producing discs: "apothecia to 1cm diameter, occasional; disc red-brown to dark brown, often isidiate at margin".

The lichen shown here was growing on the rock face shown in NS4280 : Looking along a smooth rock face; the setting is in fact an NS4280 : Old quarry pit.

The multiply-branched structures at the top edge and in the lower half of the picture belong to different lichen species (genus Cladonia).