Species: Collema furfuraceum
Photos: On Sycamore trunk and coastal rocks. Cork, SW Ireland.
Specimens confirmed by J Douglass
Black or dark-brownish lobes with conspicuous longitudinal ridges on the upper surface. Dense patches of simple or branched isidea can spread over the whole upper surface. Apothecia are very rare.
Found on coastal rocks and trunks of well-lit deciduous trees.
Chemical reactions negative.
Collema furfuraceum. January and November 2009