Order: Peltigerales Family: Collemataceae
Species: Collema cristatum
Photos: On limestone in the Burren and on wall, Foynes.
Co. Clare and Co. Limerick, Ireland. Identification needs confirming
Round, semi-circular or irregular thallus, centre often disintergrating with age. Lobes thinnish, radiating, convoluted, margins wavy, entire or incised. Upper surface dark olive-green to black, lower with white tufts of hapters. Sessile or stalked apothecia with even margins, usually crowded, +/- marginal, sometimes absent.
Common throughout Ireland on hard calcareous rocks, mortar and tombstones. Chemical reactions negative.
Collema cristatum. July 2009