Flavoplaca calcitrapa 1.jpg
Flavoplaca (Caloplaca) calcitrapa, a squash preparation of a portion of the hymenium mounted in potassium hydroxide. Specimen collected from balustrade at Cliveden, Buckinghamshire. This micrograph was taken before the identity of the specimen was known and it was the distinctive spores which raised suspicion that this could be a significant discovery. The spores are seen to be thick-walled with hour glass lumina. This spore type is known in only two European species of the Caloplaca group: the normally Mediterranean F. calcitrapa and F. dichroa which differs morphologically in being blastidiate.