Description: Formerly subsumed under the heading of Caloplaca citrina agg., this species is a familiar sight on calcareous walls, mortar and limestone rock. The body of the lichen is visible as a granular orange crust cracked into islands (areoles) of thallus. Discs are common with spores thick-walled when young. There is a yellow colour form and occasionally the two forms occur side by side. The very small granules (blastidia) are sparingly sorediate. In Ireland, this species is probably widely under-recorded.

Key Identification Features:

• Thallus: small, minutely granular orange or yellow, cracked into areoles
• The tiny blastidia slowly break down into soredia; internally, the spores show hourglass configuration.

Original text submitted by Vince J. Giavarini

Distribution Map from NBN: Flavoplaca dichroa at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Flavoplaca dichroa at iNaturalist World Species Observations database.