Description: This common ‘scripture’ lichen has a smooth, crustose, pale grey thallus occupied by scores of small (1mm long), black, narrow discs (lirellae) each with a central slit. The discs grow together in dense clusters forming tight, circular colonies which can join to produce extensive mosaics. Widespread: smooth barked trees in hedgerows and woodland; also in churchyards and cemeteries.

Key Identification Features:

• Forms circular colonies of black, densely packed discs (a mixture of small black dots and straight or crooked lines)
• Mostly on smooth, shaded bark.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Arthonia atra at iNaturalist World Species Observations database.