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(Map updated: 11 August 2009)

Known by its popular name ‘blackberries and custard’, this has become one of Britain’s and Ireland’s most iconic lichens. This strongly oceanic, smooth-bark specialist has a yellow crustose thallus spotted with little black spherical discs (perithecia) that are arranged in tight constellations like small paw prints or blackberry clusters. Its association with smooth bark is very similar to that of other Pyrenula species. In western Ireland it is known from the Burren, and sites in Counties Kerry and Cork. In Ireland, it is largely confined to hazel but also occurs on holly in old, relict woodlands.

Key characteristics

• Can be separated from other Pyrenula species by the paw-print arrangement of the discs and the large muriform spores (section the discs to see)
• Only on hazel and holly; when wet, the thallus appears to swell the girth of branches giving the appearance of blackberries floating on custard.

Original text submitted by Vince J. Giavarini