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(Map updated: 11 August 2009)

This ‘bark-pimple’ lichen grows exclusively on birch. There is no visible thallus so the tiny, black, spherical discs (0.3-0.5mm diam.) show up as black dots on the bark often with a faint, dark shadow below the disc. From above the discs (perithecia) appear oval. The spores are colourless, curved and one-septate (25-35 x 2-4ųm). Scattered; Northern and western Ireland.

Key characteristics

• Grows only on birch bark; discs are black perithecia which dot the bark as tiny ovals
• Thallus absent; spores colourless, curved, one-septate when mature.

Original text submitted by Vince J. Giavarini