• Buellia disciformis (Fr.) Mudd
Buellia disciformis
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Wherever there are smooth-barked trees, the trunk, branches and large twigs should be inspected for this ‘black and white’, crustose species. The rather thin, grey-yellow, mazy thallus bounded by a black line, scattered with near jet-black rounded discs (0.3-1.3mm diam.) are its chief attributes. Only in brightly-lit situations might it be confused with Lecidella elaeochroma var. elaeochroma. A squash of the discs under a microscope will show the brown one-septate spores perfectly in Buellia. A dab of Potassium hydroxide (K) gives a clear yellow reaction in B. disciformis compared with the Lecidella which is smudgy yellowish. It is common in the north and west, but largely absent from the south-east of Ireland.

Key characteristics

  • Greyish thallus scattered with groups of round, black discs bounded by a black margin
  • Smooth-bark lichen, K + yellow; spores brown, one-septate.

Original text submitted by Vince J. Giavarini

 Simms, M. J., (2016). Buellia disciformis (Fr.) Mudd. [In] LichenIreland. Accessed on 2018-07-22.