• Verrucaria dufourii DC.
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Verrucaria dufourii
© Mike Simms
Verrucaria dufourii
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(Map updated: 11 August 2009)

This is lichen of hard, horizontal natural limestone, abundant in places like The Burren but also on limestone tombs in some of the older churchyards. The majority of the thallus — apart from specks of pale grey or fawn-grey, is buried in the rock with only the spherical discs visible (0.3-0.5mm diam.). These have a ‘sucked-in’ apex like little rubber tyres, showing clearly from above. Between the constellations of discs, black dots (pycnidia) may often be seen. Throughout Ireland; rare in the extreme south-east.

Key characteristics

  • Thallus immersed, discs and dots (pycnidia) visible at the surface, speckled with fragments of grey or brown from below
  • Discs with distinct sunken apex; hard limestone.

Original text submitted by Vince J. Giavarini

 Simms, M. J., (2016). Verrucaria dufourii DC.. [In] LichenIreland. Accessed on 2019-08-25.