• Rhizocarpon umbilicatum (Ramond) Flagey
Rhizocarpon umbilicatum
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This crustose lichen is very similar in appearance to R. petraeum (described elsewhere) which is also grey-white coloured. It lacks the concentric rings formed by the discs of that species and has a much thicker, chalky grey not pale grey-white thallus. The discs of R. umbilicatum are randomly scattered. R. umbilicatum grows on pure limestones, R. concentricum on rocks of a more intermediate nature. Throughout Ireland.

Key characteristics

  • The discs are randomly scattered about the thallus, that is, they do not grow in concentric rings
  • The thallus colour is chalky white or chalk-grey and grows on pure limestones.

Original text submitted by Vince J. Giavarini

 Simms, M. J., (2016). Rhizocarpon umbilicatum (Ramond) Flagey. [In] LichenIreland. Accessed on 2018-07-19.