LichenIreland
  • Pertusaria amara (Ach.) Nyl.
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Pertusaria amara
© Robert Thompson
Pertusaria amara
© Robert Thompson
Pertusaria amara
© Robert Thompson
Pertusaria amara
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(Map updated: 11 August 2009)
Pertusaria amara
© Mike Simms
Pertusaria amara
© Mike Simms
 

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This crustose lichen has a thin to thick, grey coloured thallus scattered with white, finely-granular soredia which stands out from the surface like a white rash. This is the only lichen for which taste can be used as a means of certain identification. Wet a finger against the soredia and dab on the tongue; then wait a second or two. The bitter taste is oxalic acid. The absence of a bitter taste suggests you may have encountered a lookalike species, P. albescens. Even the most experienced lichenologists trust the taste test. Beginners trying it out for the first time soon learn that only a few grains of soredia is all that is required to achieve a successful outcome. Common: acid-barked trees such as oak and beech, rarer on rock.

Key characteristics

  • Scattered white soredia on a grey thallus
  • Taste-test for oxalic acid a must, for certain identification.

Original text submitted by Vince J. Giavarini

 Simms, M. J., (2016). Pertusaria amara (Ach.) Nyl.. [In] LichenIreland.
http://www.habitas.org.uk/lichenireland/species.asp?item=19378 Accessed on 2017-10-21.