• Pertusaria lactea (L.) Arnold
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Pertusaria lactea
© Mike Simms
Pertusaria lactea
© Mike Simms
Pertusaria lactea
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This attractive white to ivory-grey, crustose lichen scattered with neat, white soralia is an attractive feature of damp but well-lit intermediate to mildly basic rocks of upland and coastal areas. Individual thalli of 15cm diam. or more can be seen growing on boulders along many of Irelandís upland stream courses. It is easily confirmed in the field by using fresh bleach as the thallus and soralia are C + rose red. It is also Pd -. It is mainly upland in Ireland and very rare in the interior and in the midlands.

Key characteristics

  • The immediate C+ red reaction confirms this species as distinct from other Pertusaria species. It could only be confused with P. aspergilla which tests C-, Pd + rust red
  • On well-illuminated rock, often in damp situations.

Original text submitted by Simon Davey

 Simms, M. J., (2016). Pertusaria lactea (L.) Arnold. [In] LichenIreland. Accessed on 2018-06-24.