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Lichen: Parmelia saxatilis

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Parmelia saxalitis - thalline edge.

Parmelia saxatilis

Name: Parmelia saxatilis (L.) Ach.

Pronunciation: Parmelia saxatilis

Conservation Evaluation: Least Concern

Popular Name: Shield Lichen Body Type: Foliose

Paramelia saxatilis apothecia.

Description: The silver-grey thallus can grow to diameters of 30 cm. The growths are generally circular and undulating and brown towards the tips of the lobes. It is distinguished from other Parmelia by the white network of veins (pseudocyphellae) and the profusion of granular dots of isidia on the upper surface.

The underside is black and has a ‘furry’ texture due to the abundance of simple rhizines; it is also lighter in colour towards the edges. Apothecia are rare (see the photos). Ascus contains 16 to 18 spores.

Parmelia saxatilis - specimen on wood.

Chemical Tests: Cortex is K +– orange turning red.

map-parmelia-saxatilis

Nature Notes: This is a common species in Ireland, growing on stone walls and rocks, particularly in the West where it prefers oceanic areas.

Vice County distribution map of Parmelia saxatilis: See Map

Link: Map this species on the Lichen Survey

Other species recorded in Ireland

  • Parmelia discordans Nyl.
  • Parmelia omphalodes (L.) Ach.
  • Parmelia sulcata Taylor

Text and images © Paul Whelan, 2009.