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© Mike Simms

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(Map updated: 11 August 2009)

This crustose epiphyte is a familiar ‘dry-side’ species. Old, smooth bark, especially beech and sycamore can support vast patches of it. The thin, cracked, brown-grey thallus, often with a hint of mauve, is easily overlooked as bark, but look closer and the surface will be seen to be covered in a pale brown felt of powder (soredia). Discs are very rare. Look for it on the bark of old, mature trees where it will be well developed. It can also be found on young trees. It may be commoner in the east of Ireland.

Key characteristics

• On the dry side of old or mature trees; brown-grey thallus minutely covered with a fine speckling of slightly darker powder (soredia)
• It can be separated from other species with a similar appearance by scratching with a fingernail. As the algal partner is Trentepohlia, the scratched surface will appear golden.

Original text submitted by Simon Davey