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(Map updated: 11 August 2009)

This true aquatic lichen with thick, foliose, tongue-like lobes (to 1cm wide) can be found growing in loose bundles on rocks and boulders in clean, usually fast-flowing rivers and streams. Though grey when dry, the thallus becomes emerald green when wet which is useful in distinguishing it from other members of the same family. It occurs in the zone just above the ‘submerged’ which means it is usually at, or just above or below, the waterline. It is scattered in suitable habitat in Ireland.

Key characteristics

• The emerald green, rounded, foliose thallus when submerged helps to indicate this species. It is beige coloured when dry
• All other aquatic species of Dermatocarpon are relatively unchanged when submerged.

NBN Atlas mapping: Species account : NBN Atlas UK Species Observations database

iNaturalist: Species account : iNaturalist World Species Observations database

Original text submitted by Simon Davey