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(Map updated: 11 August 2009)

After rain, the thallus of this ‘dog lichen’ which turns bright green can be a glorious sight. It grows mainly among the short grassy banks of upland streams and rivers, especially those running over calcareous rocks. Attached to the upper surface of the thallus are brown warts or cephalodia which clamp down like limpets and can be difficult to dislodge. P. britannica is similar in colour when wet but differs in habitat and in the looser cephalodia with free edges that are easy to remove. In Ireland, the best sites for it are in Counties Clare and Sligo.

Key characteristics

• Thallus a beautiful bright green when wet
• Upper surface with cephalodia which are tightly attached with no free edges.

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

iNaturalist: Species account : iNaturalist World Species Observations database

Original text submitted by Vince J. Giavarini