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(Map updated: 11 August 2009)

P. britannica is a very uncommon, large, foliose species with rounded, wavy, bright-green lobes when wet and upper surface scattered with small, dark, flat or slightly concave scabs (cephalodia), with free margins sometimes detaching to leave white scars. In size and colour when wet it closely resembles P. leucophlebia (described elsewhere), which has its cephalodia clamped down (limpet-like) and lobes with a network of dark veins below. Note: In P. britannica the veining below is either vague or absent. It grows on mossy rocks and walls in damp, sheltered woodlands and is thinly scattered in northern, eastern and western Ireland.

Key characteristics

• Large lobed ‘dog lichen’, bright green when wet with upper side featuring scattered, scab-like cephalodia that are loosely attached with raised margins
• Undersurface lacking network of dark veins; damp mossy rocks in woodland.

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