April 7, 2008:
A visit to see this interesting lichen. Lobaria virens is an epiphyte which attaches itself to tree bark and whose presence is a classic indicator of ancient woodland. In the British Isles it has a westerly, oceanic distribution and is nowadays mainly found in south-west England, Cumbria, western Scotland, and Ireland. Everywhere however it is scarce or very scarce and is particularly susceptible to atmospheric pollution, especially sulphur dioxide.
It is found on the more acidic-barked trees such as oak and ash. When growing on trees which have become isolated due to woodland felling it may dry out and die off. Lobaria virens also occurs in Scandinavia and in western and southern Europe.
Below, the fruiting bodies (apothecia) can be seen as prominent, slightly concave brown discs.
Below, the small volcano-like protuberances are incipient apothecia which will develop similar to those shown above.
A Cumbrian oak with a large thallus of Lobaria virens. Towards the bottom left of the trunk the related Lobaria pulmonaria can just be seen.
I'm grateful to Mike Porter whose eagle-eye and persistence located the tree and both to him and to Jeremy Roberts for discussions about Lobaria virens.