Monday, March 01, 2021

Lichens on twigs.

Today I spotted a small tuft of oakmoss, Evernia prunastri, one of the commonest and more easily identified lichens on a slender twig of the birch that I could just about reach.  Oakmoss is important in perfumery and has a large range of other uses.  One of its distinctive features is that the branches are paler underneath than on the upper side.

On looking at it under the microscope I noticed a much smaller greenish granular species dotted with dark fruit bodies.  It ran down to Fuscidea lightfootii in all my sources of information.  There were two further species on the small piece of twig I brought indoors: one with a very thin, greyish thallus and very few fruit bodies and another dark brown, very visceral-looking species that might be a Melanelixia.  The twigs were also heavily dusted with a green alga, probably a Desmococcus species.

The day after I discovered some beautifully patterned lichens on the smooth bark of the still standing pole of the dead ash.  These were readily identifiable as Arthonia radiata, another widespread species.  There was a second species with a very thin, grey and formless thallus scattered with rather few fruit bodies that will need further work to attempt an identification.  A good place to start with these is the Natural History Museum's publication Key to lichens on twigs.  This is also an online key A Key to Common Lichens on Twigs in the Key to Nature series: