Old Man's Beard

I have been meaning to blip this for a while - there is a veritable forest of this on a tree by our back door and when the leaves are off it makes a striking feature.

Most people know it as "Old Man's Beard" and I have always been told that it is a good bioindicator, as it only flourishes where the air is clean.   It certainly flourishes in Argyll but on looking it up today I was surprised to discover that it is not only global in its reach but that there are perhaps as many as 600 species of Usnea, to give it its proper name.