In reply to drolex:
> ....
> I read recently that lichens grow an inch in diameter every century (or something to that effect) and that the big ones (dish size) could have seen Richard III. ...
This is an oft-quoted factoid, but not really true. How come you get big colonies of lichens on the top of fence posts? On dry stone walls?
It's because they are very diverse, some do spread slowly over hundreds of years but by no means all of them.
As you say, they are really interesting things, although most peoples eyes glaze over when I go on about them.
I'm just in the process of trying to get something in the guide for Shaftoe about a one, charmingly known as Rock Tripe, which is common as muck in mountain environments, but rare in Northumberland (2 known sites) and the flipping thing is growing along just above the lip of one of the traverses