Foliose lichen growing on a tree branch.
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
No interactions present.
What species of tree is that?
I think that what the lichen is on is a fallen branch of something.
What the leaves are is an interesting question. When I named the lichen I assumed the leaves were Japanese Knotweed (Fallopia japonica). However, looking at it again, it might be a hybrid, "Conolly's Knotweed", Fallopia x bohemica. The leaves look a little long for F. japonica. But it is difficult to tell from the photograph.
Lat/Lng: 51.5, -3.6
OS grid ref: SS8983