Today at Ogden Reservoir, Calderdale. I haven’t seen it since the first winter it was found by Bruce Hoyle, and after great persistence on the part of Alison Galbraith, it was identified for us at Kew, how many years back I can’t remember. Two or three?

The barrier of old Christmas trees, where the Pithya grows on the dead Abies nordmannii between the perimeter path and the water, a way of disposing of them, while also preventing dogs entering the water and the shore, where birds can now breed without disturbance. (If they can tolerate the many walkers and dogs that pass close by.)