Really pleased to find this. Found it on a twig from a Quercus robur in the ground. This lichen was named after William Borrer, the Henfield naturalist who made the first scientific study of it in early 19th century. It’s only found in the far south. It is very similar to P. jackeri & P. subredecta. It is identified by (a) its abundant tiny pseudocyphellae – tiny white holes in the thallus (body) for gas exchange, (b) white fluffy lumps, which are soredia (vegetative propagules of fungi hyphae and algal photobiont), coming out of soralia (structures that produces the soredia) and (c) pale tipped rhyzines (structures that fix the lichen to its substrate). New hectad record for the British Lichen Society.
Sim's Nature Notes 