Crottle (Crotal=lichen in Gaelic). Parmelia saxatilis
A foliose lichen, pale grey above having a bronze-pinkish tinge (often when a fungal infection is present). The underside is black.
Small individual lobes, several mm across typically surround a large detachable isidium. The many grey-brown rod-like isidia form the vegetative propagules. Sexual apothecia occur infrequently.
Like Punctellia (illustrated last month) it grows on acid media eg oak-bark, siliceous rocks or as here on stone walls. It has grown on human bones Dobson F notes when on the skull of a hanged man it allegedly has special medicinal properties. It is intolerant of nitrogen pollution and enrichment.
An important past use was as a red-brown wool dye.
RR Photographed this Jersey Tiger Moth in his back garden in Sawbridgeworth. They used to be restricted to southern Britain but with the advent of global warming they seem to be spreading northwards.
RR had seen some 'woolly bears' a short while ago and this may well have hatched from one of those.
JF Has returned to Rowney Wood which we visited to look for spring flowers early in the summer programme. He was fortunate to see several Purple Emperor butterfly's 'jousting' high in the canopy and then later on finding this splendid specimen sunbathing on one of the paths.