Caloplaca flavorubescens. One of my greater lichen triumphs was to find this species on a old, but not very large ash tree in Parham Park, West Sussex. It had been extinct in England for several years. Caloplaca species on trees are not common in any case. This species has a pale thallus, and attractive bright orange apothecia. Since it was found, it has been increasing on the tree. The even darker apothecium above the C. flavorybescens is another species on this tree, Caloplaca ulcerosa, the next species to be dealt with.