Caloplaca albolutescens. A species which was not acceptable to British lichenologists until quite recently, but has been acceptable to the Dutch. It has a characteristic grey, and isidiate thallus with fairly large, and attractive apothecia. This photograph was of a specimen shown to me by the Dutch lichenologist Andre Aptroot in the grounds of Kew Church. It is a species occurring on limestone, and especially artifical calcareous habitats. It is said to be readily confused with Caloplaca teicholyta, which is only very rarely fertile. My experience of it is that it is rather distinctive.