Teloschistaceae Caloplaca ulcerosa Growth type crustose Chemical results: Thallus and soredia K-, apothecia K+ crimson Identification: Bryan Edwards, Vince Giavarini Scarce, on nutrient enriched base-rich bark of well-lit, mature trunks. Most frequent on Elm, Sycamore and Ash. Thin greyish-white thallus with grey to pale yellow-green soralia bursting from blister-like craters. Scattered apothecia with bright orange discs, margins becoming excluded. Spores 8-12 x 4-8 µm, septum 3-6 µm wide. Paraphyses with swollen tips. Microscope photograph below. The yellow apothecia in the photographs are Caloplaca phlogina

Microscope photograph

Caloplaca ulcerosa
On Ash. Upton Park and Holton Lee, Dorset. January and March 2013