Rhizocarpaceae Rhizocarpon subgeminatum Growth type crustose. BLS conservation evaluation: LC NS Chemical results negative. Epithecium olive-green, K- (intensifying green) Infrequent (but probably under-recorded) on +/- nutrient-enriched siliceous rocks. Photographs below on slate roof tiles. Areolate pale to dark brown thallus, the areoles small (to 1mm diam), scattered or contiguous. Black, non-pruinose apothecia, the asci 1-2(-4) spored, spores muriform, 30-50 x 20-28 µm, persistently colourless or becoming slightly green with age. Micrographs below. Similar: R. geminatum, epithecium K+ purple-red, spores dark green-brown

Micrographs





Rhizocarpon subgeminatum
Photographs: Wimborne, Dorset. November 2014