Rhizocarpaceae Rhizocarpon reductum Growth type crustose Chemical reactions variable, usually K+ yellow, C-, P+ orange. Rarely K-, P- or K+ red, P+ orange Pioneer species on siliceous pebbles, rocks and tombstones. Grey to mousey-brown thallus, cracked-areolate with a thin black prothallus. The black apothecia become seesile with thin, persistent margins. Epithecium dark green to greyish-brown. Spores colourless, becoming muriform with 8-13 cells, 20-35 x 10-15 µm. Micro photos below. Similar: Rhizocarpon petraeum

Microscope photographs



Rhizocarpon reductum
On pebbles and gravestone. Studland and Lytchett Matravers, Dorset. March 2013, December 2016