Black lichen on limestone

Black lichen on limestone

Observation - Black lichen on limestone - UK and Ireland. Description: Black crustose lichen patch about 15cm across growing on angled limestone ledge on north facing church wall. Dark blue prothallus visible in picture (i). Flat, shiny, black apothecia. Possibly Placynthium nigrum.

Black crustose lichen patch about 15cm across growing on angled limestone ledge on north facing church wall. Dark blue prothallus visible in picture (i). Flat, shiny, black apothecia. Possibly Placynthium nigrum.