Description: This is one of the commonest lichens of calcareous stone and walls in almost all areas of the country. It can be recognised by a combination of chocolate-brown to black-coloured thallus and minutely cracked surface. The shiny, globose discs (perithecia) resemble tiny, black beads and lie half-immersed in the thallus. It is easily overlooked as a black stain or smear. Calcareous rock, concrete and mortar; rare on siliceous stone.

Key Identification Features:

• Chocolate-brown to black thallus with cracks dividing the surface into a maze like mud on the bottom of a dried-up pond
• Globose, shiny black, half-sunken discs.

Original text submitted by Vince J. Giavarini

Distribution Map from NBN: Verrucaria nigrescens at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Verrucaria nigrescens at iNaturalist World Species Observations database.