Description: This crustose species is mostly characteristic of old wooden fencing and twigs and branches of acid-barked trees. The thallus is usually sterile (without discs), grey, and is covered with ulcer-like dark green to blue-green soralia. Owing to the nature of the climate, the interior of Ireland has its field boundaries rarely fashioned from wood so weather-worn worked timber is in short supply. Picnic tables are today one of the best alternative habitats for it. B. griseovirens turns K+yellow to red. It is a much overlooked species.

Key Identification Features:

• The grey, sterile thallus and scattered blue-green soredia reacting K+yellow to red should confirm it
• It is most likely to be confused with Trapeliopsis flexuosa which is C+ red.

Original text submitted by Simon Davey

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

iNaturalist: Buellia griseovirens at iNaturalist World Species Observations database.