Family: Caliciaceae Species: Buellia griseovirens Growth type crustose. Identifications by Brian Coppins and Andy Acton. Photos: On wooden bridge and Rhododendron. Co. Cork, SW Ireland Variable. The greyish thallus can be thick or thin, smooth, wrinkled or cracked, sometimes with greyish-black prothallus. Usually sterile with scattered bluish grey-green soralia (scratching yellowish) which can become confluent, +/- covering thallus. Apothecia are very rare, black discs with brownish epithecium. Thallus and soralia: K+ yellow going red, C+/- yellow, KC-, P+ yellow, UV- Tolerates moderate pollution. Occurs on well-lit, +/- smooth bark and worked timber, rare on brick. Similar: Mycoblastus caesius and Xylographa vitiligo

Buellia griseovirens January and March 2010