Order: Lecanorales       Family: Physciaceae Species: Buellia griseovirens Growth type crustose. Photos: On wooden bridge and Rhododendron trunk. Co. Cork, SW Ireland. Identifications by Brian Coppins and Andy Acton. 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