Cetraria pinastri (Scop.) Gray = Vulpicida pinastri (Scop.) J.E. Mattsson & M.J. Lai

      Foliose thallus formed of lobes arranged more or less in a rosette, 2-4 cm in diameter, with erect, rounded and undulating ends, upper surface yellow in the sun, yellowish grey-green, pale lemon grey in the shade, margin bordered by floury to granular soredia arranged in a ridge, bright lemon yellow; lower surface concolorous but paler, with pale brown rhizines, yellow medulla. Apothecia extremely rare, lecanorine, brown disc, smooth thalline margin. Ascospores simple, colorless, subglobose, 5-6 µm in diameter. Cortex: K-, C-, KC+ yellow, P-, medulla: K-, C-, KC-, P-, UV+ dark red. Contains toxic vulpinic acid. Arctic, boreal, and alpine corticolous and lignicolous (very rarely saxicolous) species found at the base of trunks or lower branches of trees, particularly conifers, in areas where snow persists for long periods.

N.B. Species often associated with Parmeliopsis ambigua in Europe and Parmeliopsis capitata in North America (see photographs).