within the bark or over it, very thin to thin, smooth or slightly tuberculate, dull or shiny, ashy gray or green-gray to yellow-green, continuous to chinky but not areolate, lacking soredia or isidia. Fertile verrucae with broad disk sessile or immersed in thallus; disks
pink or red, epruinose, to 0.6 mm broad, soon rupturing the verruca and becoming high convex, the margin stellate or lobate, at first covering the disk but then occluded by it when erumpent. Apothecia
1 per verruca, to 0.76 mm; hypothecium
hyaline, K-; hymenium
hyaline to pink; asci
clavate or cylindrical; spores
8, biseri-ate or uniseriate, ellipsoid to fusiform, the single wall 2-5 µm thick, tips often thickening, convex inward, end wall 5-10 µm, 16-42 x 10-18 µm.
Reactions: cortex K-, C—, KC-, P—; medulla K-, C+ red, KC+ red, P-.
Contents: gyrophoric acid (sometimes scant).
This species grows on smooth-barked hardwoods and sometimes on conifers. It is apparently circumpolar boreal but is seldom recorded in North America.