whitish, greenish gray, or bluish gray, thin, sorediate, smooth, or verruculose. Apothecia
broadly adnate; margin
of same color, disappearing; exciple
hyphae radiate, orange, also K+ violet, granular-inspersed; disk
flat becoming depressed convex, bare, orange-red; hypothecium
hyaline to brownish; epihymenium
orange-red, K+ violet; hymenium
65-75 μm, hyaline, upper part inspersed with yellow granules, 1+ blue; paraphyses coherent, not branched, tips not thickened; asci clavate; spores oblong to ellipsoid, 8-12 x 2-4 μm.
Reactions: thallus K+ yellow, C—, P+ red.
Contents: atranorin(in apothecia), fumarprotocetraric acid, especially in the soredia, and an anthraquinone pigment.
This species grows on a variety of trees, including Abies, Picea, Larix, Pseudotsuga, Pinus, and Betula. It occurs in Europe, Greenland, and North America. In the latter, I. M. Brodo informs me that, while fruiting in the West, it also occurs commonly as a sterile lichen in the East, where he has records from New Brunswick, Nova Scotia, Quebec, Newfoundland, Ontario, and Manitoba. Only fruiting specimens are represented in the distribution map.
The collections by J. Vahl on Betula at Tunug-dliarfik in the Julianehaab district were checked by Lynge (1940), who interestingly mentioned that he “would refer this species to Protoblastenia, ” a disposition mentioned also by current authors as a possibility based on the K+ reaction of the epihymenium.