Thompson, J., 1984. American Arctic Lichens: The Macrolichens.
Thallus squamulose or partly areolate-squamulose, the squamules 0.2-2 mm long, 0.2-0.7 mm broad, flat or partly convex, ascending or adnate, more or less sorediate with labriform soralia, whitish or ashy, the margin crenulate, underside whitish, occasionally rhizinose. Apothecia to 2 mm broad, solitary or clustered, sessile or subsessile to long-stipitate, the stipes to 5 mm tall and furrowed; disk flat to more commonly convex, the edges sometimes reflexed, reddish brown, sometimes slightly pruinose, the pale margin disappearing; cortex of thallus variable, partly of vertical paraplec-tenchyma, partly of hyphae fanning out from between the algal glomerules and becoming interwoven, and partly forming a vertical decomposed layer, the hyphae leptodermatous, 1.7-2.2 μ in diameter; stipes solid, the hyphae pachydermatous, 4 μ in diameter, algae present to below the apothecium; epithecium brownish; exciple poorly developed, thin, pale; hypothecium to 100 μ thick, brownish; hymenium hyaline or brownish, 70-100 μ; paraphyses lax, slender, 1-3 μ thick, slightly branched at the tips, the tips scarcely thickened; asci cylindrical, 60-75 x 5-8 μ; spores 8, uniserate or the apical ones biseriate, spindle shaped, simple or 1-septate, hyaline, 3-11 x 2-2.75 μ.
Reactions: K+ yellow turning red, P + yellow to orange.
Contents: norstictic acid.
This species grows on soils high in clays, especially on frost boils in the Arctic. It is not only in the coniferous forest but also in the tundras further north.
This species is circumpolar and boreal to arctic but is also found in the West Indies, the Philippines, Hawaii, and New Zealand.