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Stereocaulon groenlandicum (E. Dahl) Lamb
Family: Stereocaulaceae
Stereocaulon groenlandicum image
Stephen Sharnoff  
Thompson, J., 1984. American Arctic Lichens: The Macrolichens.
Pseudopodetia erect or prostrate, firmly attached to rocks or soil, rigid and woody (like S. botryosum) 1.5-5 cm tall, to 2 mm thick, terete, sparingly branched, sometimes more or less corymbose; whitish, dull, decorticate, smooth to longitudinally striate, with pale tomentum which may be browner toward the base; phyllocladia whitish, grain-like, becoming thickly crenate or digitate squamuliform, occasionally lobed and branching like those of S. rivulorum, lacking soredia; cephalodia inconspicuous, sometimes lacking, among the phyllocladia, subglobular, usually pale brownish or yellowish, when well developed with slightly tuberculate appearance, the units with dark central spots, containing Nostoc. Apothecia large, to 3-6 mm, becoming compound, dark brown to black brown, terminal on branches, exciple soon disappearing, palisade-radiate; hypothecium hyaline to cloudy; hymenium 50-75 asci 50-60 µ; spores 4-8, elongate fusiform, straight, 3-septate, 20-40 X 3-4 µ.

Reactions: K+ yellow, PD+ pale yellow.

Contents: atranorin, miriquidic acid, perlatolic acid, and anziaic acid (Lamb 1973).

This species is known from rocks and gravels in Scandinavia, Greenland, Alaska, and an uncertain record from Spitzbergen. Lamb (1977) states that it occurs also in the Northwest Territories but cites no localities in that paper. This species is very close to S. rivulorum, differing in the more woody pseudo-podetium and the presence of miriquidic acid. The other contents are similar to those of strain I of S. rivulorum.