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Stereocaulon arenarium (Savicz) Lamb
Family: Stereocaulaceae
Stereocaulon arenarium image
Stephen Sharnoff  
Thompson, J., 1984. American Arctic Lichens: The Macrolichens.
Pseudopodetia in compact clumps, densely caespitose, loosely or firmly attached, 1-3 cm tall, brownish, bare and dead below, tomentose above simple to sparingly irregularly branched; phyllocladia nodulose or verrucose to flattened peltate, olive bluish or yellowish centrally, paler at the margins, esorediate; cephalodia scarce to frequent, on the pseudopodetia between the phyllocladia, pale to dark brown, verrucose or subbotryose, containing Nos toe or Stigonema. Apothecia rare, lateral, small, 0.5-1.0 mm, blackish; exciple at sides 30-60 µ thick of conglutinated pachydermatous hyphae; central cone hyaline to pale brownish; hypothecium 30-70 µ, pale brownish; hymenium 50-60 µ, upper part reddish brown; paraphyses simple or branched, 1-1.5 µ ripe spores not known.

Reactions: K+ yellow, P+ pale yellowish.

Contents: atranorin and porphyrilic acid (dendroidin).

This species grows on moss and Dryas heaths on hummocks or gravelly soil. It is known from Greenland across westward into Kamtchatka. Morphologically it resembles S. arcticum or S. vesu-vianum but differs in the chemistry.