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Evernia perfragilis Llano
Family: Parmeliaceae
Evernia perfragilis image
Lucy Taylor  
Thompson, J., 1984. American Arctic Lichens: The Macrolichens.
Thallus fruticose, erect, in tufts, 2-5 cm tall, brittle and fragile, breaking into pieces when dry; the main branches to 1.5 mm thick, angularly compressed, dichotomously branching, smooth or roughened to rugose, tips attenuate, lacking soredia or isidia, pale yellowish; cortex chondroid, to 55 μ thick, the cells more or less longitudinally arranged, paraplectechymatous; medulla white, dense. Apothecia and pycnidia not known. 

Reactions: K— , C— , KC— , P— .

Contents: usnic and divaricatic acids.

This species grows on calcareous soils and gravels. It is amphi-Beringian, not being found in Europe but ranging very widely in the arctic from Novaya Zemlya across the high arctic in Siberia and across northern North America to the east side of Baffin Island.