Concentric Ring lichen {Arctoparmelia centrifuga}

 Arctoparmelia centrifuga (aka “Xanthoparmelia centrifuga” or “Concentric Ring Lichen”)

Description: Lower surface pale.  Lobes flat to slightly convex, 1-2 mm wide, without soredia or isidia; lower surface white or almost white, with scattered dark rhizines.

Apothecia: Fairly common.

Range: Mainly arctic & boreal south to central British Columbia.

Lookalikes: The white lower surface distinguishes this lichen from the much rarer Arctoparmelia separata & Arctoparmelia incurva; both have a mouse-gray lower surface, & Arctoparmelia incurva produces large, irregular sorelia on the upper surface.  Rarely, Arctoparmelia centrifuga lacks usnic acid & a gray instead of yellow-green, with the cortex reacting K+ yellow, KC-.

Uses: In the Arctic, Arctoparmelia centrifuga has been used as a source of red-brown dyes for wool.

Bibliography:  Macrolichens of the Pacific Northwest, by Bruce McCune & Linda Geiser,Lichens of North America, by Brodo, Sharnoff, & Sharnoff

Database Entry: Distance Everheart 8-1-13


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