E-Flora BC: Electronic Atlas of the Flora of British Columbia

General:
Common Name: The Scatter-rug Lichens. Alludes to the broad lobes and ciliate margins characteristic of the species.
Medium stratified foliose lichens, corticate above and below, sorediate or isidiate or not, sparsely ciliate (in BC), lobes loosely attached to partly semi-erect, short to somewhat elongate, averaging to 5–10 mm wide, thin. Upper surface whitish to pale greyish, smooth. Lower surface blackening, shiny, bearing numerous simple rhizines, but marginal area lacking rhizines. Medulla white. Photobiont green.
Apothecia unknown in B.C. material.
Over trees, rarely over rock.
Notes: Parmotrema is primarily a temperate and tropical genus consisting of approximately 100 species (excluding Rimelia Hale and Fletcher). Thirty-six of these occur in North America and only three in B.C. Parmotrema was formerly treated as a subgenus within Parmelia.

Species description:
Thallus sorediate; cilia restricted to lobe margins AND
Upper surface lacking pseudocyphellae; lobe margins ciliate or not AND
Soralia narrow to more often head-shaped, sharply delimited, densely packed with soredia; cilia usually more than 2 mm long; rhizines often abruptly longer toward thallus centre; medulla C- AND
Cilia more or less evenly distributed, usually averaging to more than 3 mm long; soredia often brownish when mature; medulla K-, KC+ reddish

Reactions:
Cortex K+ yellow; medulla KC+ reddish.

Contents:
Alectoronic and atranorin acid (and rhodophyscin).