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

General:
Common Name: The Rag Lichens. Describes the broad, pale, somewhat uneven lobes of the species.
Medium to large stratified foliose lichens, corticate above and below, sorediate, lobes loosely appressed to loosely attached, short, thin, averaging to 1–1.5 cm wide. Upper surface whitish or pale tan, pseudocyphellate. Lower surface mostly black, shiny, bearing sparse, short simple rhizines. Medulla white. Photobiont green.
Apothecia unknown in B.C. material.
Notes: Cetrelia is essentially a temperate genus consisting of about 14 species worldwide. Five of these are reported for North America, though only one is known to occur in B.C. For points of distinction with similar species in other genera, see the descriptions under Platismatia.

Comments:
Cetrelia cetrarioides is very similar to C. olivetorum (Nyl.) Culb. & C. Culb. and is often treated as a chemotype of that species.