Species description:
Thallus small to medium but not minute; lobes averaging to more than 1.5 mm wide, always dorsiventral; isidia present or absent, distinctly wrinkled upper surface AND
Lobe margins naked; isidia, if present, naked AND
Lobes broad or, if elongate, then never both erect and terminating in distinctly swollen tips; lobe tips averaging to less than 0.2 mm thick when moist, seldom strongly wrinkled when dry; habitat and distribution various AND
Lower surface naked or bearing scattered tufts of hair at points of attachment, never distinctly woolly AND
Isidia and/or lobules present over upper surface AND
Thallus distinctly thin, averaging to less than 0.1 mm thick when moist; distribution various AND
Isidia cylindrical throughout AND
Upper surface bluish grey throughout; over trees (rare over mossy rock); restricted to humid localities; rare

Comments:
Notes: Although Sierk (1964) claims that L. cyanescens “is the most common species of Leptogium in North America,” it is obviously very rare in B.C.

Source:  Lichens of British Columbia

If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Illustration By:  Trevor Goward

Synonyms and Alternate Names:
Leptogium caesium (Ach.) Vainio
Leptogium tremelloides auct.