Cetraria islandica ssp. crispiformis
Cetraria islandica ssp. islandica

General:
Small to large stratified foliose lichens, corticate above and below, sorediate or not, lobes rather closely appressed to semi-erect or erect, short to more often elongate, averaging to 0.5–10 (–12) mm wide, thin to somewhat thick, occasionally bearing protruberant marginal pycnidia or cilia. Upper surface brownish, blackish, or brightly coloured; lower surface coloured alike with upper surface, often lacking rhizines. Medulla white (rarely yellow). Photobiont green. Apothecia located along lobe margins, disc brown or black; spores simple, spherical or ellipsoid, colourless, 8 per ascus.

Notes: Thirty-eight species of Cetraria are reported for North America. Nineteen of these occur in B.C. As presently delimited, Cetraria is a heterogeneous genus. Although several species groups are segregated from it as distinct genera (e.g. Asahinea, Cetrelia, Esslingeriana, Masonhalea, Platismatia and Vulpicida), a number of other species and species groups also deserve generic rank. Recently Hale (1987) transfered some of these to Tuckermannopsis. This disposition, however, seems more nomenclatural than taxonomic and is not followed here. Also not accepted here (pending further study) is the separate genus Allocetraria (Randlane and Saag 1992).

Comments:
Two subspecies of C. islandica occur in B.C., distinguished by the characters outlined in the descriptions. A third subspecies, ssp. orientalis (Asah.) Kärnef., has also been reported, but no specimens have been examined by us.

Reactions:
Medulla K- or K+ yellowish, PD+ yellowish or reddish or PD-.

Contents:
Lichesterinic and protolichesterinic acids (and fumarprotocetraric acid).

Source:  Lichens of British Columbia