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

General:
Common Name: The Loop Lichens. Describes the conspicuously rounded axils of the lobes.
Small to medium stratified foliose lichens, corticate above and below, sorediate (in BC), lobes loosely appressed to loosely attached, short to elongate, averaging to (0.7–) 1–5 mm wide, thin. Upper surface greenish or greyish, somewhat shiny. Lower surface black, shiny, bearing forked rhizines. Medulla white. Photobiont green.
Apothecia unknown in B.C. material.
Over bark and rock.
Notes: Hypotrachyna is primarily a tropical genus consisting of about 80 species worldwide. Twenty-three of these occur in North America, though only two species are known in B.C.

Species description:
Upper surface distinctly yellowish green; lobes mostly elongate-linear; cilia absent over margins AND
Lobes loosely appressed to semi-erect; rhizines strongly fork-branching; coastal; medulla K+ yellow becoming reddish

Reactions:
Medulla K+ yellow becoming reddish, PD+ orange.

Contents:
Salazinic and usnic acids (and norstictic and stictic acids).