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

General:
Common Name: The Rockbright Lichens. Describes the habitat and brightly coloured upper surface of the species.
Small stratified foliose lichens (ours), umbilicate, rotund, corticate above and below, nonsorediate, nonisidiate, lobes poorly developed, entire thallus averaging to 1–2 cm across, thin to thick. Upper surface whitish or pale greenish. Lower surface pale, brownish or blue-black, lacking rhizines. Medulla white. Photobiont green.
Apothecia located over upper surface, usually numerous, disc even, pinkish or brownish to greenish or blackish; spores simple, ellipsoid, colourless, 8 per ascus.
Over acid or base-rich rock.
Notes: Rhizoplaca is primarily a genus of temperate latitudes where it is best represented in semi-arid regions. Of the six species reported for North America, only three occur in B.C.

Species description:
Lower surface continuous or, if cracked, then cracks radial (i.e., never forming distinct netlike pattern); apothecial margins often pruinose, discs pinkish orange, greenish, brownish, or rarely black; medulla PD+ yellow or PD- AND
Apothecial discs pale greenish to olive-brownish or black

Comments:
Some of the B.C. specimens seem to be intermediate between R. melanophthalma and Lecanora muralis (Schreber) Rabenh.; these possibly represent a distinct taxon.

Reactions:
Medulla PD+ yellow or PD-.

Contents:
Usnic, (placodiolic and psoromic acids).