General:
Common Name: The Rocktripe Lichens. Traditional, reflecting both the strict occurrence of the species over rock and (apparently) the use of certain species as food in times of famine.
Small to medium stratified foliose lichens, umbilicate, rotund to subrotund, corticate above and below, isidiate or more often not, thalloconidiate or not, lobes developed or not, thallus averaging to 0.5–7 (–15+) cm across, thin or occasionally thick. Upper surface greyish to dark brown. Lower surface tan, brown or black, naked or more or less covered in rhizines, plates and/or papillae. Medulla white. Photobiont green.
Apothecia located over upper surface, disc even or variously fissured or with central protruding button, black; spores simple or multi-celled, ellipsoid, colourless or occasionally brown, (1–) 8 per ascus.
Notes: Umbilicaria is primarily a boreal and arctic genus consisting of approximately 45 species worldwide. Of the 28 species known to occur in North America, 20 are reported for B.C. Earlier authors arranged the species listed below in as many as four genera — Actinogyra, Agyrophora, Omphalodiscus and Umbilicaria — though it is now customary to accommodate them in Umbilicaria. Strongly pustulate species, however, should be checked for in Lasallia. Gyrophoric acid (C+ red) is present in most Umbilicaria species, and norstictic and stictic acids also occur on occasion. Chemistry, however, is of little diagnostic value in this genus and is omitted.

Species description:
Isidia absent; lower surface naked or bearing plates or rhizines, pitted or not AND
Thallus distinctly foliose, attached to substrate by single, more or less central holdfast; upper surface occasionally perforate or segmented, but never chinky-cracked; distribution and ecology various AND
Lower surface (excluding rhizines) pale or brown or, if partly grading to black, then thalloconidia absent (i.e., lacking sharply demarcated black, sooty patches); apothecia usually abundant AND
19a Lower surface (or sometimes lobe margins) bearing numerous rhizines and/or platelike outgrowths AND
Lower surface and/or lobe margins more or less rhizinate; platelike outgrowths absent AND
Upper surface dark, never strongly white-pruinose throughout (pruina, however, sometimes distinct over thallus centre); lower surface pale greyish; apothecial discs much-fissured; distribution various AND
Upper surface either in part net-ridged (check thallus centre) or segmented (check thallus periphery), rest of thallus pustulate or not; peripheral portions of thallus sometimes minutely perforate AND
Upper surface generally net-ridged/reticulate and/or white-pruinose over thallus centre; thallus periphery continuous (i.e., neither segmented nor minutely perforate)

OR

Isidia absent; lower surface naked or bearing plates or rhizines, pitted or not AND
Thallus distinctly foliose, attached to substrate by single, more or less central holdfast; upper surface occasionally perforate or segmented, but never chinky-cracked; distribution and ecology various AND
Lower surface (excluding rhizines) pale or brown or, if partly grading to black, then thalloconidia absent (i.e., lacking sharply demarcated black, sooty patches); apothecia usually abundant AND
Lower surface sometimes minutely textured, lacking rhizines and plates or at most bearing a few scattered cylindrical rhizines; lobe margins never rhizinate AND
Lower surface smooth or at most irregularly and minutely grainy, graininess difficult or impossible to detect with hand lens AND
Upper surface pustulate-ridged or not, but generally also in part distinctly netridged and/or white-pruinose (check central portions); position of holdfast usually readily discernable from above; apothecial discs much-fissured or not AND
Lower surface white-pruinose usually only toward thallus margins; thallus not at all distinctly thick; apothecial disc much-fissured; widespread

Comments:
Specimens from coastal localities often lack the netlike ridges characteristic of this species.

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