General:
Common Name: The Rocktripe Lichens. Traditional, reflecting the strict occurrence of the species over rock and the apparent use of a species of the related genus Umbilicaria as food during famine.
Medium to large stratified foliose lichens, corticate above and below, lacking isidia (ours), lobes attached to substrate by a more or less central holdfast, usually rotund, rather thin, thallus averaging to 6–15 (–25) cm across. Upper surface dark brown, blistered/pustulate. Lower surface black (ours), papillate, lacking rhizines.Photobiont green.
Apothecia located over upper surface, disc black; spores multi-celled, ellipsoid, brownish, 1 (rarely 2) per ascus.
Notes: Lasallia is primarily a temperate genus; of the eight species described worldwide, three occur in North America and one in B.C.

Species description:
Upper surface bearing well-spaced, discrete blisters/pustules, ridges absent; apothecial disc plane AND
Lower surface black, distinctly textured

Comments:
Lasallia papulosa is also reported for B.C., though the record is questionable

Reactions:
Medulla C+ reddish, KC+ reddish.

Contents:
Gyrophoric and ovoic acids, with traces of lecanoric and hiascic acids (umbilicaric acid).

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:
Umbilicaria pensylvanica Hoffm.