General:
Minute stratified scale (or crust) lichens, corticate above, ecorticate below, neither sorediate nor isidiate, lobes closely to loosely appressed, mostly elongate, averaging to 0.1–0.3 mm wide, delicate. Upper surface pale whitish or bluish, dull, strongly convex, cortical cells obviously papillate at 400 magnification. Lower surface pale, lacking rhizines. Medulla white. Photobiont green.Ascocarp a perithecium, located over upper surface, protruberant, strawberry-shaped/ampulliform, black; spores muriform, ellipsoid, brown, 1 or 2 per ascus (in BC).

Notes: Agonimia is a widespread genus of north temperate latitudes. It contains two species worldwide, only one of which occurs in B.C. The papillate cortical cells provide a useful diagnostic character for this genus. Chemistry, however, is of no taxonomic value.

Comments:
Mature ascocarps have not yet been found in B.C. Material resembling A. tristicula has been detected over Garry oak on southeast Vancouver Island and can probably be referred to Bacidia rubella (Hoffm.) Massal.

Reactions:
Cortex KC+ yellow.

Contents:
Caperatic and usnic acids.

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:
Polyblastia tristicula (Nyl.) Arnold