Lepra amara var. flotowiana  (Flörke) Nimis

 

=Pertusaria amara var. flotowiana (Flörke) Erichsen

   Thallus crustose, whitish, greyish, white-ochraceous, delimited, margin not zonate, more or less wrinkled, verrucose and cracked, covered with verrucose soralia, 1-3 mm diam., whitish, giving a cauliflower aspect, and with a surface covered with minute erect finger-like soredia. Apothecia absent. C-, K-, KC+ purple (clear on fresh samples), Pd+/- golden-yellow to orange (this chemotype is more frequent than the one observed on tree barks). On slightly acid rocks or slightly alkaline walls in the aerohaline zone, extends also to the 'oceanic' zone on old walls near the seashore and potentially to rocky ridges inland. N.B. The strong bitter taste of this species makes it easy to recognize among other close species. It is the most common variety (or morph) of  Lepra amara found on rocks. N.B. This taxon is not taken into consideration by several authors.