Order: Pertusariales       Family: Pertusariaceae Species: Lepra amara (Pertusaria amara) Growth type crustose. Photos: On Oak and rock. Co. Cork and Co. Kerry, SW Ireland Very variable. Thallus thick or thin, grey, +/- zoned at margins with punctiform soralia +/- regularly scattered over surface. Whitish farinose soredia with persistent very bitter taste. (Test with just a few grains on a moist finger.) Apothecia very rare. Usually found on deciduous trees, occasional on conifers and rocks. Widespread throughout Ireland but most frequent in eastern half. Soralia and medulla K-, C-, KC+ violet (fleeting), P+/- red, UV- Positive taste test for oxalic acid is unmistakeable. Similar: Pertusaria albescens, taste test negative.

Lepra amara (Pertusaria amara) January and November 2010