Lepraria bergensis

Lepraria bergensis is an uncommon crustose lichen in the family Stereocaulaceae. It occurs in Northern and Central Europe, where it grows on siliceous (silicon-rich) rock walls, particularly under small overhangs, and on mosses on vertical to slightly sloping rock surfaces. The lichen thallus forms as a pale bluish-grey crust-like growth on rocks and mosses. The lichen begins as small, rounded patches a few millimetres wide, which may eventually coalesce into larger areas exceeding 1 centimetre in diameter. The thallus has a powdery texture, consisting of minute granules known as soredia and consoredia, which facilitate the lichen's asexual reproduction. The chemical composition of Lepraria bergensis is distinguished by the presence of several secondary metabolites: atranorin, rangiformic acid or jackinic acid, trace amounts of their respective derivatives, and a variety of anthraquinones. These chemical components cause the lichen to fluoresce a dull yellow under long-wave ultraviole......read more on Wikipedia.