Varicellaria lactea

Varicellaria lactea is a crustose lichen in the family Varicellariaceae. It forms a relatively thick, white to grey‑white, matt crust that breaks into small, tile‑like patches and carries scattered white, powdery soralia (patches that shed tiny propagules); sexual fruiting bodies are rare, and when present they produce a single very large spore, with the lichen containing lecanoric and variolaric acids. Ecologically it is chiefly rock‑dwelling on lime-free siliceous and volcanic rocks in humid, shaded situations, and is widespread in Europe with confirmed records from the Azores, South Korea, and Alaska. First described by Carl Linnaeus in 1767 as Lichen lacteus, the name was fixed by a neotype designated in 1994 and the species was transferred to Varicellaria in 2012 following a multi‑gene revision that separated the genus from Pertusaria in the strict sense. It is usually distinguished from the related V. hemisphaerica by its rock substrate and the presence of variolaric acid, wherea......read more on Wikipedia.