Common Button Lichen

<em>Buellia erubescens</em>, commonly known as the common button lichen, is a lichen species with documented occurrences across Asia, Europe, and North America, including countries such as Norway, Portugal, Sweden, Taiwan, and the United States. It typically colonizes diverse terrestrial surfaces, often found on bark, rock, or other substrates in temperate and boreal environments. Common button lichen belongs to the genus <em>Buellia</em> within the family Caliciaceae. As a crustose lichen, it typically forms tightly adhered, crust-like thalli on the surfaces it colonizes, making it characteristic of stable, undisturbed substrates. Biological traits such as average lifespan, thallus size, and biomass of this species remain poorly documented in the scientific literature. The species has not yet been formally evaluated by the IUCN, and its global conservation status therefore remains undetermined. Its occurrence across multiple continents suggests a wide ecological tolerance, though detailed population data and trend assessments are currently lacking for this taxon.