''Buellia disciformis'', the boreal button lichen, is a thin, bluish to pale gray rimose to
areolate
Lichens are composite organisms made up of multiple species: a fungal partner, one or more photosynthetic partners, and sometimes a basidiomycete yeast. They are regularly grouped by their external appearance – a characteristic known as their ...
crustose
Crustose is a habit of some types of algae and lichens in which the organism grows tightly appressed to a substrate, forming a biological layer. ''Crustose'' adheres very closely to the substrates at all points. ''Crustose'' is found on rocks a ...
lichen that grows on bark (rarely also on wood) in temperate forests in the northern USA and Europe, and at high altitudes in
Arizona
Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a U.S. state, state in the Southwestern United States. It is the list of U.S. states and territories by area, 6th largest and the list of U.S. states and territories by population, 14 ...
, down to in coastal areas of
California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...
.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, Buellia disciformis, Lichen Flora of the Greater Sonoran Desert Region, Nash, T.H., Ryan, B.D., Gries, C., Bugartz, F., (eds.) 2001 Flat
apothecia
An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are mo ...
with black discs are .2-.7 mm in diameter and
sessile
Sessility, or sessile, may refer to:
* Sessility (motility), organisms which are not able to move about
* Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant
* Sessility (medicine), tumors and polyps that ...
(neither raised or immersed in the
thallus
Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or " twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms ...
), with noticeable
lecideine
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.Lichen spot tests are negative except for K+ yellow.
Secondary metabolites
Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the nor ...
include
atranorin
Atranorin is a chemical substance produced by some species of lichen. It is a secondary metabolite belonging to a group of compounds known as depsides. Atranorin has analgesic, anti-inflammatory, antibacterial, antifungal, cytotoxic, antioxidant ...
, fulgidin, and sometimes traces of fulgoicin and norfulgoicin. '' B. erubescens'' is similar and more often found on wood than the bark loving ''B. disciformis'', and has smaller spores.