genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.exciple) around the fruiting body disc (
apothecium
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 mos ...
), usually (or always) found growing on (
saxicolous
A saxicolous lichen is a lichen that grows on rock. The prefix "sax" from the Latin means "rock" or "stone".
Characteristics
Saxicolous lichens exhibit very slow growth rates. They may develop on rock substrates for long periods of time, give ...
) or in (
endolithic
An endolith or endolithic is an organism (archaeon, bacterium, fungus, lichen, algae or amoeba) that is able to acquire the necessary resources for growth in the inner part of a rock, mineral, coral, animal shells, or in the Porosity, pores bet ...
) rock.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, Lichens that have such a black exciple are called lecideine, meaning "like ''Lecidea'', even if they are not in this genus. Members of the genus are commonly called disk lichens or tile lichens.