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 n ...
of
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 ...
lichens with a carbon black ring or outer margin (
exciple
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.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 mo ...
), 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, giv ...
) or in ( endolithic) rock.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, Lichens that have such a black exciple are called
lecideine
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Members of the genus are commonly called disk lichens or tile lichens.
Selected species
According to the ''Dictionary of the Fungi'' (10th edition, 2008), the widespread genus contains an estimated 427 species.
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Lecidea atrobrunnea
''Lecidea atrobrunnea'' is a crustose lichen in the Lecideaceae family, found in mountains of the continental western United States and Alaska. With other lichen communities, it forms dark vertical drip-like stripings along drainage tracks in th ...
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Lecidea hassei
''Lecidea hassei'' (Hasse's lecidea lichen) is an endolithic lichen that appears as tiny black, gray rimmed, plate-like or crinkled discs between crystals of rock in California. The main body grows ''inside'' solid rock (endolithic), and the c ...
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Lecidea keimioeensis
''Lecidea keimioeensis'' (originally published as ''keimioeënsis'') is a species of crustose lichen. It was collected by Finnish botanist Kaarlo Linkola from , Finland, (for which the species is named), and identified as a new species by Edvard ...
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Lecidea laboriosa
''Lecidea laboriosa'' is a species of lichen that grows inside solid rock ( endolithic), with only the small black disc-like fruiting bodies (apothecia) visible above the rock surface.Field Guide to California Lichens, Stephen Sharnoff, Yale Un ...
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Lecidea lithophila
''Lecidea'' is a genus of crustose lichens with a carbon black ring or outer margin (exciple) around the fruiting body disc (apothecium), usually (or always) found growing on (saxicolous) or in ( endolithic) rock.Field Guide to California Lichen ...