lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.fungi in the family Caliciaceae. The fungi are usually part of a crustose lichen. In this case, the lichen species is given the same name as the fungus. But members may also grow as parasites on lichens ( lichenicolous). The
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
in the lichen (the photobiont partner) is always a member of the genus ''
Trebouxia
''Trebouxia'' is a unicellular green alga.Silverside, A. J. (2009). Retrieved from http://www.bioref.lastdragon.org/Chlorophyta/''Trebouxia''.html It is a photosynthetic organism that can exist in almost all habitats found in polar, tropical, and ...
''.
Lichens in the genus are commonly called disc lichens, or button lichens.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, The genus has a widespread distribution and contains about 450 species.
Genetic studies indicate that the genus '' Amandinea'' and ''Buellia'' may be the same,Scheidegger, C. 2009. Amandinea Choisy ex Scheid. & H. Mayrhofer (1993). In: C. W. Smith, A. Aptroot, B. J. Coppins, A. Fletcher, O. L. Gilbert, P. W. James and P. A. Wosley (eds.) The Lichens of Great Britain and Ireland. The British Lichen Society, Natural History Museum Publications, United Kingdom, pp. 142–144 although this is not widely accepted.Amandinea punctata in the Joshua Tree National Park (California, U.S.A.) Map collection: Kerry Knudsen, Kocourková Jana; Czech University of Life Sciences Prague, Faculty of Environmental Sciences, Department of Ecology, Czech Republic; 2012
Buellia disciformis
''Buellia disciformis'', the boreal button lichen, is a thin, bluish to pale gray rimose to areolate crustose lichen that grows on bark (rarely also on wood) in temperate forests in the northern USA and Europe, and at high altitudes in Arizona, ...
Buellia disciformis
''Buellia disciformis'', the boreal button lichen, is a thin, bluish to pale gray rimose to areolate crustose lichen that grows on bark (rarely also on wood) in temperate forests in the northern USA and Europe, and at high altitudes in Arizona, ...
''
Image:Buellia_stillingiana.jpg, ''
Buellia stillingiana
''Buellia'' is a genus of mostly lichen-forming fungi in the family Caliciaceae. The fungi are usually part of a crustose lichen. In this case, the lichen species is given the same name as the fungus. But members may also grow as parasites on li ...
''
Image:Buellia disciformis-2.jpg, Photograph of a cross section of an apothecium from ''B. disciformis'' taken through a compound microscope (x400), showing numerous brown, 1-septate spores per ascus.
Image:Buellia disciformis-4.jpg, Photograph of brown, 1-septate (2-celled) spores from ''B. disciformis'' taken through a compound microscope, x1000. (spores measure 27 x 11 micrometres)