Gourt > Science > Biology > Mycology > Lichens
Lichens are symbiotic organisms made up by the association of microscopic green algae or cyanobacteria and filamentous fungi. There is evidence that lichens might involve a controlled form of parasitism of the algal cells. In laboratory settings, algae grow faster when they are alone rather than when they are part of a lichen. But there is also a mutualism side to the relationship, the fungus part of the lichen provides the alga with water and minerals that the fungus absorbs from whatever the lichen is growing on. As for the alga, it uses the minerals and water to make food for the fungus and itself. Lichens take the external shape of the fungal partner and hence are named based on the fungus. The fungus most commonly forms the majority of a lichen's bulk, though in filamentous and gelatinous lichens this may not always be the case. The lichen fungus is typically a member of the Ascomycota—rarely a member of the Basidiomycota. Some lichen taxonomists place lichens in their own division, the Mycophycophyta, but this practice ignores the fact that the components belong to separate lineages.
The algal or cyanobacterial cells are photosynthetic, and as in higher plants they reduce atmospheric carbon dioxide into organic carbon sugars to feed both symbionts. Both partners gain water and mineral nutrients mainly from the atmosphere through rain and dust. The fungal partner protects the alga by retaining water, serving as a larger capture area for mineral nutrients and, in some cases, provides minerals obtained from the substratum. If a cyanobacterium is present, as a primary partner or another symbiont in addition to green alga as in certain tripartite lichens, they can fix atmospheric nitrogen, complementing the activities of the green alga.
Morphology and structure
Lichens live on various surfaces, such as soil, wood, and rock. They are often the first to settle in places lacking soil, constituting the sole vegetation in some extreme environments such as those found at high mountain elevations and at high latitudes. Some survive in the tough conditions of deserts, and others on frozen soil of the arctic regions. Recent ESA research shows that lichens can even endure extended exposure to space. Some lichens have the aspect of leaves (foliose lichens); others cover the substratum like a crust (crustose lichens); others adopt shrubby forms (fruticose lichens); and there are gelatinous lichens (see lichen forms to the right ->). More on [ Lichen ]
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EurekAlert! - Biology
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Air Pollution, Lichens and Mosses - Brief article.
Arizona State University Lichen Herbarium - Information about the collection, the Sonoran Desert Lichen Flora Project, research, and online course material.
British Lichen Society - Advance interest in all branches of lichenology. Includes comprehensive information on British lichens.
Meta Description: [ The British Lichen Society. The Society was formed in 1958 to stimulate and advance interest in all branches of lichenology. ]
Churchyard Lichens - General information.
Dutch Lichens - Photos and information about lichen biology. In Dutch and English.
Endangered Lichens - List of species protected by law in different countries.
European Species of the Lecanoraceae Family - Information on monograph.
Information about Lichens - Description, structure, and environmental importance.
Introduction to Lichens - Information about lichens - their fossil record, life history, ecology, morphology and systematics.
Invasion of Pollution-tolerant Lichens - Research on the distribution of four pollution-tolerant non-native lichens in the Pacific Northwest.
Lichen Biology - Introduction to lichens, which are stable, self-supporting associations between fungi (most commonly Ascomycota) and photobionts (algae or cyanobacteria). Intended for university students.
Meta Description: [ Introduction to Fungal Biology for university students studying biological science. ]
Lichen Research Program, University of Maine at Fort Kent - Information about Steve Selva's research program in lichenology. Includes a photo gallery of stubble lichens under the microscope.
LichenLand - General information for young students including synoptic key and photos.
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Lichenology in the Netherlands - Red list including lichenicolous fungi, and additional information about projects and publications.
Meta Description: [ Website about lichenology in the Netherlands. ]
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Lichens - Silent Witnesses of Air Quality - Information on monitoring air quality, bibliography, and photos.
Lichens of North America - Information about lichen biology, lichens and wildlife, lichens and people, and the book of the same title, which was published in 2001.
Lichens.de - Photos of lichens taken during British Lichen Society field trips in Britain. Contains general information and related links.
New Zealand Forest Lichens - Photographs, general information, identification and related links.
Meta Description: [ This site contains photographs of New Zealand lichens and general information on them. ]
North American Lichen Checklist - List of cumulative updates to the most recently published North American checklist by Esslinger and Egan (1995).
Rhode Island's Foliose and Fruticose Lichens - Habitat notes, distribution maps, and color photographs of over 90 species of macrolichens by Don Flenniken.
| Up and coming artist Dave Lichens performs "Let Go" which is featured in the Dreamworks film She's The Man. ... Dave ... | |
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