Lichens ( /ˈlaɪkən/, sometimes /ˈlɪtʃən/) are composite organisms consisting of a fungus (the mycobiont) and a photosynthetic partner (the photobiont or phycobiont) growing together in a symbiotic relationship. The photobiont is usually either a green alga (commonly Trebouxia) or cyanobacterium (commonly Nostoc). The morphology, physiology and biochemistry of lichens are very different from those of the isolated fungus and alga in culture. Lichens occur in some of the most extreme environments on Earth—arctic tundra, hot deserts, rocky coasts, and toxic slag heaps. However, they are also abundant as epiphytes on leaves and branches in rain forests and temperate woodland, on bare rock, including walls and gravestones, and on exposed soil surfaces (e.g., Collema) in otherwise mesic habitats. Lichens are widespread and may be long-lived; however, many are also vulnerable to environmental disturbance, and may be useful to scientists in assessing the effects of air pollution, ozone depletion, and metal contamination. Lichens have also been used in making dyes and perfumes, as well as in traditional medicines.

Read more about Lichen:  Overview, History, Symbionts, Morphology and Structure, Growth Form, Reproduction and Dispersal, Ecology, Evolution and Paleontology, Taxonomy and Classification, Gallery

Other articles related to "lichen":

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... Smith, reindeer carcasses were stuffed with lichen and powdered glass, and suggests that the sharp edges of the glass would make the animals' internal organs more susceptible ... However, it is known that the lichen itself is also effective—powdered lichen added to fat and inserted into reindeer carcasses will also be fatal to wolves that consume it ...
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Lichen Scrofulosorum
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Famous quotes containing the word lichen:

    The lichen on the rocks is a rude and simple shield which beginning and imperfect Nature suspended there. Still hangs her wrinkled trophy.
    Henry David Thoreau (1817–1862)

    What do the botanists know? Our lives should go between the lichen and the bark. The eye may see for the hand, but not for the mind. We are still being born, and have as yet but a dim vision of sea and land, sun, moon, and stars, and shall not see clearly till after nine days at least.
    Henry David Thoreau (1817–1862)