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Lichen
composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi in a symbiotic relationship / From Wikipedia, the free encyclopedia
Lichens are a symbiosis of at least two quite different organisms. The partnership always involves a fungus, which lives with one or more partners which can do photosynthesis. The photobiont[1] partner may be a green alga and/or a cyanobacterium.[2]p5,6,13
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The algae or bacteria live inside the fungus, and exchange nutrients with it. The lichen is different in shape and mode of life from any of the partners. It is a distinct form of life. Botanists did not know this until about 1875.[3]
There are more than 2,000 species in Britain and Ireland alone, many of which are found in temperate rainforests.[4]