lichen

American  

[lahy-kuhn] / ˈlaɪ kən /

noun

1. any complex organism of the group Lichenes, composed of a fungus in symbiotic union with an alga and having a greenish, gray, yellow, brown, or blackish thallus that grows in leaflike, crustlike, or branching forms on rocks, trees, etc.

2. Pathology. any of various eruptive skin diseases.

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verb (used with object)

1. to cover with or as if with lichens.

lichen British  

/ ˈlɪtʃən, ˈlaɪkən /

noun

1. an organism that is formed by the symbiotic association of a fungus and an alga or cyanobacterium and occurs as crusty patches or bushy growths on tree trunks, bare ground, etc. Lichens are now classified as a phylum of fungi ( Mycophycophyta )

2. pathol any of various eruptive disorders of the skin

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lichen Scientific  

/ lī′kən /

1. The mutualistic symbiotic association of a fungus with an alga or a cyanobacterium, or both. The fungal component of a lichen absorbs water and nutrients from the surroundings and provides a suitable environment for the alga or cyanobacterium. These live protected among the dense fungal hyphae and produce carbohydrates for the fungus by photosynthesis. Owing to this partnership, lichens can thrive in harsh environments such as mountaintops and polar regions. The more familiar lichens grow slowly as crusty patches, but lichens are found in a variety of forms, such as the tall, plantlike reindeer moss. The association between the different organisms in a lichen is so close that lichens are routinely referred to as a single organism, and scientists classify lichens using the name of the fungal component.

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Other Word Forms

• lichen-like adjective
• lichened adjective
• lichenization noun
• lichenlike adjective
• lichenoid adjective
• lichenous adjective
• unlichened adjective

Etymology

Origin of lichen

1595–1605; < Latin līchēn < Greek leichḗn

Example Sentences

They support more life than any other native tree species in the UK, hosting more than 2,300 species, including birds, mammals, insects, fungi, and lichens.

From BBC

An "extinction crisis" is happening in Britain's temperate rainforests where some of the world's rarest mosses, lichens and liverworts are vanishing, ecologists have warned.

From BBC

On the salvaged tiles alone, you can find salt efflorescence, water stains, fretting, lichen, smears of soot, scratches and gashes.

From Los Angeles Times

Also known as Celtic rainforest, the habitat harbours scarce plants, lichens and fungi, and is considered more threatened than tropical rainforest.

From BBC

It is one of the region's largest oaks and a vital ecosystem for rare lichens like the black-eyed Susan.

From BBC