- 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.
- Pathology. any of various eruptive skin diseases.
- to cover with or as if with lichens.
Origin of lichen
Examples from the Web for lichen
There was no soil, no moss, no lichen, no trace of vegetation.
And no sign of life, save for an occasional patch of lichen on a rock.Longevity
These rocks are well tinted 236 with lichen, but they present a barren appearance.Wild Life on the Rockies
Enos A. Mills
It clings to the mind, when it has once seized on it, like a lichen on the rock.Frankenstein
Mary W. Shelley
Dampier, the traveller, used this lichen for the same purpose.A Book about Doctors
John Cordy Jeaffreson
- 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)
- pathol any of various eruptive disorders of the skin
Word Origin and History for lichen
c.1600, from Latin lichen, from Greek leichen, originally "what eats around itself," probably from leichein "to lick" (see lick). Originally used of liverwort; the modern sense first recorded 1715. Related: Lichenaceous.
- Any of various skin diseases characterized by patchy eruptions of small, firm papules.
- 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.