What is a lichen composed of?

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ncchemist | eNotes Employee

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Lichens are composed of two different organisms living together as a new entity.  One of the components is a fungus and the other is a photosynthetic autotroph, usually an algae.  It forms a biological structure that is different than a simple mixing of its host constituents.  The fungal cells surround the algae cells to act as a form of protective barrier.  In terms of appearance, lichens often appear as thin flaky or crusty patches that cover and grow on trees, rocks, or old buildings.

In terms of whether the relationship between the fungus and the algae is symbiotic or parasitic is something of a debate.  A symbiotic relationship means that both organisms benefit from the arrangement.  The fungus certainly benefits, receiving food and nutrients from the food-producing algae.  But it has been shown that while the algae can survive independent of the fungus, the opposite is not true.  So the fungus could be seen as more of a parasite than a symbiont.

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lan950s's profile pic

lan950s | High School Teacher | (Level 2) Adjunct Educator

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A lichen is NOT a plant like mentioned above.

atyourservice's profile pic

atyourservice | Student, Grade 11 | (Level 3) Valedictorian

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lichen is made out of fungus and a type of algae (for photosynthesis)

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acompanioninthetardis | Student, Undergraduate | (Level 1) Valedictorian

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lichens are basically a combination of fungus and a type of algae (usually green algae and cyanobacteria). They are typically in a mutual symbiosis with other organisms. They are also the first colonists in barren environments. They usually come in 3 main body forms:

Fruticose: typically flat finger-like extensions

Foiliose: leaf- like extensions

Crustose: matted thick fungus on rocks

lichens are excellent indicators of air quality and play a role in turning rocks into soil.  

 
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sid-sarfraz's profile pic

sid-sarfraz | Student, Graduate | (Level 2) Salutatorian

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Lichen is not a single organism. It basically is a combination of two or more organisms by symbiotic relationship. One is algae that contains chlorophyll for the photosynthesis process where as other is fungus that absorbs the nutrition from algae.

So basically a lichen is composed of following:-

  1. Fungal Filaments
  2. Algae cells
  3. Sometimes cynobacteria

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