Viruses, Bacteria, Protists, and Fungi

What are lichens?

Lichens are organisms that grow on rocks, tree branches, and bare ground. They are composed of two different entities living together in a symbiotic relationship: 1) a population of either algal or cyanobacterial cells that are single or filamentous; and 2) fungi. Lichens do not have roots, stems, flowers, or leaves. The fungal component of the lichen is called the mycobiont (Greek mykes, “fungus” and bios, “life”) and the photosynthetic component is called the photobiont (Greek photo, light and bios, life). The scientific name given to the lichen is the name of the fungus and is most often an ascomycete. As the fungus has no chlorophyll, it cannot manufacture its own food, but can absorb food from algae. Lichens and algae enjoy a symbiotic relationship. Lichens can often be found growing around and on top of algae, providing the algae protection from the sun thus decreasing the loss of moisture. Fungi and algae were the first organisms recognized as having a symbiotic relationship. A unique feature of this relationship is that it is so perfectly developed and balanced that the two organisms behave as a single organism.


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