[h=1]Mycelium[/h] From Wikipedia, the free encyclopedia
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Fungal mycelia
Microscopic view of a mycelium. This image covers a one-millimeter square.
Another microscopic view of a mycelium. Numbered ticks are 230 µm apart.
Oyster mushroom (Pleurotus ostreatus) growing on coffee grounds
Mycelium (plural
mycelia) is the
vegetative part of a
fungus, consisting of a mass of branching, thread-like
hyphae. The mass of hyphae is sometimes called
shiro, especially within the
fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other substrates. A typical single
spore germinates into a
homokaryotic mycelium, which cannot reproduce sexually; when two compatible homokaryotic mycelia join and form a dikaryotic mycelium, that mycelium may form
fruiting bodies such as
mushrooms. A mycelium may be minute, forming a colony that is too small to see, or it may be extensive:
Is this the largest organism in the world? This 2,400-acre (9.7 km[SUP]2[/SUP]) site in eastern Oregon had a contiguous growth of mycelium before logging roads cut through it.Estimated at 1,665 football fields in size and 2,200 years old, this one fungus has killed the forest above it several times over, and in so doing has built deeper soil layers that allow the growth of ever-larger stands of trees. Mushroom-forming forest fungi are unique in that their mycelial mats can achieve such massive proportions.
—
Paul Stamets,
Mycelium Running
It is through the mycelium that a fungus absorbs
nutrients from its environment. It does this in a two-stage process. First, the hyphae secrete
enzymes onto or into the food source, which break down
biological polymers into smaller units such as
monomers. These monomers are then absorbed into the mycelium by
facilitated diffusion and
active transport.
Mycelia are vital in terrestrial and aquatic
ecosystems for their role in the
decomposition of plant material. They contribute to the organic fraction of soil, and their growth releases
carbon dioxide back into the atmosphere. The mycelium of
mycorrhizal fungi increases the efficiency of water and nutrient absorption of most plants and confers resistance to some plant pathogens. Mycelia are an important food source for many soil invertebrates.
Sclerotia are compact or hard masses of mycelia.