What function does mycelium have: from nature to materials

Mycelium is the vegetative body of fungi: a network of extremely thin filaments, called hyphae, that grows in soil and wood. Its primary function in nature is to decompose dead plant matter, such as leaves, branches, and trunks, and return the nutrients it contains to the soil.

The mushroom we pick in the woods is only a small part of it, the part used to produce spores. The rest of the organism works underground, almost always invisible.

Let's look at what mycelium is, where it lives, what it feeds on, and how long it can last. Then we will follow the transition from nature to production: how the same ability to bind plant matter allows for growing materials for packaging, displays, and furniture.

What is mycelium and what does the term mean

The word mycelium comes from the scientific Latin mycelium, constructed from the Greek mýkēs, which means fungus. The Treccani Vocabulary defines it as the body of the fungus, i.e., its vegetative apparatus, formed by a collection of filaments lacking chloroplasts, the organelles with which plants perform photosynthesis.

Without chloroplasts, the fungus cannot produce sugars from light as plants do, so it must obtain its nourishment from the organic matter surrounding it.

It is often said that mycelium is the root of the fungus. It is a convenient but inaccurate comparison: the root is an organ of a plant, whereas the mycelium is the organism itself. The mushroom that sprouts from the ground is the part used for reproduction.

What is a hypha and what is it for

Hyphae are the filaments that make up mycelium. They originate from the germination of spores, branch out, and, by intertwining, form a dense network that explores the soil or wood in search of food.

Through the hyphae, the fungus absorbs nutrients. They are the point of contact between the organism and the material it feeds on.

What is mycelium made of

The walls of the hyphae are composed primarily of chitin, a polysaccharide, along with glucans and proteins. According to the fact sheets from the European research program CORDIS, it is precisely these components that form a fibrous and interconnected network that gives mycelium strength and versatility. Thanks to this characteristic, mycelium, in addition to feeding, also manages to hold together the matter on which it grows.

What is the difference between a thallus and mycelium

Thallus is a more general term. The Treccani Encyclopedia defines it as the body of a plant organism that is not differentiated into true tissues, and in which, therefore, roots, stems, and leaves are not recognized. It is typical of algae, lichens, and multicellular fungi.

Mycelium is the thallus of fungi. Every mycelium is therefore a thallus, but not every thallus is a mycelium: that of an alga, for example, has an entirely different structure.

The distinction also helps clarify the root misconception. Precisely because it is a thallus, the mycelium has no roots: it is a single body made of filaments.

What function does mycelium have in nature

Mycelium is one of the great recyclers of ecosystems. The hyphae penetrate dead plant matter, such as wood, leaves, and straw, and release enzymes outside that break it down into simpler molecules. The fungus absorbs these molecules to feed itself, while nitrogen, phosphorus, and other minerals become available again in the soil for other organisms, as explained by the fungal biology research group at the Technical University of Munich.

Their role weighs most heavily on a material that is difficult to degrade: lignocellulose. It is the complex of cellulose, hemicellulose, and lignin that provides structure to wood and stems. A study from Utrecht University published in Environmental Microbiology identifies fungi that decompose wood and litter as the primary decomposers of lignocellulose, and thus as key players in the carbon cycle.

Not all fungi, however, live on dead matter. Some species live in symbiosis with plants and, according to the same Munich group, can help them absorb water and nutrients from the soil. Others are parasitic and attack living organisms.

What does mycelium eat

Mycelium feeds on organic matter rich in carbon, which it cannot produce on its own. Fungi that decompose, known as saprotrophs, prefer plant residues: dead wood, fallen leaves, straw, and other agricultural waste.

The species makes the difference. Each fungus has its favorite substrates and its own way of attacking lignin and cellulose, which is why those who cultivate mycelium carefully choose the combination of species and starting material.

Where is mycelium found

Mycelium grows wherever there is organic matter to decompose and enough humidity. It can be found in the soil of forests and meadows, in leaf litter, inside fallen trunks, and under the bark of trees.

Most of it remains hidden. When a layer of damp leaves is moved or a rotten branch is broken, it sometimes appears as a white, cottony web: that is mycelium at work.

The same materials the fungus finds in nature are also found in the waste from human activities. Straw, sawdust, and agricultural residues are, for a fungus that decomposes wood, food just like a fallen branch. From this comes the idea of using it to transform waste into new materials.

From mycelium to mushroom: what happens when it matures

The cycle starts from a spore. When it finds a suitable environment, the spore germinates and gives rise to the first hyphae, which, by growing and intertwining, form the mycelium.

If the temperature and humidity conditions are just right, the mature mycelium forms the fruiting body, that is, the mushroom we know. Botanists also call it a carpophore or sporophore: the FAO AGROVOC thesaurus describes it as the structure that carries and produces spores.

The spores released by the mushroom are dispersed into the environment and, where they find nourishment, give life to a new mycelium. The mushroom, therefore, is the fruit, and the mycelium is the organism that produces it.

How long does mycelium live

As long as it finds food and suitable conditions, a mycelium can continue to grow for a very long time. The most cited case is a specimen of Armillaria ostoyae in the Malheur National Forest, in Oregon. According to the Oregon Encyclopedia, it covers about 965 hectares and, by the highest estimates, could be 8,650 years old.

These are numbers to be taken with caution. Age is derived from the speed at which the fungus expands, which in this case ranges from about 20 centimeters to a meter per year, so estimates change significantly depending on the calculations. The point remains valid: in nature, a mycelium has no fixed lifespan.

For mycelium-based materials, the story is different. Once the mycelium has colonized the entire substrate, the material is heated to remove moisture and stop growth. The review published in 2023 in the Alexandria Engineering Journal describes the result as an inert and lightweight material: the fungus is no longer active.

How is mycelium used

The most well-known use is the cultivation of mushrooms to eat. The champignon, for example, is cultivated by growing its mycelium on compost until it produces the fruiting bodies to be harvested.

In recent years, a second use has been added. Instead of the mushroom, the mycelium itself is exploited for its ability to colonize plant waste and hold it together. The result is materials that grow instead of being manufactured.

Biofabrication: how mycelium becomes a material

Biofabrication uses living organisms to produce materials. With mycelium, the procedure described in literature follows four steps: a substrate of plant waste is prepared, it is inoculated with the fungus, it is left to grow inside a mold, and finally it is dried with heat.

During growth, the hyphae wrap around the waste particles and bind them together. A European research project, MyBond, describes mycelium as a natural glue that joins the substrate. It is the mycelium itself that acts as the binder, and the material takes the shape of the mold in which it grows.

We explore the stages of the process further in the article dedicated to biofabrication with mycelium.

Mycelium and upcycling: from waste to a new product

Upcycling transforms a waste material into a product of higher value. Mycelium does this by nature: it feeds on what remains from crops and sawmills and transforms it into a new material.

L-ife works exactly this way, using straw and wood waste to grow packaging, design objects, and displays. We talk about this in the article on upcycling from nature.

Is mycelium a construction material?

Not for load-bearing structures. Today, mycelium composites are studied and used for elements that do not support significant loads, such as panels, insulation, cladding, and furniture. This is confirmed by the review by Alaneme and colleagues published in 2023 in the Alexandria Engineering Journal, which gathers the results of dozens of studies.

The data that follow come from sector research and concern various experimental materials. The properties change significantly depending on the fungal species, the substrate, the growth conditions, and the processing.

• Thermal insulation. In several studies, thermal conductivity—that is, the ease with which heat crosses the material—is placed between 0.05 and 0.07 W/mK. The lower the number, the better the material insulates. These values are close to those of glass wool, indicated by the same review at 0.04 W/mK.

• Acoustic absorption. Some composites grown on rice straw, hemp, and linen have shown in tests noise absorption better than commercial ceiling panels and polyurethane foams.

• Lightweight. Compressive strength is lower than that of concrete, but the material weighs much less.

• Water. The main limitation is high water absorption, which reduces mechanical resistance. The review also notes the lack of shared standards for testing these materials.

Regarding fire, precision is needed. Mycelium on its own does not have specific fire-retardant properties, explains a 2020 review by the Technical University of Denmark. It improves them when it grows on substrates rich in silica, such as rice husks. In the tests reported by Alaneme, some mycelium composites had a lower peak heat release during combustion than the polystyrene foam used as insulation.

Where is mycelium used today

Research lists many fields of application: packaging, furniture, acoustic and thermal insulation panels, paper, and textiles. Some are still experimental, others are already on the market.

L-ife grows mycelium on straw and wood waste and shapes it for various uses:

• Customized packaging, designed around the product to be protected;

• displays for shops and points of sale;

• trade show setups for stands and events;

• diffusers and design objects.

In 2025 L-ife won the ADI Packaging Design Award.

Frequently asked questions about mycelium

Is mycelium the root of the fungus?

No. Mycelium is the vegetative body of the fungus, i.e., the organism itself, formed by a network of filaments called hyphae. The mushroom that sprouts from the ground is the fruiting body, the part that produces spores. The comparison with the root is widespread but inaccurate because fungi do not have roots.

What is the difference between mycelium and a mushroom?

Mycelium is the organism that lives in the soil or wood and feeds on organic matter. The mushroom, also called a carpophore or fruiting body, is the structure that the mycelium forms when it matures to produce and disperse spores.

What are mycelium hyphae made of?

The walls of the hyphae are composed primarily of chitin, a polysaccharide, along with glucans and proteins. According to the fact sheets from the European CORDIS program, these components form a fibrous and interconnected network that gives mycelium structural strength and versatility.

What is the largest mycelium in the world?

The most cited case is a specimen of Armillaria ostoyae in the Malheur National Forest, in Oregon. According to the Oregon Encyclopedia, it covers about 965 hectares and, by the highest estimates, could be 8,650 years old. Age is estimated by the speed of the fungus's expansion, so it should be considered an approximation.

What function does mycelium have in a material?

In mycelium-based materials, the hyphae grow between particles of plant waste, such as straw or sawdust, and bind them together like a natural glue. The material takes the shape of the mold in which it grows. Finally, heat eliminates moisture and stops growth, and the material becomes inert.

Is mycelium still alive in mycelium products?

No. According to the review published in 2023 in the Alexandria Engineering Journal, after growth, the material is heated above a critical temperature to remove moisture and stop the organism. The result is an inert and lightweight composite.

Does mycelium insulate against heat and cold?

Yes, according to sector research. In several studies, mycelium composites have a thermal conductivity between 0.05 and 0.07 W/mK, values close to glass wool, which the same review indicates at 0.04 W/mK. Performance varies significantly depending on the fungal species, substrate, and processing.

Is mycelium fireproof?

Not by itself. A 2020 review by the Technical University of Denmark explains that mycelium on its own does not have specific fire-retardant properties, but improves them when grown on substrates rich in silica, such as rice husks. For a specific product, dedicated tests are needed.

If you are considering mycelium for your project, write to us: we can start from your waste product and your needs.