What is Mycelium in Fungi & Mushrooms | Mycelium Network and Definition

Whether you’re generally studying fungi or specifically learning to grow mushrooms, you’ll mostly encounter the term mycelium, mushroom mycelium in fungi, or mycelium pinning.

Mycelium is the vegetative part of a fungus consisting of a network of thread-like filaments—hyphae.

From there, you might find yourself wondering:

1. Do all fungi form mycelium?
2. Do all mycelium form mushrooms?
3. How does mycelium form?
4. What are the functions of mycelium?
   • Also, why is mycelium important in the forest?
5. How do I know about mycelium pinning or forming mushrooms?

Below, we will answer these questions as concisely as we can.

1. Do All Fungi Form Mycelium?

Firstly, fungi can be multicellular or unicellular. Most fungi are multicellular and have two stages: vegetative and reproductive.

The vegetative stage is a period of intensive growth where mycelium seeks out and absorbs nutrients. Then, it enters a reproductive phase by forming fruiting bodies that release vast quantities of spores.

Unlike multicellular fungi, like yeasts, unicellular fungi do not form mycelium. Instead, they reproduce by budding.

Budding is a process where a small bud arises as an outgrowth of the parent body. This process is triggered by a rich supply of critical nutrients such as amino acids, sugars, and nitrogen compounds.

Fungi may produce asexually by fragmentation, budding, or producing spores.

2. Do All Mycelium Form Mushrooms?

Not all mycelium-forming fungi produce mushrooms (a fungus’s fleshy, spore-bearing fruiting body). Fungi that produce mushrooms are primarily members of the phylums Ascomycota or Basidiomycota.

However, it’s not only the mushroom that may produce spores. Spores may be released directly on the somatic hyphae. Further, there are several other types of spore formation.

3. How Does Fungi Mycelium Form?

For fungi that reproduce from spores, mycelium formation is initiated by spore germination. As the spore germinates, it produces a short, initial hypha (called a germ tube).

The germ tube expands and branches. Then, each branch forms new units, and so on. The mycelium (mass of branching hyphae) eventually assumes a circular form by repeated branching.

Although the mycelium expands outward, there can be cross-connections between branches. This allows for quick and easy-to-move nutrients around the growing mycelium.

If you’re a mushroom grower, you most likely are concerned with the type of mycelium growth in your substrate. Experienced growers prefer a specific kind of growth. Which do you think is it?

4. What Are the Functions of Mycelium?

The mycelium has three main functions:

1. seeks out the food source
2. secretes enzymes to break down the food source
3. distribute the nutrients around the colony and eventually to the growing fruiting body

To understand the functions of mycelium, think of it as the root system of a plant. Like plant roots, the mycelium anchors the mushroom. Plus, it absorbs water and minerals, conducts these to the fruiting body, and stores reserved nutrients.

In addition, the mycelium protects itself by secreting enzymes. Such enzymes break down food sources and fight off competing pathogens (like an immune system response).

Why Is Mycelium Important in the Forest?

Aside from mycelium’s function in relation to its fruiting body, it does much more to plants and animals in the forest or life on earth.

In the forest, tree and plant roots are connected through mycelium. This allows trees and plants to send and receive information and nutrients from each other like an underground network.

In addition, mycelium breaks down and absorbs surrounding organic matter. In doing so, they play a critical role in ecosystems’ decomposition and regeneration process.

Without mycelium or fungi in general, the Earth will be a pile of dead matter. Thus, fungi make life on Earth possible, not to mention its ability treat, cure, or prevent diseases.

5. How Do I Know About Mycelium Pinning?

Mycelium Pinning reflects a multi-stage development of mushroom-producing fungi. Primarily, a primordium (sometimes referred to as pinhead) is the earliest identifiable stage of development of a fungus’ fruiting body.

The hyphal knot (center where individual hyphae strands bundle together) is where the pinhead and body of the mushroom first start to sprout. The growth from hyphal knots to pinheads is a process visible to the naked eye.

Literally, pinheads look like tiny white circular pins that will eventually mature into mushrooms.

Usually, pins start to form on the 28th day after spore inoculation. However, this varies depending on the species of fungi and conditions: i.e. substrate type, pH level, humidity, and temperature.

As a recap, we learned that:

• Not all fungi form mycelium, and not all mycelium produce mushrooms.
• Also, mycelium functions like plant roots to seek out and distribute nutrients.
• Lastly, mycelium pinning is characterized by the emergence of white circular pins.

There is still a lot to discuss mycelium in fungi, but hopefully, we have tackled the ones you’re dying to know about.

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