Mushroom mycelium… the underground network that connects and supports all life.

Threads of mycelium spreading across the surface of a dead or dying tree, where the bark has fallen away.

When we see mushrooms in nature, we witness forms and shapes that are very different from the everyday button mushroom of picture books.

And honestly, mushrooms look strange at the best of times. Not like any plants we know. No leaves or flowers. No seeds even.

It’s as if they’re from an oddly alien kingdom, with their caps, smooth skins and spores.

But things get stranger.

Mushrooms are simply the reproductive structure, or fruiting body of mycelium.

Next time you pick a mushroom from the ground, pause and consider what lies beneath.

And keep in mind that the mushroom represents a very, very small part of the larger organism.

The mushroom is simply the fruit of mycelium.

Mycelium is a vast fungal network that is woven through the soil under every step we take.

And underneath each step – almost anywhere in the world you walk - there are up to 300 miles of fungal mycelium.

What does mycelium look like? On a wet day in the fall, if you pick up a layer of wet leaves, or move a fallen, rotting branch, you might see a web of white or almost white threads spreading across the ground. What you’re seeing is mycelium.

It’s everywhere, and these networks can be huge.

In fact, the world’s largest and oldest organism is an unbroken network of mycelium, sometimes referred to as the “Humongous Fungus”.

It’s a living organism that covers almost 4 square miles in the Malheur National Forest in Oregon. It's estimated to be over 8,500 years old!

Mycelium does a great deal more than simply grow and spread.

Mycelium is a worldwide web… but organic and always growing and changing.

It holds soils together and helps aerate them. It actually creates soil by excreting acids and enzymes that break down organic matter and even rock.

Saprophytic mushrooms and their mycelium networks use those acids and enzymes to decompose fallen leaves, plants and trees. Not to mention dead animals, insects and birds. They break everything down into simpler molecules that become part of the broader ecosystem.

Fungi are the world’s primary decomposers. Without them the planet would be overwhelmed with piles of dead organic matter. Imagine if every tree that had ever fallen over the last million years was still there on the ground… fallen but unchanged.

We’d be miles deep in fallen wood.

But fungal mycelium decomposes all the organic detritus on the ground and transforms it into soil.

Mycelium partners with and supports almost all plants and trees.

In addition to being decomposers, woven into the nutrient cycles of the planet, mycelium is also a communications and transport network.

Sounds crazy, but it’s true.

One simple example of this is the extraordinary symbiotic relationship that exists between mycorrhizal fungi and trees.

Mycorrhizal fungi actually penetrate into the walls and cells of a tree’s roots. It does the same with plants.

Now there’s a physical connection between the roots and the mycelial network, valuable exchanges can take place.

A microscopic view of the thread-like hyphae that make up mycelium.

The mycelium extends far beyond the reach of a single tree’s roots, so it can access minerals and other nutrients that can’t be reached by the tree.

The mycelium passes these nutrients on to the tree.

But it gets something in exchange.

Trees and plants create carbon and sugars through the process of photosynthesis.

Mushrooms and mycelium can’t do that.

So, in exchange for the nutrients the mycelium passes on to the trees, the trees give back their excess carbon and sugars.

It’s an extraordinary relationship.

Mycorrhizal fungi will even create connections between parent trees and their offspring, allowing the “mother tree” to pass on nutrients to the younger trees.