Mushroom of the Week: Wood Wide Web


There has been a lot of talk lately in the news about how plants, trees and fungi can communicate with one another and transfer nutrients back and forth in times of need, or perhaps, in just the normal course of doing business.

A term 'The Wood Wide Web' was generated 25 years ago in Nature magazine to describe just such a relationship.  The vast network of thread-like mycelia that fungi produce in the soil wrap themselves around, and even inside, tree and plant roots and enable the transfer of water and nutrients in all directions.  

In fact, the mycelia, which you can often see under the bark of a rotting tree or in the soil near a mushroom, is the fungi organism itself.  The mushrooms are just the fruiting bodies that pop up from time to time and, if we’re lucky, they’re quite edible too.

I grew up being told to be afraid of mushrooms and to stomp on them if I saw them while mowing the lawn.  I was told they killed the trees and grass and were mostly all poisonous.  In fact, nothing could be further from the truth.  I was also told that trees were healthy because they had a huge root system with little rootlets that had bacteria which allowed them to get nutrients out of the soil.  That too could not have been much further from the truth.

The reality is that tree roots are quite poor at getting water and nutrients out of the soil.  They make for a good anchoring system, but it is the fungi that provide trees with the nitrogen, phosphorus, potassium and other nutrients that they need due to the vast network of mycelia which comprises them.  These mycelia wrap around and penetrate tree root hairs, creating minute structures within them to effect nutrient transfer.  In return for receiving up to 80 percent of the minerals they need, trees provide the fungi with around 30 percent of the sugars they produce in a given year.

The vast underground mycelial structure of the fungi provides a network for trees to absorb water and is essential for forests to survive droughts.  Some flora, such as pines and orchids, the largest group of flowering plants in the world, are completely dependent on the existence of fungi.  Without them, they simply could not grow.

It is also surprising that 95 percent of all trees, plants and grasslands have some sort of fungal relationship and the vast majority of those fungi, believe it or not, never produce mushrooms at all.  They live their lives completely underground.  Maples, olive trees, most fruit trees, vegetables and berries have relationships with fungi that never produce fruiting bodies.

Suzanne Simard was the first to prove that completely different species of plants actively transfer nutrients to each other through the vast network of mycelia that fungi create in the soil.

The study of the Wood Wide Web began in British Columbia where it was proven that firs and birch trees, two completely different species, transferred essential carbon back and forth to each other.  Whether you could call this helping each other, or not, is left up for debate but these parallel systems of mineral transfer do provide benefits that both species can use.

Carbon, the essential element in sugar, is key to this whole system.  It gets transferred from fir trees, which are photosynthesizing all year around and producing sugars, to young birch trees who are often growing beneath the shade of tall firs.  As the summer proceeds and the birches leaf-out, the flow of carbon goes from birch back to the firs.  

Studies in Québec showed that a flower, the Trout Lilly, which produces leaves very early in the spring, shares carbon with young maple saplings who produce leaves late in the spring and are heavily shaded by mature maples.  In the fall, the maples share carbon back to the lillys which assists them in their root development, essential for the following years growth.

One can think of the Wood Wide Web as a huge, hippy-dippy, peace-and-love relationship between various species acting in the soil, or you could view it as the movement of minerals and nutrients in a vast and complex network mediated by multiple independent mycelial networks.

Take your pick.  But for now, know that all this is happening below your feet and take a longer look at the next mushroom you see.

Recommended readings on this topic are ‘The Hidden Life of Trees’ by Peter Wohlleben, ‘Mycorrhizal Symbiosis’ by Smith & Read, ‘Entangled Life’ by Merlin Sheldrake, and ‘Finding the Mother Tree’ by Suzanne Simard.  I will be offering a talk on this via the Manchester Public Library later this winter.

Gary Gilbert lectures about fungi locally and through the Boston Mycological Club.  Some of his recipes will be featured in the soon to be released Fantastic Fungi Community Cookbook, a compendium of recipes from myco-chefs throughout the country.

the wood wide web, the hidden life of trees’ by peter wohlleben, ‘mycorrhizal symbiosis’ by smith & read, ‘entangled life’ by merlin sheldrake, and ‘finding the mother tree’ by suzanne simard, gary gilbert