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NatureSpeak Articles

Separate Wood Wide Webs?

Whistler Naturalists volunteers Abbey, Sabrina and Mel identifying a scaley chanterelle at a previous Fungus Among Us, an ectomycorrhizal species of fungi. Photo by: Joern Rohde

In the autumn it’s always fun to see the wide variety of mushrooms popping up. It’s when we celebrate fungi with Fungus Among Us, now in its 19th year. But what are fungi doing the rest of the year?

First a quick review: Mushrooms are to a fungus what apples are to an apple tree—they are the fruiting body, and their purpose is to release tiny seeds (spores) to reproduce. Continuing with the analogy, an apple is quite small compared to the tree, which is the same with mushrooms and fungi.

About half of our fungi are in mutually beneficial relationships with living plants and these are the ones I’m continually fascinated with. These fungi are called mycorrhizal, which means “fungus root”. Amazingly, in a teaspoon of healthy soil there can be kilometres of fungus roots known as mycelium. They attach to or can grow into small feeder roots of plants and help absorb water and nutrients more efficiently. Then, in exchange, the plants provide carbon-based food for the fungi, which they produce through photosynthesis.

Recent studies investigating mycorrhizal fungi found that they transport food from trees between themselves, fungus to fungus, but they can also connect trees together. Scientists like Suzanne Simard from UBC have found that big, old trees are hubs for this massive network which has cleverly been called the wood wide web.

While I love the analogy, consider this: In the world wide web, if you’re on a PC or a Mac we can still all communicate with each other. It turns out that it doesn’t work that way underground. There are two major types of mycorrhizal fungi that form webs which are entirely separate from one another.

The first is endomycorrhizal (endo = inside), which grow inside root cells of plants and form symbiotic relationships with about 85% of plant families. There second is ectomycorrhiza (ecto = outside), which grow on the outside of root cells and forms symbiotic relationships with about 10% of plant families.

What does this mean for our forests? Most trees associate with ectomycorrhizal fungi so in Whistler that means Douglas-fir, spruce, true firs, pines and hemlocks can all talk to each other underground. Interestingly, redcedar and yew are on a separate network since they associate with endomycorrhizal fungi. I’ve wondered if redcedars and yews are at a disadvantage being apart from the rest of the trees but as with all things in nature, I’m sure studies will show that everything will balance out in the end (as long as humans don’t interfere).

There are thousands of ectomycorrhizal species worldwide including chanterelles and truffles. There are only a couple of hundred endomycorrhizal species but they are generalists, meaning that even the few species that exist in nature can link all of the plants on their network.

We wouldn’t have our forests without mycorrhizal fungi. The trees and fungi are in a delicate balance; when one is healthy, so is the other. That’s why mushrooming is best in old growth forests where this balance—decades or hundreds of years in the making—has not been damaged or destroyed.

Learn more at Fungus Among Us this weekend. Virtual ‘Talks with Gurus’ start Friday at 7:00 pm and the ‘Mushroom Display’ Saturday at 2:30 pm. ‘Walk with Gurus’ Saturday morning is sold out. More info at

Written by: Kristina Swerhun


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