Happy Halloween: entangled in webs

Mycelium is ecological connective tissue, the living seam by which much of the world is stitched in relation. 
~ Merwin Sheldrake ~

Imagine walking with me through a beautiful forest glade. Trees arch above, ferns and moss at our feet, understory shrubs at our elbow, and the sun glinting through the branches of redwoods, laurels, and maples. The air is cool and fresh. At this time of year, the quiet is broken only by the occasional call of a raven or the excited chatter of squirrels. We are walking through a green peace.

Yet, the place is jumping. There are hundreds of thousands of leaves above, many times that in redwood needles, all photosynthesizing like mad. It’s autumn, and the fruits of the bay laurels are ripening, turning from bright green to yellow to red to deepest eggplant purple. The unexpectedly tiny cones of the towering redwoods are opening so they can spread their millions of seeds. Big leaf maple leaves are turning vivid yellow, forming a carpet of stars when they fall.  

Lichen is slowly covering bark, which is itself protecting the busy tubes of xylem and phloem. The latter runs rich carbohydrates from photosynthesizing leaves to roots. Xylem siphons water and minerals up to the leaves. The sweet, spicy scent of laurel dominates the other aromatics in the air. Wildlife abounds: beetles, moths, ants, spiders, snakes, chipmunks, squirrels, coyotes, owls, hawks, ravens. Powerful energies all, silently and invisibly — except for the occasional flash or call of a bird — accompanying us on our walk.

But all this richness is relatively calm compared to what is going on under our feet. There, a mound of dirt no larger than your big toe contains billions of microbes and 20 miles of mycelial threads. Roots spread through the soil, picking up water and nutrients. Humic acid and fungal enzymes slowly wear down stone, releasing minerals that are taken up by plants. Fungi are decomposing plant litter and animal life, adding to the organic richness of the soil. Oxygen and water move through soil pores. All of the plants are talking to their neighbors and tending their young through underground communication channels.

Those channels are formed by minute tubular threads much thinner than a human hair. Called hyphae (singular is hypha), they form the filamentous mats of mycelium. A variety of fungi create them, bringing slightly different skills depending on the fungus involved. Mycelium forms vast underground networks that shuttle nutrients and information. The largest known covers 2400 acres in Oregon and may weigh up to 8,000 pounds. Sensitive to light, texture, gravity, moisture, and temperature and able to work around obstacles, mycelium builds rapidly forward at the ends of its billions of hyphal tips. They, in turn, report their findings back to the network.

When fungi and roots get together, they form a symbiotic relationship called mycorrhiza, which combines the Greek words for fungus and root. The relationships differ depending on how the hyphae connect to the roots. Some interpenetrate the root tips, others create nets around them. To reproduce, hyphae pleat together to form mushrooms and send them above ground to ripen and decay, thereby releasing their minute spores into the air and spreading the fungus. The mushrooms accompanying this post — in appropriate Halloween costumes — are all on their way to doing just that.

The fossil record tells us that the earliest land plants — algae migrating from primordial seas — didn’t have roots and depended on a fungal partner to provide them with resources. This partnership didn’t end with the long evolution of roots. Mycelium’s hyphae are much finer than the smallest root hair. Thus they provide much more surface area than roots alone for the transport of minerals and water.  Plants with little or no mycelium are much weaker than those with a thriving network. This is one reason why conventional agriculture, with its drenching fungicides, is so dependent on chemical fertilizers.

Feeding plants and decomposing organic matter to feed soil are crucial tasks. And perfectly understandable. The wild thing about mycelium is its ability to transport information. Forest ecologist Suzanne Simard has shown that if a seedling is struggling because it can’t photosynthesize enough sugars, its parent gets the message and sends some over via their fungal connections. And not just between parent and child; siblings preferentially share carbon, as well. And though family members do the most networking, tree partners of different species will share nutrients when one falls short. Dying plants donate their minerals to living ones. If a plant is beset by insects, it sends out a warning. Nearby plants then increase their production of chemical deterrents. In the process of transporting sugars, water, and minerals to roots, these delicate threads negotiate how much of each is needed and how much to deliver moment by moment.

Mycelium does all this in exchange for the carbon-rich sugars the plant offers through photosynthesis. The fungus thus has every reason to keep all the plants it’s connected to alive and well. Such complete interdependence begs an interesting question: did fungi drive the evolution of plants in order to have a source of food? Are plants basically leafy extensions that fungi send up to photosynthesize? As biologist Merwin Sheldrake points out in his fun and fascinating book, Entangled Life, “it’s hard to avoid the feeling that these fungi have stumbled upon a winning strategy.”

It’s also hard to overstate how much mycelium there is. Sheldrake does some math: if all the hyphal threads in just the top few inches of Earth’s soil were placed end to end, they would span half the Milky Way. Fungal mycelium is crucial to understanding ecosystems because few exist without it. And it may prove to be one answer to our need to remove carbon from the atmosphere. Richly fed on and composed of carbohydrates, mycelium grows wide and deep. By burying carbon it becomes one of our most important carbon sinks. Mapping and preserving mycelium is now an urgent task.

Because of its ubiquity, everywhere we go we are treading on an intelligent underground. Beings that can communicate, transport, find their way from one goal to another along the most efficient route. That can overcome problems. negotiate with other beings, sort through options. That know what is happening at the farthest reaches of their vast network. So far, how they do all of this  remains a mystery, as does so much nonhuman wisdom. 

I would love to know the answers and am also fine without them. Mysterious is the order of the day. It’s delightfully spooky to wander the woods knowing that we are caught in these busy, chattering, wise webs, ever tying the world together. Happy Halloween!

Top photo is the Western Jack-o-Lantern (Omphalotus olivascens) Mount Burdell, Novato, California

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