Field Notes
~ by Jim Eagleman
Lessons from fungi
Years ago, I struggled through a class in agriculture economics. Supply and demand I understood, but not trading, global reliance, and stock markets. When a botany professor on a walk explained how fungus grows and told us to imagine it as a market economy,“ one that was 400 million years old, and so universal that it operates in almost every ecosystem in the world,” his analogy got me thinking.
He said unlike human economics requiring understanding and reasoning to help make decisions,“ traders in this market beg, borrow, steal, and cheat all without thought.”
I wanted to know more about this biology, and it took some study. And funny thing: a lesson in one discipline can help you understand another.
I learned that the intertwining plant roots of all kinds of trees, shrubs, and wildflowers, are colonized by the fungus mycorrhizae. Fungus forms these underground, vast, and complex networks. They are tiny filaments, thinner than a strand of cotton, and are connected to multiple plants simultaneously. A tiny underground subway system was another comparison I was to visualize, where each plant root is a station, and resources are loaded and unloaded.
A mushroom poking up through the leaf litter, sometimes colorful and exotic-looking, is not the actual plant, but the fruiting body. As nutrients
58 Our Brown County • May / June 2025
are absorbed and the fungus grows, sometimes just within minutes, spores develop that can produce more mushrooms. I thought of spores as specialized seeds— tiny, encapsulated, and wind-swept, capable of withstanding droughts, freezing, and time. They grow when conditions are right.
I read of an archaeologic dig at the pyramids where workers excavated gravel from deep within the tunnels. The dirt and stones were carried out daily and dumped outside the pyramid, then covered with a tarp. The work continued for weeks, and one day mushrooms grew on the debris pile. Enough heat, wind or moisture, or combinations, had accumulated, causing spores to grow a new mushroom. They were identified as the same mushrooms that grew locally from spores that were estimated to be 4,500 years old.
He said deals made by plants and fungal partners can be similar to those made by stock market traders. These partners are not exchanging stocks and bonds, they’ re exchanging essential resources. For the fungus, that’ s sugars and fats. The fungus gets all its carbon from the plant— a lot of carbon from a lot of plants. How much carbon? It’ s estimated that each year, roughly five billion tons of carbon from plants go into this underground network. Roots need phosphorus and nitrogen, and get it from exchanging carbon to gain access to all the nutrients collected by the fungal network. This exchange we were to think of as the actual stock exchange of the trade market.