FIELD NOTES BLOG

Mushrooms, Mycelium, and Fungi Explained

Emma Zimmerman
May 21, 2024

It’s that time of year that budding mycologists and mushroomers alike look forward to! Spring is in full bloom, and mushrooms are appearing in the forests of Northern Illinois. With the emergence of morels and other edible species, mushrooms are on the mind of many, and there is no better time to learn about these elusive organisms!


Fungi have been on the Earth for over a billion years, but they're still not very well understood. Scientific estimates suggest there are between 2.2 and 3.8 million species of fungi in the world, although only about an estimated 10% of them have been identified! Despite their enigmatic nature, ongoing scientific inquiry continually unveils intriguing insights into these organisms. Understanding the pivotal role fungi play in ecosystems requires unraveling the unique characteristics and evolutionary relationships of the truly fascinating fungi. 


Fungi Explained

When considering living organisms, the conventional dichotomy often revolves around plants or animals. Fungi, however, are neither. Like plants and animals, fungi are eukaryotes, meaning that their cells have a nucleus where DNA is stored. This is about where the similarities end though. Unlike plants, fungi lack the ability to perform photosynthesis for energy production, and unlike most animals, fungi do not have stomachs. Instead, fungi typically excrete digestive enzymes to break down materials outside of their bodies, which they can then absorb. Another quality that is unique to fungi is that they have chitin (the same material that makes up an insect's exoskeleton) inside of their cell wall which allows them to grow through hard surfaces like rock and concrete!


 
Mushrooms are the visible reproductive structures of certain members of the Fungi kingdom- think of them like an apple of an apple tree. The actual mushrooms, however, constitute only a fraction of the organism's entirety. The bulk of the fungus is composed of minuscule thread-like structures called hyphae, which grow underground or in wood. Cumulatively, these threads form vast, interconnected networks of hyphae known as mycelium. Mycelium networks can be incredibly expansive. In fact, the world’s largest organism is a honey mushroom network (Armillaria solidipes) that spans 2.4 miles across the Malhuer National Forests in the Blue Mountains of Oregon!


Ecological Services of Fungi:

Mushrooms serve many important ecological roles; they aid in decomposition, nutrient transportation, and carbon sequestration. Revered as nature's recyclers, mushrooms adeptly break down organic matter, from decaying trees to animal excrement. They slowly decompose this material and return its nutrients to the soil, where the nutrients are then transported through the ecosystem. Without fungi, the forest would take considerably longer to regenerate. Organic matter isn't the only thing that mushrooms can break down either! A species of Pestalotiopsis discovered in the rainforests of Ecuador was discovered to even break down plastics and petrochemicals


A crucial, yet often overlooked, service that fungi provide is nutrient transportation. Fungi are well known for their mutualistic relationships with other species, where both parties work together for mutual benefit. In forest ecosystems, many fungal species engage in mutualistic partnerships with plants through their mycelium. The mycelium of fungi species form exterior sheaths around the roots of partner plants, effectively extending their root systems and enhancing their ability to absorb water and nutrients. In return, fungi gain access to the carbohydrates produced by the plants. Remarkably, over
95% of plants form such partnerships with fungi through their roots, highlighting the widespread significance of these relationships. This interconnected network of mycelium has been aptly dubbed the "wood wide web" by German forester Peter Wohlleben, as it is through the mycelium that trees communicate. While ongoing research explores the complexities of these interactions and debates their purely mutualistic nature, certain fungi have demonstrated the ability to send warning signals to plants! One type of fungi was even found to stimulate immune responses in plant communities when individual plants face threats. Next time you’re visiting a forest, as you wander through the trees, take a moment to think about the complex exchanges happening underneath your feet!


Mycelium networks are also crucial
carbon reservoirs of nature, and play a vital role in mitigating accelerated climate change. Through their mutualistic association with trees, mycelium receives carbon from them via the roots, facilitating their growth. Consequently, carbon is sequestered underground within the mycelium, rather than remaining in the atmosphere. This process contributes significantly to the regulation of carbon levels in the environment, underscoring the importance of mycelium networks in the global carbon cycle and climate stabilization efforts.


Anthropological Uses of Fungi

Beyond their ecological functions, fungi have substantial importance for humans as well, spanning culinary traditions, pharmaceutical innovations, and environmental remediation efforts. Despite being initially overlooked due to associations with human skin diseases, fungi have been pivotal in revolutionizing medical practices throughout history. Their contributions to drug discovery and development continue to captivate researchers worldwide. One of the most notable examples is penicillin, derived from fungi in the Penicillium genus. Although the discovery of penicillin may be old news, fungi remain at the forefront of medical innovation.


As mental health awareness continues to gain increasing prominence, fungi are once again being utilized. Psilocybin, a well-known psychedelic compound found in over 100 mushroom species,  has recently garnered attention in The United States. Although previously stigmatized and marginalized during the 1960’s, recent scientific studies highlight psilocybin's potential as a
therapeutic agent for conditions such as major depression, anxiety, addiction, and PTSD. Administered in conjunction with psychotherapy, psilocybin has shown significant improvements for those suffering with these illnesses, including long-term effects and instances of remission, underscoring its potential as a transformative treatment (Severson Dells Nature Center recommends that you speak with a primary care provider when considering treatment options; do not take this as medical advice). 


Another use of fungi that is being explored is mycoremediation. Mycoremediation is a form of bioremediation which uses enzymes produced by fungi to break down pollutants in the environment. Not only is this type of environmental cleanup cost-effective and  eco-friendly, but it is also much more effective when compared to other methods we use today! Recent
scientific research has shown that fungi can degrade toxic and persistent waste materials such as plastics, heavy metals, pesticides, and even polycyclic aromatic hydrocarbons (PAH’s), a class of chemicals that occur naturally in coal, crude oil, and gasoline. Better yet, fungi can actually and convert these pollutants into edible fungal biomass within a few days! Fungi’s ability to persist through five previous major extinction events on this planet just goes to show their powers of remediation, and how much we have yet to learn from them.


Fungi Conservation Challenges and Perspectives

Despite their ecological and societal significance, fungi remain largely overlooked in conservation efforts, with negligible representation in regulatory frameworks. Notably, the U.S. Endangered Species Act currently does not specifically mention fungi, and the International Union for Conservation of Nature’s Red List of Threatened Species currently includes a mere 551 species of fungi, compared to the tens of thousands of plants and insects listed  While there is a growing interest in fungi, particularly among conservationists, efforts remain disproportionately focused on fungal pathogens, such as chytrid fungus in amphibians and white-nose syndrome in bats, as opposed to ecologically beneficial species, highlighting the need for greater awareness and advocacy. 


While it can be challenging to motivate people to care about something that seems to be a common sight, especially considering the limited understanding of these organisms among scientists, there is hope for future fungal conservation efforts. Recent milestones, such as Chile's inclusion of fungi in environmental legislation, signal progress towards recognizing and safeguarding fungal biodiversity. Collaborative endeavors spearheaded by organizations like the IUCN Fungal Conservation Committee offer hope for amplifying fungal conservation efforts and fostering broader recognition of their invaluable contributions to our planet's well-being.


RECENT ARTICLES

By Bruce Muench April 25, 2025
Forward:
By Rowan Mermel April 23, 2025
“Once you see it you can’t unsee it”
April 22, 2025
From the rugged peaks of the Rocky Mountains to golden desert canyons, the rolling prairies to the ancient, mist-shrouded Appalachian mountains — America is a land rich in many beauties. We are home to the towering redwoods of the west coast, sun-drenched coastlines in the south, and the deep blues of the Great Lakes that collectively hold the largest volume of freshwater on Earth. These wild places offer a kind of quiet that stirs the soul. This vast, varied land is what we proudly call “America the Beautiful.” And on Earth Day, this is the America we celebrate. We scroll through snapshots of National Parks, photos of mountain trails, canyon vistas, tidepools, and wildflower filled prairies. Maybe we've seen these places with our own eyes — maybe we carry them like a dream we hope to one day reach. We’ve all, in some way, been struck by the beauty of this land. As I write these words, I’m sitting at my desk looking out the window into the woodland of Severson Dells, watching the first green buds emerge, listening to the fluting whistles of returning songbirds. How lucky are we to live among such beauty? But that beauty is in danger. Today, mountaintops in Appalachia are being blown apart for coal, their peaks stripped and valleys buried in rubble. Ancient forests in the Pacific Northwest are leveled for lumber, their centuries-old trees felled in minutes. Oil rigs rise like metal skeletons in Alaska’s fragile tundra, while pipelines thread through sacred Indigenous lands and important wildlife corridors. Wetlands that once buffered our coastlines from hurricanes are drained and filled. Prairies, once stretching unbroken across the heart of the continent like an ocean of grass, are disappearing under pavement and plow. Our coastlines are receding. Our coral reefs, once vibrant, are dying, bleaching bone-white. Even here, outside my window, invasive honeysuckle strangles the understory where spring ephemerals once bloomed, and the chorus of birds is quieter than it used to be — a stark reminder that nearly one-third of North American bird populations have vanished in the past fifty years. But this isn’t a new story. Ours is not the first generation to witness the cost of ‘progress’. The tension between beauty and destruction has shaped this nation since the Industrial Revolution. And while the challenges we face today are daunting, they are not insurmountable. Every year, on April 22nd, we celebrate Earth Day – a day that itself was born from a moment not unlike our own. America of the 1950’s and 60’s is almost unrecognizable from the America we know today. In 1943, Los Angeles residents awoke one morning to skies so dark and chemical-laden they feared they were under a gas attack . It was smog. Just 5 years later, a lethal blanket of smog from zinc smelters in Pennsylvania killed 20 people in just three days . The Merrimack River in New Hampshire ran a different color each day , depending on what the local mills were dumping. And in 1969, Cleveland's Cuyahoga River — thick with oil and industrial waste — burst into flames , its smoke billowing four stories high. These weren’t isolated incidents. They were the symptoms of a larger crisis—one brought on by decades of industrial expansion with few, if any, environmental safeguards. At the same time that America was enjoying unprecedented prosperity, it was also polluting its air, poisoning its rivers, and sickening its people. The economy boomed, but the environmental consequences were growing harder to ignore. In 1962, a marine biologist named Rachel Carson published Silent Spring, a book that would become a cornerstone of the modern environmental movement. Carson’s work focused on the effects of chemical pesticides—especially DDT—on ecosystems and human health. She warned of a future without birdsong, where toxins accumulated in the food chain and sickened both wildlife and people. Silent Spring struck a chord. It didn’t just present scientific facts, it gave voice to a deep, growing unease. People were already noticing the changes around them: the absence of fireflies in summer, the increasing number of fish kills in local lakes, the haze that lingered over cities for days. Carson’s words helped connect the dots, and it didn’t just inform, it inspired, and from it spurred the beginning of the environmental movement. By the late 1960s, a wave of activism was sweeping the country. Young people were leading protests against the Vietnam War, civil rights leaders were marching for justice, and college campuses had become hotbeds of political energy. Watching this cultural shift with inspiration was Senator Gaylord Nelson of Wisconsin. A long-time advocate for environmental protection, Nelson saw how the antiwar movement had galvanized young people—and he wondered whether that same passion could be channeled into fighting a different kind of crisis: the growing threat to America’s air, water, and land. His sense of urgency only deepened in early 1969, when tragedy struck the California coast. A blowout at a Union Oil drilling platform off the coast of Santa Barbara spilled nearly 100,000 barrels of crude oil into the Pacific Ocean . Black sludge washed up on miles of pristine beaches. Seabirds lay dying under slicks of oil. Dolphins and seals washed ashore. The air reeked of petroleum for weeks. The images were devastating—and they were broadcast into homes across the nation. Senator Nelson knew the time to act was now. In November of that year, he announced plans for a "National Teach-In on the Crisis of the Environment" —a day when Americans would come together to learn, protest, and push for meaningful environmental change. This name was later changed to Earth Day, and the date chosen was April 22, 1970—strategically placed between spring break and final exams to ensure strong participation on college campuses.  To bring this ambitious vision to life, Nelson turned to Denis Hayes, a 25-year-old student activist. With Hayes’ help, a 7 month timeline, and a shoestring budget of just $124,000, Earth Day sparked an unprecedented nationwide movement. College campuses began planning teach-ins and events. Newspapers picked up the story. Civic groups, churches, and schools joined in. The momentum built quickly—and organically. Within a few months, the Earth Day idea had become a nationwide grassroots event supported by millions of people. Colleges campuses across the country organized “teach- ins”, and major newspapers were writing about Senator Nelson's ideas. Earth Day may have been Gaylord Nelson’s idea, but American citizens made it happen. “Earth Day worked because of the spontaneous response at the grassroots level,” reflected Gaylord Nelson. “It organized itself.” Historian Adam Rome would later call it “the most famous unknown event in modern American history.” On April 22, 1970, an estimated 20 million Americans—nearly 10% of the U.S. population at the time —participated in what remains the largest single-day political demonstration in the nation’s history. People from all walks of life gathered for marches, cleanups, rallies, and teach-ins. The message was clear: the environment mattered, and the public was ready to fight for it. What made Earth Day so powerful was not just its scale, but its unity. The movement crossed ideological lines. It was bipartisan, supported by both Democrats and Republicans. At a time of deep national division, Earth Day reminded Americans that the health of our planet is a shared responsibility—and a common cause. Even more remarkable is that this enormous, coordinated event was pulled off without the tools we rely on today. No social media. No email. No cell phones. Just passionate people, printed flyers, rotary phones, and the belief that change was possible. The success of Earth Day didn’t just move the public—it resonated with leaders in Washington, and led to real change. In just a few years, the United States went from having almost no federal environmental policy to enacting an environmental policy infrastructure strong enough to slow down the era of unregulated industrial sprawl to protect our planet and public health. The success of the first Earth Day led to the passage of some of the most important environmental legislation in American history, including: The Clean Air Act (1970) The Clean Water Act (1972) The Endangered Species Act (1973) President Richard Nixon oversaw the establishment of the Environmental Protection Agency and signed the above landmark environmental laws into effect. In a 1970 speech, Nixon captured the spirit of the moment with a message that still rings true today: “The great question of the seventies is, shall we surrender to our surroundings, or shall we make our peace with nature and begin to make reparations for the damage we have done to our air, to our land, and to our water? Restoring nature to its natural state is a cause beyond party and beyond factions. It has become a common cause of all the people of this country. It is a cause of particular concern to young Americans, because they, more than we, will reap the grim consequences of our failure to act on programs which are needed now if we are to prevent disaster later. Clean air, clean water, open spaces—these should once again be the birthright of every American. If we act now, they can be. We still think of air as free. But clean air is not free, and neither is clean water. The price tag on pollution control is high. Through our years of past carelessness we incurred a debt to nature, and now that debt is being called. ” In the years that followed the first Earth Day, America made progress—rivers stopped catching fire, cities began to breathe a little easier, and wildlife rebounded. But the work was never meant to end in the 1970s. Earth Day is a reminder that the environment is not a limitless resource, and that protecting it requires action, accountability, and cooperation. Fifty five years later we face new environmental challenges, but Earth day is a reminder of what we can accomplish when we come together, regardless of party or background, to protect the natural world we all share. Today, the landmark pieces of legislation that were established in the 1970’s are under threat. The first hit to the Clean Water Act was the U.S. Supreme Court’s 2023 decision in Sackett v. EPA, which significantly narrowed the Act's scope, limiting protections for wetlands and many streams. This ruling has led to a significant weakening of federal oversight. More recently, the EPA has announced significant changes to the Clean Water Act that potentially puts the drinking water sources for tens of millions of Americans at risk. As for the Endangered Species Act, there is a proposed rule change that would limit violations of the Act only to actions that hurt or kill animals. Harming the habitats the endangered animals need to survive would no longer be a violation of the Endangered Species Act, which would open large swaths of land to logging, mining and development that were previously protected. As we all know, if a species doesn’t have the habitat to survive and breed in then it will eventually go extinct. This proposed rule change is open for public comment until May 19 in the Federal Register, so please consider sharing your opinion . Additionally, there is the Zero-Based Regulatory Budgeting To Unleash American Energy Executive Order. The legal community is still trying to figure out just how far reaching this EO is, but it is likely to have a significant impact on a wide range of environmental regulations. These threats to the health of our environment put “America the Beautiful” at risk. The spacious skies, amber waves of grain, purple mountain majesties, and the fruited plain from sea to shining sea are left vulnerable. Now more than ever, Earth Day calls on all of us to act to protect our beautiful environment. Earth Day is now celebrated in over 190 countries. But its roots lie in a time when people refused to accept the destruction of the world around them as inevitable. So, what will you do this Earth Day? Because history has shown us: when people care, when they act together, the world changes. The debt to nature is still being called—and we still have the power to answer. This Earth Day, don’t just celebrate – participate. Plant a tree. Call your representatives. Learn the name of the bird outside your window. Donate to organizations that support our natural lands, our water, and our future. Vote. Teach your children not just to love the Earth, but to fight for it. Talk about climate change, even when it’s hard. Especially when it’s hard. Use your voice, use your art, use your science. Join a local cleanup, start a compost bin, reduce your plastic use. Talk to your neighbors. Talk to your parents. Talk to your children. You can’t wait for someone else to take action. You don’t need to be perfect. You don’t need to do everything. But you do need to begin. Because the Earth doesn’t need more perfect people, it needs millions of imperfect people who care enough to act with intention everyday. Sources: Klein, Ezra, and Thompson, Derek. Abundance . Simon & Schuster, 18 March 2025 “Gaylord Nelson & Earth Day Origins.” Nelson Earth Day , https://nelsonearthday.net/gaylord-nelson-earth-day-origins/ . Accessed 18 Apr. 2025. Gammon, Katharine. “The Deadly Donora Smog of 1948 Spurred Environmental Protection—But Have We Forgotten the Lesson?” Smithsonian Magazine , 26 Oct. 2018, https://www.smithsonianmag.com/history/deadly-donora-smog-1948-spurred-environmental-protection-have-we-forgotten-lesson-180970533/ . Accessed 18 Apr. 2025. Lamoreaux, Naomi. “The 1943 Hellish Cloud Was the Most Vivid Warning of L.A.'s Smog Problems to Come.” Smithsonian Magazine , 15 Jan. 2018, https://www.smithsonianmag.com/smart-news/1943-hellish-cloud-was-most-vivid-warning-las-smog-problems-come-180964119/ . Accessed 18 Apr. 2025. “The Merrimack River: How Revisiting Its History Helps Renew Action.” Forest Society Blog , Society for the Protection of New Hampshire Forests, 26 Sept. 2022, https://www.forestsociety.org/blog-post/merrimack-river-how-revisiting-its-history-helps-renew-action . Accessed 18 Apr. 2025. Pyne, Stephen J. “The Cuyahoga River Caught Fire at Least a Dozen Times, but No One Cared Until 1969.” Smithsonian Magazine , 22 June 2019, https://www.smithsonianmag.com/history/cuyahoga-river-caught-fire-least-dozen-times-no-one-cared-until-1969-180972444/ . Accessed 18 Apr. 2025. Westervelt, Eric. “How California’s Worst Oil Spill Turned Beaches Black and the Nation Green.” NPR , 28 Jan. 2019, https://www.npr.org/2019/01/28/688219307/how-californias-worst-oil-spill-turned-beaches-black-and-the-nation-green . Accessed 18 Apr. 2025.