Without this one thing, every single thing you know and love would disappear. Soil would fail, forests would starve, antibiotics would, well, vanish, and your morning coffee, bread, beer, and even chocolate would be gone.
The thing I’m talking about is everywhere. It’s probably in your lunch. It’s almost certainly in your lungs. It’s in your sourdough starter, your compost heap.
Got a clue yet?
Most people don’t actually know what these things are.
I’m talking about fungi. Fungi are not plants, not animals, not bacteria — they’re something else entirely. And they’re really, really old.
They’re older than dinosaurs, older than sharks — they might even be older than plants, depending on how you define a plant.
Today, I’m diving into something I’m actually violently allergic to: fungus. I’m covering everything from what fungi actually are (because it turns out most of us have no idea) to why they might be the most important thing on Earth… ish.
Sources:
Billion-year-old fungal fossils (Nature 2019): https://www.nature.com/articles/s41586-019-1217-0
Armillaria “humongous fungus” 9 km² individual: https://www.scientificamerican.com/article/strange-but-true-largest-organism-is-fungus/
Prototaxites 8 m Silurian-Devonian giant: https://www.science.org/content/article/ancient-giant-fossils-may-be-world-s-oldest-known-terrestrial-fungi
90 % of plants with mycorrhizae (Nature Scitable): https://www.nature.com/scitable/knowledge/library/an-ecological-and-evolutionary-perspective-on-mycorrhizal-24286790/
Mycorrhizal carbon sink 3–7 Gt CO₂ yr⁻¹ (Science 2022): https://www.science.org/doi/10.1126/science.abf3457
Penicillin discovery background (Nobel Prize): https://www.nobelprize.org/prizes/medicine/1945/fleming/facts/
Statins from Penicillium citrinum (review): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5958453/
Cyclosporine discovery story: https://pubmed.ncbi.nlm.nih.gov/7568434/
Psilocybin phase-II depression trial (JAMA Psychiatry 2021): https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2787297
Plastic-eating fungus Pestalotiopsis microspora (2011 study): https://pubmed.ncbi.nlm.nih.gov/22269855/
CDC overview of Candida auris drug resistance: https://www.cdc.gov/fungal/candida-auris/
Chytrid fungus amphibian decline paper (Science 2006): https://www.science.org/doi/10.1126/science.1125069
Mycoremediation and mycofiltration review (Biodegradation 2018): https://link.springer.com/article/10.1007/s10532-018-0914-8
Kia ora, kaitiaki, and welcome to Now That's What I Call Green. I'm your host, Brianne West—an environmentalist and entrepreneur trying to get you as excited about our planet as I am. I'm all about creating a scientific approach to making the world a better place, without the judgement, and making it fun. And of course, we’ll be chatting about some of the most amazing creatures we share our planet with.
So, if you’re looking to navigate through everything green—or not so green—you’ve come to the right place.
Without this one thing, every single thing that you know and love would disappear. Soil would fail, forests would starve, antibiotics would—well—vanish, and your morning coffee, bread, beer, and even chocolate would disappear.
The thing I'm talking about is everywhere. It's probably in your lunch. It's almost certainly in your lungs. It's in your sourdough starter. Your compost heap. Are you getting a clue yet?
And yet, of course, most people don’t actually know what these things are.
I’m talking about fungi.
Fungi are not plants. They’re not animals. They’re not bacteria. They’re something else entirely—and they’re really old. Older than dinosaurs. Older than sharks. In fact, they might be older than plants—depending on your definition of plant.
Kia ora, I’m Brianne, and welcome back to Now That’s What I Call Green.
Today, I’m going to talk about something I’m actually violently allergic to: fungus. I’m going to cover everything from what fungi actually are—because it turns out most of us have no idea—to why they’re the most important thing on Earth... ish. They prop up the backbone of life—and they might help us solve all the problems we’re causing.
If you’re interested in fungi and want more, or you just like stuff that’s a bit creepier and a bit shorter because TikTok has ruined your attention span, later in the week the microgreens version will be up—which is all about zombie fungus. Because why not?
So, welcome to Fungi 101.
Let’s start at the beginning. Life’s beginning, as it were.
So, talking about 1.5-ish billion years ago, give or take—there was life at that point. It was mostly single cells, which we call prokaryotes, and they were just bobbing about in the ocean. The ocean was, obviously, chemically quite different to what it is now. But it was about then that the tree of life split into some pretty big branches.
One led to animals, another to plants, and another became fungi.
Fungi are something called eukaryotes, which are organisms that have more complex cells. So, they contain a nucleus and internal compartments. You are a eukaryote. In contrast, prokaryotes—the single-celled ones I mentioned earlier—that’s bacteria and archaea.
Now, depending on where you were educated as a kid, you might think there are four, five, six, or even seven kingdoms of life. I’m not here to argue about it. That’s what I was taught, and that’s what we’re going to use today.
Prokaryotes don’t have a nucleus. They don’t have internal membranes. They’re quite a lot simpler. Eukaryotes are pretty much everything else that you’re familiar with—fungi, animals, plants—you name it.
That means, of course, that fungal cells have a lot more in common with ours than they do with, say, an E. coli cell.
And even more interestingly, fungi are more closely related to us than to plants. Which surprises people—but we actually share more DNA with a mushroom than with a fern. Certainly, some people look like they do.
Scientists believe this is because the plant lineage branched off first, and then later, the branches that eventually became fungi and animals—as we know them—split from each other. Or from our last common ancestor, if you like. So fungi and animals are slightly closer relatives. I guess it just means we hung out a little longer on the same evolutionary path.
Both fungi and animals store energy as glycogen—which you may have heard of—while plants use starch. We build our cell membranes with similar kinds of sterols (fat-like molecules—you’ll have heard of cholesterol, of course), and they help keep cell membranes stable and flexible. Plants use entirely different molecules.
And, of course, a big one: fungi don’t photosynthesise.
Like us, fungi are something called heterotrophs. This means they don’t make their own food the way plants do—they have to consume other organisms to survive.
So instead of harvesting sunshine through photosynthesis, they are more into rot, I guess.
Fungi primarily feed by excreting digestive enzymes into whatever they’re on—whether it’s wood or soil or whatever—and then they dissolve it into some kind of delicious soup, I suppose, and absorb those nutrients. Not entirely dissimilar to the way some spiders eat. So... oh. That’s an image I didn’t need for my morning.
Now, of course, when most people hear “fungus,” you picture a mushroom, right? But that’s just the tip—literally. Mushrooms are what you call the fruiting body—they’re the spore delivery bits. Which sounds gross.
The real body is actually the mycelium, which is like a massive underground web of thread-like cells called hyphae. People often compare it to tree roots, but that’s a bit too simplistic. Roots are just there to anchor a tree and feed it. Mycelium? Yes, it feeds the organism, but it also senses things. It communicates. It trades nutrients. And—somewhat horrifyingly—it even manipulates its environment.
Rather than roots, it’s like the brain, the bloodstream, the logistics system all rolled into one. And it’s this mycelium that spreads under forests, linking trees and plants and allowing everything to communicate in what some scientists have called the “wood wide web.” They’ve written several books about it—it’s legitimately kind of creepy, kind of fascinating, kind of amazing.
Turns out, plants talk way more than you think they do—courtesy of fungus, of course.
Some fungi are microscopic—you’ll be familiar with yeast. They’re single-celled fungi, but still eukaryotes. So don’t make the mistake of thinking that prokaryotes are all single-celled and eukaryotes are all multicelled. It’s the type of cell that matters, not whether it joins up with others.
Some fungi, on the other hand, are enormous. There’s a fungus in Oregon that’s thought to be about two and a half thousand years old—and it’s nine square kilometres. Depending on your definition, it’s the largest living organism on the planet. Some people say coral reefs are. I’m not interested in the argument—it’s still fascinating.
We haven’t given it a name, strangely, but for some reason they’ve called it the “humongous fungus,” because I guess there’s at least one fungal scientist out there who has a sense of humour.
As I mentioned at the beginning, they’ve been around for a very, very long time. Fossil records show fungal life on land well before plant life made it up here. In fact, some of the earliest, largest terrestrial organisms were fungus.
For example, there’s something called Prototaxites—I probably should have practised saying these before I recorded this podcast, but hopefully that’s how you say it. Any fungal scientists—the technical term is mycologist—feel free to get mad at me in the comments.
Prototaxites were giant tree-trunk-like fungal structures that stood about eight metres tall—but nobody has any idea why.
Without fungus, plants almost certainly would never have made the leap to land. They didn’t have roots at that point. Fungi helped them absorb nutrients from the soil—and that relationship never ended. How sweet.
About 90% of all plant species today still have some kind of relationship with fungi in the soil—whether it’s swapping sugars for minerals or some other symbiotic behaviour. That relationship is called mycorrhiza—but I’ll come back to that.
So fungi aren’t plants, they’re not animals, they’re not bacteria—they’re a whole other kingdom of life, with their own evolutionary path, biology, and weirdness. They’re just weird.
If we go back about a billion years, that’s where we’ve found the oldest confirmed fungal fossils. They were tiny, lived in the sea, single-celled eukaryotes, quietly recycling the organic ick in the primordial ocean—long before anything had a spine or a stem.
Some researchers think fungi may be older—but a billion is the safe bet for now.
Fungi made that move onto land about 600 to 700 million years ago, and they didn’t grow mushrooms back then. They helped form the very earliest soil—which they’ve called biological soil crusts. Sounds legitimately disgusting. These were living skins of microbes that stabilised dirt, locked in moisture... sounded very “beauty editor,” didn’t it?
Because if you can imagine, the Earth back then without soil was just rock—hard and miserable. Not exactly conducive to happy plant life. It was only their colonisation that made it possible for plants to join them.
And by about 500 million years ago, they were teaming up—forming that relationship called mycorrhiza. Essentially, fungi became their early root system. They helped absorb nutrients and water. In return, the plants gave fungi sugars.
That’s called symbiosis—where two different organisms have a mutually beneficial relationship. And as I mentioned, that still happens in the vast majority of plant species today.
Fungi got very good at rot over that time. They are classed as decomposers—organisms that break down dead organic material into simpler compounds. This is essentially what composting is.
They dissolve or consume things like dead wood, leaves, insects, and... dead things. The reason fungi are so good at this is that they produce really powerful digestive enzymes that will break down almost anything—tough substances like lignin in wood or chitin in insect shells. Or yes, probably the most famous example—radiation.
There is a black fungus growing in the basement of Reactor Four in Chernobyl, which is consuming the radiation from the most radioactive object on Earth—“the elephant’s foot”—which is basically the remnants of the melted reactor. That is really quite remarkable.
A couple of weeks ago, we did a mini-series on nuclear energy, and one of those episodes was devoted to radiation—what it actually is. So if you listened to that, you’ll understand how amazing it is that an organism can cope with that level of energy and DNA-shredding potential... and thrive.
We’ll come back to why that’s useful.
And if we didn’t have decomposers like fungi, nutrients would pile up in dead things. All of the stuff we need to grow—nitrogen, carbon—all of it would be locked up in dead material. Eventually, everything would grind to a halt and we’d all die. And also, of course, we’d be knee-deep in dead stuff on the way there.
So, all in all—really quite important decomposers. And probably something you don’t thank your friendly neighbourhood mushroom for enough.
There are multiple groups within the fungal kingdom, and each had its own evolutionary path and niche. A niche simply means where an organism fits within its ecosystem—what its job is.
Yeasts, for example, are single-celled fungi that evolved from multicellular ancestors—so they went from multicellular back to single cells. They’re brilliant at fermenting sugars, which is of course why we use them to make bread and beer—but also drugs. More on that soon.
Then came moulds. You’ll probably be most familiar with these because they grow as fuzzy, fluffy mats. This is the stuff that ruins your bread. So, fungi giveth with one hand and taketh with the other.
Of course, mould gave rise to penicillin—and therefore, future antibiotics.
Next are parasitic fungi—where things get a bit creepy. These invade living organisms, siphon off nutrients, and often kill their host in the process. They infect everything from plants to animals to other fungi.
There’s a very famous example, and if you’re a fan of zombie movies, you’ll know the name: cordyceps. The so-called zombie fungus from The Last of Us. And this is actually what the separate microgreens episode is all about—because it’s really interesting. So watch out for that later in the week.
A particularly bad example is Batrachochytrium dendrobatidis. That’s a chytrid fungus wiping out amphibian populations worldwide. Amphibians, of course, being frogs.
It’s very sad. Frogs are a little bit like the canary in the coal mine for unhealthy ecosystems. And we are spreading this chytrid fungus, of course, with freight, travel, and everything else going on. So this global pandemic of fungus for our froggies is very much our fault—as always.
Lichen-forming fungi are a whole separate thing. They’re like photosynthetic partners, if you like. They partner with algae or cyanobacteria—which is a type of bacteria that can photosynthesise like plants—and are thought to be some of the oldest life forms on Earth.
The fungi team up with the algae or cyanobacteria to form a cooperative organism. Picture it a bit like coral. That combination can survive in extreme conditions—deserts, rock faces, Antarctic soil. They are tough. That’s why you find them on your roof and probably can’t get rid of them.
Then you’ve got hunting fungi—yes, predatory fungi—which use sticky nets or constricting rings to trap microscopic prey like nematodes. It’s fascinating to watch under a microscope.
And then, of course, there’s the one everyone pictures—mushroom-forming fungi. The phallic bit you know as a mushroom is, again, there to spread spores. Some are edible, some are super-duper-deadly, and some are just a bit weird.
But they’re actually only a really small slice of the fungal kingdom. It’s kind of funny that that’s what people picture. But I guess that makes sense.
Spores are these tiny reproductive cells that float through the air or water. When they land somewhere suitable—dark, damp, with something delicious to dissolve and slurp up—they grow.
A single mushroom can release billions and billions of spores. Most don’t land anywhere useful, but some will, and they become the next generation.
As for sex—well, some fungi reproduce asexually by just copying themselves. That’s basically cloning, if you will. Others reproduce sexually, combining genes from two individuals. Some species do both.
But sexual reproduction in fungi gets a little more complicated than you might think. They don’t have male and female the way we think about it. Many species have dozens, hundreds, or even thousands of mating types.
They’re not sexes. They’re not genders. They’re molecular markers within each individual that help them decide who should mix for the greater good.
The greater good. (Every time I say that, I think of Hot Fuzz.)
This obviously sounds unusual to us because we’ve categorised things very simply—but that’s science for you.
And it’s actually a very good moment to say this: sex in nature is far more complex than the tidy boxes people have tried to force it into.
In humans, biological sex isn’t binary. Intersex people exist. Hormones vary. Chromosomes don’t always line up with expectations. There’s a reason that when you’re a biology student at university, you don’t test your own DNA—because you might find out your genetics don’t reflect what you think they should.
Sex assigned at birth is a guess—and sometimes, it’s not accurate.
Science has never said it’s simple. It’s people who keep pretending it is.
And this matters—because the same people trying to erase or deny the existence of trans people are blatantly ignoring what science actually says. Which, of course, is a trend in that particular group of people.
Anyway—I just had to say that.
Fungi have survived and thrived for over a billion years with a system that defies categorisation of any kind. So maybe we could take a hint.
Hopefully, you’ll agree that this has been fascinating. More importantly, fungi are really useful. They’ve been quietly running things in the background of existence for as long as there has been life. Sometimes helping, sometimes harming, sometimes both simultaneously.
But beyond the whole “propping up life as we know it” thing, they also do some very cool things for us.
Obviously, penicillin is the most famous example. Penicillin comes from a group of moulds called Penicillium. The original notatum species was discovered in 1928—accidentally—and changed medicine forever. That original species isn’t the one we use now to make commercial quantities of penicillin, but that discovery kicked off the antibiotic era and saved, I suppose, hundreds of millions of lives.
Although, of course, if you listened to my episode on antimicrobial resistance a few weeks ago, you may know that the era of antibiotics may be drawing to a close.
Actually... cheese might be the most famous one.
I think most of us know that a lot of cheese involves some kind of fungi. The same genus—Penicillium—is what gives blue cheese its veins and its tang. It’s Penicillium roqueforti that gives it that classic flavour.
Honestly, I do not understand people’s willingness to eat a cheese that looks and smells like that—with veins of literal mould running through it. But clearly, I’m in the minority.
Then you’ve got Penicillium camemberti, which creates the white powdery rind on Brie and, obviously, Camembert.
Yeasts—like Saccharomyces cerevisiae—are the species responsible for both bread and beer. It eats sugar and produces carbon dioxide and alcohol. Deliciously useful. (Also in some situations, quite harmful—but we’ll come back to that.)
Lots of you will, of course, have heard of psilocybin—the active compound in some magic mushrooms. It’s now being studied seriously as a treatment for depression, PTSD, and more. And while the studies are still early, it’s proving pretty interesting.
Another drug that comes from fungi is cyclosporine. It’s a compound that suppresses your immune system, so it’s life-saving for people who’ve received an organ transplant.
And some of the statins—arguably the most widely prescribed drug on Earth—they also come from fungi.
In biotech, yeast cells are now used to produce human insulin, vaccines, experimental cancer drugs. It’s actually a cheap, fast, and fairly programmable way to make drugs—so they’ve become a pretty large part of synthetic biology.
They help us make new materials, too. Mycelium can be grown into sheets of leather, which is used in fashion, footwear, and packaging. Enzymes from fungi are in your laundry detergent—they help break down protein or blood stains on your clothes.
And if you’ve ever eaten soy sauce or miso—that’s fungi for you. Fermented flavour doesn’t happen without them.
But of course, not all fungal interactions are quite as fun—because athlete’s foot, ringworm, thrush... all fungi. All annoying. And if you have a suppressed immune system, they can be incredibly dangerous—because fungi love warm, damp places. Unfortunately, that’s most parts of us. Disgusting.
Ergot is a toxic fungus that infects rye and other grains. In the Middle Ages, it caused a very peculiar thing. It was called the dancing plague, where groups of people—sometimes hundreds—were reportedly dancing uncontrollably for days or even weeks in the streets until they died.
No one has any idea why. They couldn’t be stopped. The cause is still debated. But one theory is that it was ergot-contaminated bread, which triggered hallucinations and convulsions.
Thankfully, this isn’t something you can expect to come across too easily.
Fungal pathogens also devastate crops. Wheat rust, rice blast, Panama disease in bananas. They cause billions of dollars in damage. And that’s getting worse with climate change.
If you’ve seen Interstellar, the blight that wiped out all plant life on Earth and led to, I guess, an extinction-level event—that was most likely a fungus.
The Great Potato Famine—where Britain stole all of Ireland’s food and left hundreds of thousands of people to die of starvation—that was a fungus.
Then there’s something closer to home: Candida auris. It’s a drug-resistant fungal infection—which is never a good combination of words—and it’s causing serious problems in hospitals around the globe. It survives on surfaces for a very long time, resists multiple antifungal drugs, and kills vulnerable patients.
Saccharomyces cerevisiae—the same yeast I mentioned earlier that makes bread and beer possible—can also, in rare cases, cause fatal infections in immunocompromised people.
So to say that we’ve taken advantage of this kingdom of life in a multitude of ways really is an understatement. They’re infinitely more helpful than harmful.
And yet... I don’t think people have a good reaction when I say the word “fungi.” They think of mushrooms, or they think of fungal infections. And really, I think that’s unfair. They’re so underappreciated.
But beyond all those uses, there’s one thing that stands out the most about fungi—and that is, of course, their ability to help us unfuck the planet.
Because we’ve caused a shitload of problems. And as politicians just stand by and watch and nod insipidly, we head closer and closer to a boiled planet and a total crash in biodiversity.
Thankfully, there are many incredible scientists and entrepreneurs exploring fungi to solve these problems.
You may have heard of the term mycoremediation. “Myco” refers to anything related to fungi. Mycoremediation is the use of fungi to break down or absorb stuff in the environment that shouldn’t be there—like oil, pesticides, heavy metals. Even explosives.
Certain species can digest these pollutants and transform them into less harmful compounds—breaking them down and getting rid of them.
Then there’s mycofiltration. This uses mats of mycelium as filters. Water is trickled through the mycelium and—when they use these—the water comes out free of bacteria, free of nitrates (which is particularly of interest to us in Aotearoa), even free of microplastics.
And that is very interesting.
We’re in the very early stages of exploring how fungal networks could be used in carbon storage. Those mycorrhizal relationships—that symbiotic connection between fungi and plants—could be used to channel carbon into soils and keep it there.
Carbon capture technology has so far been an absolute disappointment—to no one’s surprise. But this version could be quite interesting, because fungal biomass decomposes very slowly. So hopefully, it’ll lock some of that carbon in place for decades—as opposed to trying to pump it into limestone, which... I don’t even know who did the maths on that.
Anyway—something people get very excited about is that there’s a type of fungi (in fact, a group of fungi) that can digest different types of plastics.
And one of these is polyurethane, which is one of the harder plastics for us to break down.
In lab studies, species like Pestalotiopsis microspora have been shown to digest polyurethane—even in low-oxygen environments like, of course, what exists in landfills. But this is still early-stage research. We’re not at the point where mushrooms are replacing landfills.
But it’s definitely interesting.
Fungi are also being used to rebuild degraded soils—which is super important, because not nearly enough people are worried about the fact that we lose an estimated 75 gigatonnes (that’s 75 billion tonnes) of topsoil every single year due to intensive farming, deforestation, and erosion.
Researchers and farmers have been adding fungal spores or mycelium mats to help restore microbial communities in the soil, which helps retain water and brings dead dirt back to life.
Because another problem in Interstellar, if you’ve seen it—and I honestly think it’s one of the most depressing movies out there—is that they had constant dust storms, because there was no plant life keeping the soil intact.
So—can fungi fix the planet?
Well, no. Of course not by themselves. As with everything, we need multiple solutions. They’re not going to stop climate change. They’re not going to reverse deforestation. Or vote out moronic governments who think the economy is the only thing that matters.
I’m not looking at anybody in particular... but I don’t know, the entire government right now?
But fungi are definitely a part of the solution. They have some super interesting properties that we’re really only just beginning to understand.
So hopefully, I’ve convinced you to join the Fungi Hype-phae Squad—which is probably the worst joke I’ve made on this entire podcast so far.
But that’s it for this episode of Now That’s What I Call Green.
Go and read more about fungi. It’s not just mushrooms—they do so much for you that you just don’t appreciate.
If you’ve got questions, feedback, or requests for future episodes, please flick them through. I do read them—even the comments where you tell me I speak too fast. I know. I know I speak too fast. I have tried to fix it.
Thankfully, if you like listening to a super slow podcast, you can put it on 0.5 speed.
I watch every single video online at at least 1.5, if not two times speed—because god, some of you people out there speak too slowly.
My doctor says I have a Ferrari brain with bicycle brakes—so I feel like it’s not my fault.
Anyway—don’t forget, the Microgreens episode will be up later this week. Zombie fungus, bleeding mushrooms, creepy gross things that grow on the ground, slime moulds, sentient custard…
I’ll leave it there. But it’s exactly as weird as it sounds.
Ka kite, fungal nerds. Catch you next time.
And there you go—I hope you learned something, and realised that being green isn’t about everything in your pantry matching with those silly glass jars or living in a commune.
If that’s your jam—fabulous. But sustainability at its heart is just using what you need.
If you enjoyed this episode, please don’t keep it to yourself—and feel free to drop me a rating and hit the subscribe button.
Kia ora, and I’ll see you next week.
