41: How Plants Communicate Transcript

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Hallie: Hello and welcome to One to Grow On. A show where we dig into questions about agriculture and try to understand how food production impacts us and our world. My name is Hallie Casey and I studied and currently work in agriculture.

Chris: I’m Chris Casey, Hallie’s dad and I don’t know anything about agriculture. Each episode, we pick an area of agriculture or food production to discuss and this week we’re focusing on fungal networks.

[Background music].

Hallie: Let’s get into it. Dad, what do you know about fungal networks specifically related to plants?

Chris: I know that there’s something called the mycelial network.

Hallie: Okay.

Chris: I know about it because of Star Trek Discovery.

Hallie: What?

Chris: Part of the premise of Star Trek Discovery is there’s some sort of mycelial network in space that a giant tardigrade can float around on.

Hallie: That doesn’t make any sense.

Chris: [Laughs]. I agree.

Hallie: If the tardigrade is giant, how is it floating around on the mycelia, which are tiny?

Chris: It was a little hand wavy even by Star Trek standards. It helped the enterprise go really far really fast. Faster than their normal work drive could take them. Oops! Editing Chris here. If you’re thinking, hey, Chris. Star Trek Discovery is about the discovery and not the enterprise. You’d be right. Hey, listener, editing Chris here. If you’re thinking Star Trek Discovery is about the discovery and not the enterprise, you’d be right.

Hallie: Because they rode the fungus.

Chris: Yeah, they rode the mycelial network.

Hallie: Mycelia is basically fungus.

Chris: Okay. But at some point their chief engineer takes over of the person that sort of flies them through the mycelial network because they don’t want to be cruel to the tardigrade.

Hallie: This doesn’t make any sense at all. [Laughs].

Chris: Star Trek, man. It’s about philosophy.

Hallie: Okay. Do you know what fungi is compared to mushrooms? Let’s start there.

Chris: So far as I know and of course I grew up with the five plant kingdoms and from what I remember from my education is fungus is one of the kingdoms and mushrooms are in that fungal kingdom along with athlete’s foot.

Hallie: Wait, you said five plant kingdoms.

Chris: Well, sorry. You’re right. I guess the five light kingdoms of life.

Hallie: Yeah, right. Yes.

Chris: Animals, plants, and then fungus there is another one that aren’t quite the same as plants.

Hallie: Separate from plants.

Chris: Right. Because they don’t have chlorophyll I guess, but more for them.

Hallie: Yeah, I have heard people say, they thought fungus was plants. Fungus is not plants. It is separate from plants.

The mushrooms are the fruiting bodies of the fungi and they’re just the very, very tip of the iceberg. The mycelia are actually the body of the fungus. They make up the majority of the fungus and then the hyphae are basically branching filaments that make up the mycelium, the total body of a fungus.

Chris: Wait, are they a berry?

Hallie: No.

Chris: [Laughs].

Hallie: Oh my God. Absolutely not.

Chris: All right. They’re not a berry. The mushroom part is like you said, the fruiting body.

Hallie: Yeah, pretty much.

Chris: When you say fruiting body, you mean that’s what produces the seed.

Hallie: It’s what produces the reproductive parts.

Chris: Yes, I was going to say, thank you for interrupting me.

Hallie: [Laughs].

Chris: Then on a mushroom the seed is I guess spores or at least that’s what I know of, but maybe they’re not all spores.

Hallie: I mean, we’re using the word seed here very liberally. I don’t know if we want to apply seed to the animal kingdom if we can extrapolate that way.

Chris: It’s not that kind of podcast.

Hallie: I wouldn’t say seed. Yeah, the fruiting body, meaning that that is what creates new mushrooms.

Chris: Got it. Okay.

Hallie: Then the mycelia is like the body of it. If we’re thinking about it in analogous to a plant, the mushroom would be like an apple and the mycelia would be all the rest of the tree.

Chris: Oh, okay. It’s not just the trunk or just the roots. It’s the whole thing.

Hallie: Then the hyphae is a branch.

Chris: I don’t think I’ve ever seen any part of a mushroom that wasn’t just the mushroom.

Hallie: The mushroom is the mushroom, right? The part of a fungi or fungus.

Chris: When I buy a mushroom at the grocery store or I see a mushroom growing on a log in the forest, there’s just this mushroom popping up and I don’t know what the mycelia part is.

Hallie: Right. I wanted to start talking about these different definitions because I want to get you away from that idea of a mushroom. Have you seen other fungus?

Chris: Oh, yeah. Because I used to work in a bakery and sometimes we’d have to throw the bread out or sometimes we keep food too long and that’s mold.

Hallie: Yeah, exactly. Boom answered. The mycelia there is the fuzzy bits. In the soil, they’re really, really small. Typically, they are microscopic, but they’re very important. We are specifically going to be talking about mycorrhiza fungi. That word, we can break it up into two parts. The word myco, meaning fungus in Greek and the word rhiza, meaning root in Greek.

Chris: Okay. Just to be clear, when I walk along the path in the forest and I see the mushrooms, there are fuzzy bits somewhere.

Hallie: Under the ground in the soil.

Chris: There are fuzzy bits.

Hallie: There is a network of branching hyphae filaments that make up the mycelium.

Chris: Wait, is that where the enterprise flies around?

Hallie: Yes, fine.

[Laughter].

Chris: I know you wanted to get away from mushrooms, but on a mushroom there’s the cap and the stock.

Hallie: Sometimes.

Chris: Is all that part of the fruiting body or is some of that part of the mycelia?

Hallie: Yeah.

Chris: All that’s part of the fruiting body and the mycelia is the fuzzy bits underground and there is a network of them.

Hallie: We said fuzzy bits because we were trying to envision fungus. When you really see an image of an underground, like mycelium, it looks like a tree. It’s massive.

It’s really interconnected. If you could imagine grassroots, like really, really fine hyphae that are connected and huge. It’s going to be super huge. It’s not like a little fuzzy spot. It’s a huge network of these branching hyphae that connect.

Chris: Like a rhizome?

Hallie: Yeah, right. But a fungus though. It’s like a fungi. Anyways, we got the image now. There are many different kinds of fungi. We are going to specifically be talking about mycorrhiza fungi.

Chris: Mycorrhiza fungi.

Hallie: Yeah, do you remember the Greek I said earlier? Myco meaning.

Chris: Fungus and rhiza meaning root.

Hallie: Exactly.

Chris: I remember because I’m looking at the show notes.

Hallie: [Laughs]. This is all we’re going to be talking about. Basically, plants need nutrients from the soil, right? But they don’t spread out very well. It takes them a lot of energy to spread out.

Most plant roots are built with carbohydrates and plants make carbohydrates using photosynthesis, so it’s a lot of work to photosynthesize. You know what does spread out really well is mycelium.

Chris: Why is that?

Hallie: Because they’re real small and it’s easy for them to get very many places and it’s just what they’re specialized to do. It’s what they do. Plants trade carbohydrates with fungi in the soil for basically nutrients. They get the nutrients from the fungi and the fungi gets some carbohydrates to go and build some more little hyphae somewhere else or to go build a mushroom. Then I found an article from the journal nature that said that 85% of vascular plants are in some kind of mycorrhiza relationship.

Chris: When the fuzzy bits spread out, they’re not just transporting nutrients to each other or to their fruiting bodies or whatever. Plants somehow use them to transport nutrients.

Hallie: Yeah, they’re basically in relationship with the plants in the ecosystem, which makes sense when we think about it as an ecosystem, which it is, but yeah, they’re basically like buying and selling nutrients and carbohydrates back and forth between these plants and the fungus.

Chris: But whenever I hear someone talk about their plant getting a fungus, it’s a bad thing.

Hallie: Well, yeah.

You can have issues with houseplants if a plant gets anaerobic, but those fungi in the soil are really, really crucial to a plant being able to get enough nutrients. Like everything else pretty much in the soil, you can have beneficial fungi and you can have detrimental fungi or pest fungi. Most of it is beneficial fungi. That mycorrhiza network is so key for plants.

Chris: Got it. Okay, cool. But I think we need to establish something pretty quick right now. Is it fungi or is it fungi?

Hallie: [Laughs]. I switched between the two, which is probably not correct. I think technically it’s fungi, but I always grew up saying fungi, so let’s stick with fungi for the rest of the episode because I’m pretty sure that’s the scientifically correct way to say it.

Chris: It’s fungi like the peanut butter.

Hallie: Fungi peanut butter? What is fungi peanut butter?

Chris: Fungi like the peanut butter, not fungi like graphics.

Hallie: Oh my God.

[Laughter].

Hallie: Man, I can’t even say that sentence. A gif jif joke for those of you at home.

Within these mycorrhiza fungi that we’re discussing today, there are two main types. There are ectomycorrhiza fungi and arbuscular mycorrhiza fungi. An ectomycorrhiza fungi, basically these two types are describing how the fungi gets in relationship with a plant. An ectomycorrhiza fungi, do you know the prefix ecto?

Chris: Yeah, that’s what ghosts create as ectoplasm.

Hallie: No, oh my God. I mean, yes, but like in the science, like actual, what does it actually mean in Latin?

Chris: Ecto, does it mean outer?

Hallie: Exactly. Right.

Chris: Okay.

Hallie: Ectomycorrhiza fungi, basically, if you think about plant root cells, they’re kind of built like a brick wall. They’re like these little boxes that are stacked next to each other and an ectomycorrhiza fungi will penetrate the root, but doesn’t penetrate the actual cells. It creates this sheath around those little brick cells, which can be very helpful in protecting the roots from nematodes or something like that that might want to come and eat it, but it basically comes out and creates a little wall around that little cell along the root. It’s ecto meaning outside of the cell. This is often associated with forests.

A lot of conifers have these ectomycorrhiza fungi relationships. They’re great. They’re terrific. The other type is arbuscular mycorrhiza fungi. I tried to figure out what the word arbuscular means. It is based on the word tree, right? Arbuscular basically these guys squeeze in the actual root cells in the plant cells. They get in the walls and they live in the cells and the little arbuscular, which are the bits of the fungi that are inside the actual plant cell spread out and look like tree branches, which is where we get that arbor connection because it kind of looks like a tree branch inside of the actual cell. This is really typical in things like grasses, not always. These connect to all kinds of different things.

Chris: That sounds amazing.

Hallie: Yeah, they’re both great. They’re both super cool.

Chris: But they both do essentially the same thing. They have some sort of relationship with the plant where they do like a nutrient exchange.

Hallie: Right. That’s what this mycorrhiza fungi do. This is just basically a different way of establishing that relationship with the plant.

Chris: Got it.

Hallie: Now we’re going to get into the crazy part. We’re on board for a plant knows a mushroom and they like trade stuff back and forth, but here where it gets intense.

Trees are not in kind of the traditional way that we think about them, an individual organism.

Chris: Because they’re socialists?

Hallie: Because these fungal relationships form something that scientists have been calling the Wood Wide Web.

Chris: [Laughs]. Oh, mad respect.

Hallie: I think it’s good.

Chris: But wait, I don’t think I understand what it is you’re saying about why they’re not individuals. Trees are not individuals because they talk to each other or because they have the Wood Wide Web too. That goes between the tree roots so that the trees can talk to each other over the fungal network.

Hallie: Yeah, it’s basically that second one. This Wood Wide Web is a way of reimagining what we think of as a forest ecosystem. A lot of this work was pioneered by an amazing scientist, Suzanne Simard from the University of British Columbia and here’s like how she figured it out. What she did was she put a traceable form of carbon in a tree in a forest. Then she took samples from a neighboring tree at a later date and found carbon in the other tree that she did not put it in.

Chris: Dude.

Hallie: A tree had taken a carbon and put it down into the Wood Wide Web into this giant fungal mycelium and it had gone into a different tree.

Chris: Is she sure that the tree just didn’t reach over and said here have some of my carbon?

Hallie: We’re pretty sure that’s not what happened [laughs].

Chris: Okay. I mean, maybe a leaf fell and the leaf decomposed and then the other tree absorbed. I’m sorry. None of that’s correct. This is insane. That’s wild.

Hallie: Yeah, I did a lot of research on this and a lot of the analogies I found were actually specifically talking about the internet and how it’s kind of a series of tubes that connects servers.

Chris: Oh, boy.

Hallie: These trees can be thought of as servers and sometimes you have smaller servers or bigger servers. A bigger server would be a really big older tree. What’s often called like a mother tree when thinking about this type of framing of the ecosystem. What scientists have seen is that you have these source plants and then you have these sinking plants. Plants make carbohydrates, right? Using oxygen and carbon dioxide and using photon energy they create a carbohydrate. However, if you are on forest, you will have a big tree that gets much sun and many photons and you’ll have a small little tiny baby tree that will be under the big tree.

When you’re under the big tree, you get very few photons. You see what I’m saying?

Chris: Is this nature’s version of trickle-down economics?

Hallie: No, oh my God.

Chris: [Laughs].

Hallie: It’s like nature’s version of motherhood. That’s why it’s called Mother Theresa.

Chris: Oh, okay.

Hallie: This big tree will pass carbohydrates across the Wood Wide Web to these little small trees so that they can continue to survive. They have seen examples of trees that are getting very, very few photons that are really not photosynthesizing a lot, but are able to continue to survive because they’re basically getting carbohydrates from the rest of their community.

Chris: Wait, can I use this in my backyard to grow plants that otherwise wouldn’t grow in the shade?

Hallie: Yeah, you know what you need in order to establish a good Wood Wide Web in your backyard.

Chris: What?

Hallie: Compost. You should compost, dad.

[Laughter].

Chris: I mean, that I have to go through the action of composting.

Hallie: You can also buy compost, but if you’re buying compost in order to establish the mycelial network, you do have to buy an active compost that’s not dead because you need living things in it like fungi.

Chris: Got it.

Hallie: They send carbohydrates. They can also send nutrients around. They can also send water around and it has also been found that they can also send stress chemicals and like warning signals around on these internet of trees.

Chris: I’m just thinking of all the HTTP codes on the web. They can send two hundreds and five hundreds and maybe even a 404.

Hallie: Sure, dad?

Chris: Yeah.

[Laughter].

Hallie: Absolutely.

Chris: Site not found. I don’t know.

Hallie: What is the 500 code? I don’t know that one.

Chris: Internal server error.

Hallie: Okay. Yeah, I don’t really know what that means, but yeah, absolutely if that helps, sure.

Chris: That’s just, wow. Stress chemicals. I’m like, look out there’s a woodpecker or something.

Hallie: Yeah, exactly that. Look out, something is coming eating our leaves perhaps make more cellulose if you can. Something’s coming and then they will.

Chris: Well, that’s cool and herbicides too this is?

Hallie: Yeah, you’re reading a little bit ahead.

Chris: True.

Hallie: They can also transport things like herbicides, which we don’t really want transported, but that hasn’t been as studied, partly because if you’re using something like an herbicide, then that’s often diminishing the soil ecosystem, right? If we’re growing in a more conventional system, then you usually have a less robust soil ecosystem. Not that that has to be the case that you can’t use herbicides in a system that has a robust soil ecosystem. But as we’ve talked about on the show before, we can always use more science about regenerative, agricultural practices and soil science and soil health.

Chris: That is good.

Hallie: One of the other interesting things that they found about these “mother trees” is that when they are dying, they take the carbon that has been stored a lot, not all of it obviously, but they take some of the carbon, they have stored and they release that and as well as other nutrients back into the network, so they’re basically passing resources onto the next generation and it kind of speeds up their death. One of the things that a lot of forestry scientists have been talking about for the last, however long, like since the nineties, when this research was being done is considering that when we cut down these larger trees to make plywood or whatever, we’re basically taking those resources out, so it can be harder for the next generation of trees to actually grow up to maturity because they don’t have that kick start as these mother trees who are aging out and passing those resources on.

Chris: Man, that’s wow. Okay. Is this more like an Ethernet or like a token ring thing?

Hallie: I don’t know. I think that’s the point where we should perhaps get into the break because you were talking way beyond what I know of the internet.

Chris: [Laughs]. Into the break.

[Background music].

Chris: You really should learn more about computers and the internet and the way it all works I think.

Hallie: You know what? I do know more about our starfruit patrons.

Chris: What? Vikram, Lindsay, Patrick, Mama Casey and Shianne.

Hallie: Our starfruit patrons and all of our patrons have made our local food series possible. They have made it possible for us to get transcripts. They have made so many things possible for us to grow the show, things that have happened and things that are coming up that we’re planning. If you’re interested in supporting the show, we have perks at all kinds of different levels from $1 all the way up to $25 is the highest tier. We have pretty fun perks. If you’re interested, you can come join us over there at patreon.com/onetogrowonpod.

Chris: That’s patreon.com/onetogrowonpod. We would love to see you there. Back to the episode.

[Background music].

Hallie: Dad, do you have a nature fact for us?

Chris: I do.

Hallie: Great.

Chris: All right. Earlier we established that in Star Trek Discovery they used the mycelial network to fly around.

Hallie: Yeah.

Chris: Okay. The engineer that was able to fly them around the mycelial network was played by Anthony Rapp.

Hallie: No way.

Chris: Oh, yeah way.

Hallie: You’re kidding. Broadway King Anthony Rapp was on the Star Trek.

Chris: As you know, Anthony Rapp was big in Rent.

Hallie: I mean, he was the lead in Rent.

Chris: Yes, the reason he was able to do so well in Rent is because he was a fun guy.

Hallie: What?

Chris: [Laughs]. He was a fun guy.

Hallie: That doesn’t even make any sense.

Chris: [Laughs].

Hallie: Oh, my God.

Chris: Also, there are mushrooms that go in the dark and they look really cool and you should look them up.

Hallie: I can’t even believe you could even come up with a Rent appropriate pun.

Chris: [Laughs].

Hallie: The amount of Rent that you had to listen to when I was in high school and you couldn’t even come up with a Rent specific pun.

Chris: Oh, man. I did try to see if they talked about there being mold in the building, but there was no reference to it.

Hallie: No.

Chris: They were just jerks who didn’t want to pay rent.

Hallie: No, that’s not the takeaway at all from Rent.

Chris: Not the takeaway. It’s just who they were as characters.

Hallie: No, we don’t have the time to talk about how wrong you are.

Chris: [Laughs]. Thank God.

Hallie: Moving on. Back to fungus. There has been some cool research that’s shown that nutrient transfer from old growth. Douglas firs happens more with plants that are related to them like other conifers versus plants that are more distantly related to them, like broad leaf plants.

We don’t know how they know. We don’t know why that happens. It’s not like they’re talking to them. They’re talking to the fungi who is then talking to the plants. How do they tell the fungi, “Hey, take this to that tree over there, but not to that tree because that tree and me are not bros?” How do they know?

Chris: I don’t know. But it sounds like they got a little tribal thing going on.

Hallie: I want to know how they know so badly. It’s so weird.

Chris: Maybe they can see each other. I don’t know. That is pretty wild though.

Hallie: It’s wild.

Chris: Maybe it’s like some sort of gene expression over the network.

Hallie: I really don’t know. Yeah, there is so much we don’t know about this whole network. There’s so many more things that we will be learning in the next like 50 years and I’m sure in 50 years we are going to know so much more and it’s going to blow my freaking mind.

Chris: Maybe they just ask, “Is your name Douglas?” They say, “Yes.”

Hallie: That’s probably what the fungi do actually. Now that I think about it, that’s probably exactly what they do.

Chris: All right. Cool. Let’s go for that.

[Laughter].

Hallie: I want to talk a little bit more about the context of this in agriculture. We talked a lot about forestry in an oblique way, so obviously this is very relevant for our timber industries. We haven’t done an episode on timber yet, but we’re planning on doing it eventually. It’s like on my list of things I really want to talk about. But yeah, this is super connected, but mycorrhiza fungi don’t just exist in trees. We know about them mostly in trees because it’s pretty easy to put a weird carbon in a tree and then come back a while later and look at another tree, but if you have annual plants, you might not have the lifespan to really be able to measure what’s being passed back and forth, right? There is still really cool science being done. But like we do know that these mycorrhiza fungi are important to annual crops like tomatoes, wheat. Most of the things that we eat. We do know that they are important. We don’t just have as much science because there’s always more science we can be doing.

Chris: That is true.

Hallie: There is evidence that plants that are plugged into the network from a young age are generally healthier. Why? We don’t really know. It could be because they have more available nutrients when they’re young and so they’re able to grow to be more robust. It could be because they have more access to stress hormones, so they get less damaged. There could be other reasons that we don’t know of.

Chris: They’ve got mycelia privilege.

Hallie: Exactly. What does that mean? Who knows? We don’t know yet, but hopefully we will know soon. There can issues in agriculture related to the mycelia network. Overuse of fertilizer can damage mycorrhiza networks basically because the plants don’t need the fungi to provide nutrients, so they’re not giving the carbohydrates back to the fungal network.

Chris: Oh, that makes sense.

Hallie: Yeah, that’s specific to fertilizers, but we do know that large scale industrial agriculture does damage soil health. We can talk specifically about mycorrhiza fungi, but what we do definitely know and what is really clear is that the fungal network, this mycelium under the ground is related to nematodes and is related to protozoa and is related to plants and is related to bacteria, all of which are growing in the soil together. If one of those pieces is missing, like if you don’t have as much plant diversity, then that can damage all of the other pieces that create a healthy biological soil. If you have a healthy biological soil, then you also have a healthy physical soil and chemical soil. All of these different aspects of the soil and how it functions can function much better. You see what I’m saying?

Chris: It’s sort of like when everything lives together in harmony, it all works out better.

Hallie: I mean, yeah, sure. If we extrapolate very far back, that is what I am saying.

Chris: It’s a metaphor for life.

Hallie: Yeah, it’s a metaphor for life. We need balance including mycelium. It’s very important.

Chris: Cool. In conclusion, the trees talk to the mushrooms and the mushrooms relay the messages to other trees, or sometimes even other plants or at least trees of other species or whatever, but not usually. They all live together with their friends, the bacteria and the nematodes and the other things and good healthy soil, which is important. It’s just cool and amazing and important for a healthy ecosystem.

Hallie: That’s the stuff of it.

Chris: That’s the stuff of it, man. Well, thanks. Hallie, you know what? I had fun guy.

Hallie: Oh, my God. Well, I had mushroom.

Chris: You had mushroom for what? That makes no sense.

Hallie: Yeah, well, yours isn’t great either.

Chris: That’s true. Okay.

[Background music].

Chris: Thanks for listening to this episode of One to Grow On.

Hallie: This show is made by me, Hallie Casey and Chris Casey. Our music is Something Elated by Broke for Free.

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Chris: Be sure to see what’s sprouting in two weeks.

Hallie: But until then, keep on growing.

[Background music].