May 20, 2025
Tree, Myself and I: All about our leafy green friends
Download Lesson PlanSubscribe
Apple Podcasts
Spotify
Amazon Music
iHeart
TuneIn
YouTube
RSSTrees are the strong, silent type but that doesn’t mean they can’t communicate. In this episode we’ll explore how trees send each other messages above ground and below. Plus we’ll learn how a seed goes from a tiny sapling to a towering plant. We find out some fruit facts and hear an all new Mystery Sound.
This episode was originally published on Jul 16, 2019.
Audio Transcript
Download transcript (PDF)
JULIUS: You're listening to Brains On, where we're serious about being curious.
ANNOUNCER 1: Brains On is supported in part by a grant from the National Science Foundation.
MARC SANCHEZ: OK, America, Roshambo. Whoever wins this gets to try out the cheese ray first.
MANEKA: Sweet beams of gouda, here I come.
MARC SANCHEZ: Ready?
MANEKA: Oh, yeah.
BOTH: Rock, paper scissors.
SAPENA: Tree.
MANEKA: Uh, Marc, did you say tree?
MARC SANCHEZ: No. That wasn't you? Whatever. Let's try this again.
MANEKA: Yeah, one more time.
BOTH: Rock, paper, scissors.
SAPENA: Tree.
MARC SANCHEZ: OK, I definitely heard tree.
SAPENA: Trees beat rocks because trees can eat sunshine and rocks can't.
MANEKA: I think the voice is coming from the window.
SAPENA: They beat paper because paper is just old trees, and old never beats young.
MARC SANCHEZ: Oh, behind the blinds, on the window sill. It's a sapling in a pot.
SAPENA: And trees beat scissors because when we are big and mighty, nothing can get through us. Trees win.
MANEKA: I don't think that's how the game works exactly.
SAPENA: Also, a talking sapling? Oh, please. You guys have talking bugs on your show all the time. Are you really surprised?
MARC SANCHEZ: Good point, sapling. Good point. Plus, Sanden has been experimenting with giving voices to inanimate objects. He's been paranoid that the staplers are plotting against him, and he wanted to get intel from the water cooler.
[JAZZ NOTES]
MANEKA: So what's going on, tiny tree.
SAPENA: The name is Sapena, and I'm just photosynthesizing and pondering the big questions. Like, if I was all alone in a forest and I fell down, would I make a sound? JK. LOL! Of course, I'd make a sound. I'd sound like this, ow, I fell over. Ouch, that hurts. Someone call a tree doctor.
MARC SANCHEZ: Hey oh! [CHUCKLES] You're pretty funny. You know, Molly is literally about to do an episode about trees right this very minute. We should totally have you on.
SAPENA: Me? What could I possibly talk about? Psych! I can talk about anything. I have so much to say. Want to hear my thoughts on ponies versus puppies, or the best kind of not? I'm a big fan of the figure 8, but a timber hitch--
MANEKA: OK, come here, tiny tree. Let's get you to the studio.
MARC SANCHEZ: OK, you guys go ahead. Let me just put this cheese right away. I'll get the-- whoa!
SAPENA: Whoa! You just turned the copier into cheddar.
MARC SANCHEZ: Oops, I guess my finger slipped. But, Menaka, if you hurry back, you can help me eat this.
[THEME MUSIC]
MOLLY BLOOM: You're listening to Brains On from APM Studios. I'm Molly Bloom. Brains On is public media. And public media is threatened like never before. To keep doing what we do, we need your help. We need you. Your donation can make sure Brains On sticks around through all this uncertainty. But we need you to give now. Like, right now. Please go to brainson.org/donate. Any amount is helpful. $10, $5. Maybe you like prime numbers and want to go for $83.
Just head to brainson.org/donate. That's brainson.org/donate. Thank you, thank you, thank you. Today I am very excited to welcome my co-host Julius from London, England. Hello, Julius.
JULIUS: Hello! We're also joined by Sapena. She's a tree sapling. That's what you call a small, young tree.
SAPENA: Hi. I'm Sapena, and I'm a blackjack oak.
MOLLY BLOOM: Today we're talking trees. And Julius, you wrote in to us a long time asking about trees. I'm just wondering, do you still think about trees?
JULIUS: Yeah, I do, I guess. I always wondered how they communicate and stuff like that.
MOLLY BLOOM: That's very interesting. Do you have a favorite kind of tree?
JULIUS: Um, I would have to say maple because of maple syrup.
MOLLY BLOOM: It's very delicious. When you think of a tree, what is the first part of the tree that you think of?
JULIUS: The first part of the tree I think of is the branches, because, you know, calculating the best way to get up it.
MOLLY BLOOM: Definitely. [CHUCKLES] Finding your climbing route.
JULIUS: Yeah, I think one of my favorite outdoor activities is probably tree climbing, so--
MOLLY BLOOM: Oh. Do you have any tree-climbing tips?
JULIUS: Upper body strength is really important.
MOLLY BLOOM: And do some training first.
JULIUS: Pulling yourself-- yeah, you have to train.
MOLLY BLOOM: What about you, Sapena? Do you think about trees a lot too?
SAPENA: Oh, yeah, I think about trees all the time. We're just so amazing.
MOLLY BLOOM: That makes sense. And you are in good company. Our listeners like pondering trees too.
MALCOLM: Hi. My name is Malcolm. My question is, what happens inside of a tree while it is growing?
OLER: Hello. My name is Oler, and my question is, how do trees grow.
SARAH: Hi. My name is Sarah, and my question is, how do trees grow?
CLAIRE: My name is Claire. How did little tiny seeds become big trees?
JULIAN: Hello. My name is Julian. I'm eight years old. My question is, how do trees grow? And while they're growing, how do the branches form? Thank you, and keep up the good work.
MOLLY BLOOM: Thanks, Julian. So, Sapena, since you're here, maybe you can help us answer some of these questions.
SAPENA: Totally happy to help. I'll take you through all the levels I've gone through to get here.
JULIUS: Levels?
SAPENA: Yeah. You can think of growing into a tree kind of like playing a video game. You complete level 1, and it's on to the next. Lucky for you, I've been recording my game on twig.tv. Check it out.
[BEEPING]
ROBOTIC VOICE 1: Level 1, seeds can't run.
[ARCADE MUSIC]
SAPENA: OK, so in this level, I'm a seed. I can't move. My foes--
ROBOTIC VOICE 1: The forces of chaos.
SAPENA: I have to avoid getting eaten or destroyed.
[BIRD SQUAWKS]
Oh, no, a bird! Phew, it flew away.
[BIRD SQUAWKS]
Oh, this level is almost all luck. But thankfully, I find a good spot to grow. I make it to--
[VICTORIOUS NOTES]
ROBOTIC VOICE 1: Level 2, start to thrive.
[ARCADE MUSIC]
SAPENA: As a seed, I have all the food and instructions I need to start life as a tree. This level is all about letting water into my seed and chomping on the starch stores in my seed so I can grow and get to--
ROBOTIC VOICE 1: Level 3, sprouting root.
[EXCITING ARCADE MUSIC]
SAPENA: So now I'm still chomping on starch from my seed because I can't make my own food yet. But I'm running out of starch. I have to break out of this shell. So I grow my first root.
[RUMBLING]
I am Root. And I grow a little shoot, my first little stem from the top of my seed too. I follow gravity to point my root down and follow sunlight to grow my shoot up. Once my shoot grows through the dirt into the air--
[VICTORIOUS NOTES]
ROBOTIC VOICE 1: Level four, first leaf.
[EXCITING ARCADE MUSIC]
SAPENA: This is a big one. I grow above ground and get my first leaves. So this level is when I start doing my own photosynthesis. That means I take in water, carbon dioxide, and sunlight, and make oxygen and sugar. I can make my own food from light. And thank goodness, seed starch is for plant noobs.
MOLLY BLOOM: Wow, thanks, Sapena, but we like seed starch.
JULIUS: Yeah. When people eat rice, they're eating seed starch. Flour is ground up seed starch too.
SAPENA: It seems a little weird to eat seed starch if you don't even grow roots or leaves. But anyways, those are all the levels I've beat so far.
ROBOTIC VOICE 1: Progress saved. Bark boss awaits.
SAPENA: I have some leaves now and a few different branches, and I think in the next stage, I do more growing. But I can't seem to beat the bark boss that unlocks my bark-growing powers.
JULIUS: Hmm, seems tricky.
MOLLY BLOOM: I think I know who can help. We have this tree museum on the 11th floor, actually. I bet we could figure out your next steps there.
SAPENA: For realsies? A tree museum? I mean, obviously, because trees are totally museum worthy, but, like, I could meet some other trees there?
MOLLY BLOOM: Yeah, all kinds of trees.
SAPENA: Oh, wow, wow. Yes, please. Let's go right now. Lead the way, and also, carry me because I have no legs.
MOLLY BLOOM: OK, Sapena, we'll go in a sec. But first, a little sonic sleuthing. It's the--
[WHOOSHING]
PRESENTER 2: (WHISPERING) Mystery sound.
MOLLY BLOOM: Are you ready, Julius?
JULIUS: Yeah.
MOLLY BLOOM: All right, here it is.
[CRUNCHING SOUNDS]
Any guesses?
JULIUS: Uh, If i had to guess, maybe somebody's eating something.
MOLLY BLOOM: Hmm, very, very good guess. Well, we'll be back with the answer and another chance for you to guess a little bit later in the show.
ROBOTIC VOICE 2: Brains brains brains on.
[FOOTSTEPS]
MOLLY BLOOM: OK, it should be right down this hall.
SAPENA: I see it, I see it, the Tree Hall of Fame. You guys, there it is.
[DOOR OPENS]
MOLLY BLOOM: Wow, this is actually much bigger than I was remembering.
JULIUS: Are we outside? Where is all that sky coming from?
HYPERION: Well, hello, down there.
MOLLY BLOOM: Uh, hi.
HYPERION: I am Hyperion, the tallest known tree in the world.
SAPENA: No way! I have your trading card. You're like a living high score. You are my hero.
HYPERION: Oh, (CHUCKLING) that's so nice to hear.
SAPENA: Yeah, you are a Sequoia sempervirens, or, you know, a Coast Redwood. You live in the Redwood National Park in California, and you're a whopping 380 tall.
HYPERION: You know your stuff, little one.
SAPENA: I am devoted to my stem education.
JULIUS: STEM? You mean Science, Technology, Engineering and Math?
SAPENA: What? No, dude. I mean stem, like studying trees every minute, because trees are the best. Oh, over there, is that--
GENERAL SHERMAN: General Sherman's my name. Largest living tree is my claim to fame. Pleased to meet you, fine friends.
MOLLY BLOOM: Wait, wasn't that other tree the largest.
GENERAL SHERMAN: [CHUCKLES] Silly human.
SAPENA: Yeah, silly human. Hyperion is the tallest known tree. General Sherman is the largest. That's measured by volume. It includes height and width.
GENERAL SHERMAN: That's right. I'm a giant sequoia living in Sequoia National Park, California. I'm certainly no slender sapling. If you're looking for lean lumber, you're barking up the wrong tree. [LAUGHS]
SAPENA: [LAUGHS] Tree jokes, it has tree jokes. Oh, mighty General Sherman, the tree, how can I grow big and tall like you and Hyperion?
GENERAL SHERMAN: Be patient, little sapling. It takes time, yes. But with luck, it will happen. [CHUCKLES] As you age, your bark will get harder and darker, but it won't be the bark that will make you thick and robust like us. [CHUCKLES] No. It's the stuff right under your bark called the cambium.
SAPENA: The cambium?
GENERAL SHERMAN: Yes, indeed. It's a woody plant tissue. And over the years, it will grow outward, making a tree wider and mightier. At the same time, your roots will grow deep into the ground, snaking their way through the soil to bring you water and nutrients and branches. You'll grow many more branches filled with sun-eating leaves. Those will feed you. I enjoy that quite a bit. Eventually, you'll start growing seeds of your own. Some may even end up in the soil where they'll grow into other trees.
SAPENA: Oh, wow. Oh, wow. I cannot wait.
GENERAL SHERMAN: [CHUCKLES] Well, treeing is not about speed. Indeed, I've been growing for over 600 years, and I've been at it for over 2,000.
MOLLY BLOOM: Wow, that's amazing.
JULIUS: Yeah, you guys are ancient.
METHUSELAH: Did someone say egg ship? I'd like to see an egg ship.
MOLLY BLOOM: Uh, what?
GENERAL SHERMAN: Ancient. He said ancient. Don't mind Methuselah there. Methuselah is the world's oldest known tree. A legend. It's a bristlecone pine that's been growing in the Eastern mountains of California for over 4,800 years.
METHUSELAH: Are the eggs riding the ship, or is it a ship made of eggs? [CHUCKLES, COUGHS] Either way, count me in.
GENERAL SHERMAN: Its hearing isn't great.
SAPENA: Wow, you guys have so much wisdom, so much bark. I'd love to learn more from you.
GENERAL SHERMAN: Then why don't you join us? We could talk tree stuff and, you know, our favorite types of knots from time to time.
SAPENA: What? I love knots too.
MOLLY BLOOM: You know, it seems like you're really happy here. Why don't you stay, Sapena? You know, lay down some roots. This is a perfect home for you.
SAPENA: Really? OK, I will. Thanks so much, Molly and Julius.
JULIUS: We should get back to the studio anyway. See you trees later.
MOLLY BLOOM: Bye.
SAPENA: Bye, Molly. Bye, Julius.
GENERAL SHERMAN: Farewell. Sad to see you leaf. [LAUGHS]
SAPENA: [LAUGHS]
HYPERION: [CHUCKLES] Come bark soon. We're rooting for you.
METHUSELAH: Maybe one of the eggs is a pirate.
ROBOTIC VOICE 2 Buh, buh, buh, buh, buh, buh, buh, buh, Brains On.
[EXCITING MUSIC]
MOLLY BLOOM: Right now, we're working on an episode all about astronauts, and we want to hear from you. What food do you think might be particularly tricky to eat while floating around in microgravity up in space? Record your answer and send it to us at brainson.org/contact.
JULIUS: And that's where you can also send us questions, drawings, mystery sounds, and high fives.
MOLLY BLOOM: That's how we received this excellent question.
ARTURO: Hi. My name is Arturo from Tucson, Arizona. And my question is, why does the moon change color sometimes?
MOLLY BLOOM: You can find an answer on our Moment of Um podcast, a short dose of facts and fun every weekday. Find it wherever you listen to Brains On. And keep listening.
PRESENTER 3: Brains On Universe is a family of podcasts for kids and their adults. Since you're a fan of Brains On, you'll love the other shows in our universe. Come on, let's explore.
[AIRCRAFT WHIRRING]
ROBOTIC VOICE 3: [PANTING] Its alien exercise hour! Hi yah! Hoo hah! While I stretch my snoodles and bounce on my trampolini, I'll listen to a new podcast. [LAUGHS]
[BUZZER]
I'm going to try Forever Ago, the best history podcast ever.
[BEEPING]
PRESENTER 3: To understand why anyone would think a TV show could change the world, we need to go way back--
[WHOOSHING]
--to America in the 1960s.
[ROCK AND ROLL MUSIC]
PRESENTER 4: Rock and roll was pretty new.
PRESENTER 3: Ford released the iconic Mustang muscle--
[BEEPING]
ROBOTIC VOICE 3: Zorb. Come back here, podcast. [BEEPING] Must listen to Forever Ago now!
[WHOOSHING]
PRESENTER 3: Listen to Forever Ago wherever you get your podcasts.
JULIUS: You're listening to Brains On from American Public Media. I'm Julius.
MOLLY BLOOM: And I'm Molly. Hey, Julius, I think we should get back to that mystery sound right away. Are you ready?
JULIUS: Yeah.
MOLLY BLOOM: OK, before we get back into it, before you said it was someone eating, and here's a clue. They're eating something that you might get from a tree. OK, here it is again.
[CRUNCHING SOUNDS]
Any new guesses?
JULIUS: Uh, I would guess an apple.
MOLLY BLOOM: You are 100% correct. That is the sound of someone eating an apple. Very good ears. Are you an apple eater yourself?
JULIUS: Uh, yes, it is one of my favorite fruits.
MOLLY BLOOM: What is your favorite way to eat an apple?
JULIUS: I always eat it from top to bottom, eating everything, really.
MOLLY BLOOM: Explain more about that. So, like, you start from, like, where the stem is?
JULIUS: So I put out the stem. I then eat it all the way from the top. I even eat the core. And then, you know, nothing left at the end.
MOLLY BLOOM: Do you eat the seeds too?
JULIUS: Yeah.
MOLLY BLOOM: Wow, you really like apples.
[MUSIC PLAYING]
And our listeners have some fruit questions as well.
LOUIS: My name is Louis from Adelaide, Australia. My question is, how does fruit grow on trees?
JUDE: Hi, my name is Jude from Charlottesville, Virginia. My question is, why does fruit grow on trees.
MOLLY BLOOM: So I went to the University of Minnesota Orchard where I met Jim Luby. He's a professor of horticultural science and also one of the scientists who brought us the honeycrisp apple, an apple, which, like the name describes, was bred to be very crispy and sweet.
JIM LUBY: This is the oldest honeycrisp tree in the world. It dates back to about the mid 1970s.
MOLLY BLOOM: So Jim knows his apple trees, and he showed me how these trees make fruit.
JIM LUBY: So if we want to go over to this tree here, what we can see here is a little shoot. And this shoot grew last year. And then at the end of it, it formed what we call a terminal bud.
MOLLY BLOOM: So picture a tiny little nub on the branch of an apple tree. It's called terminal because it's at the end of the shoot that comes off the branch.
JIM LUBY: And probably late last summer, it went from growing leaves on this little shoot to stopping growth at that terminal bud. And so those flowers start developing inside that little bud through the late summer and fall. Then the whole tree, of course, goes dormant, loses its leaves and goes dormant. And then the following spring, those flowers will continue to develop in the bud. The bud eventually breaks. We see those nice, white-pink flowers. Hopefully, a bee or other pollinator comes by and deposits some pollen from a different tree.
MOLLY BLOOM: Pollen is that yellow, powdery stuff you'll see in the center of flowers. All of the flowers on the apple tree have nectar and pollen to attract bees to them. But that pollen also has another purpose. It can accidentally take pollen from one tree's flower to a flower on a totally different tree. That will fertilize a cell in that flower, and it will start growing a seed. And around that seed, fruit cells will start growing.
JIM LUBY: The fruit will start enlarging. Also, during the summer, it's packing lots of starch into this fruit. And eventually, as the fruit ripens, that starch will be converted to sugar. And that's what you and I would recognize as the sweetness of an apple.
MOLLY BLOOM: But it's worth it, because animals who want to eat these apples will then help spread their seeds around by gobbling up apples and pooping out the seeds somewhere else. Then, from that humble beginning, a new tree will grow. The apple trees native to North America are tiny crab apples because they were eaten by smaller animals. And all those big apples that we think of as well, apples, those can trace their roots back to Kazakhstan, where they were eaten by bears.
JIM LUBY: And I've been actually over to Kazakhstan. And what you'll see is some-- you'll see brown bear dung, and it's full of apple seeds.
[MUSIC PLAYING]
MOLLY BLOOM: I don't know about you, but I find trees very calming to be around. My daughter hugs every tree she sees when she's walking down the street. I want to know, Julius, do you feel a connection to trees? I know you climb them. But have you ever hugged one, or how does being around a tree make you feel?
JULIUS: I know that they give me oxygen. They basically keep us alive. So for that, I'm grateful. So I suppose, you know, I'm happy they're around.
MOLLY BLOOM: I find it like-- I don't know. I just feel like I've. I slowed down a little bit when I'm near a tree.
JULIUS: Yeah.
MOLLY BLOOM: Trees do have a certain magic. They can't talk like we can.
JULIUS: Except Sapena and those other trees.
MOLLY BLOOM: Right. Well, most trees can't talk and they can't get around, but they're definitely alive. We wanted to know more about what they're up to, so we called David George Haskell.
JULIUS: He's a biologist at Sewanee, the University of the South, and he wrote a book called The Songs of Trees. Welcome, David.
DAVID GEORGE HASKELL: Thank you. It's a delight to be with you.
JULIUS: Is it true that trees use underground signals to communicate with each other?
DAVID GEORGE HASKELL: Absolutely. This is one of the revolutions in biology of the last few decades, is that we used to think trees were solitary individuals, each doing their own thing, deaf to the world. And now we know that they're engaged in this intimate conversation, both below ground and above ground with other trees, but also with other organisms, with the insects and then the bacteria and fungi in the soil as well. So they're very chatty organisms. They are indeed communicating, but of course, not using a language as a human language, but using their own tree method of communication, which is mostly through the medium of chemicals.
JULIUS: Cool. So can a tree tell when another tree needs help, like, when it's being attacked?
DAVID GEORGE HASKELL: Indeed, it can. Now whether the other tree is able to provide any help or not really depends on the situation. But if insects, for example, attack one tree in a forest, the other trees around it will learn of that attack and will defend themselves before any insects hit them. And they know this through a couple-- at least, a couple of different means. One is through airborne chemicals, little aromatic molecules that drift out of the injured tree's leaves and waft away into the air.
And the leaves around that injured tree then receive those chemicals. They smell them through their leaves because the leaves, of course, are open to the air. That's how they function. They draw in air through little breathing pores. And with that air comes these little alarm chemicals. The other method is below ground. It seems that chemicals are moving from one tree to another via pathway that involves the tree's roots, that are connected to fungi below ground, that are then connected to more tree roots, so that there's a whole hidden network of chemical conversation happening under the ground, as well as in the air.
JULIUS: Why do trees communicate? Because if they've got all these self-defense mechanisms, what is the need of actually saying if some insects are attacking you-- like, why aren't they solitary figures.
DAVID GEORGE HASKELL: So in this way, they're analogous to human communication. Why do we talk to one another. Partly, it's to learn things that are going to be helpful to us. And through experiments, monitoring the communication of trees and what they gain, people have found that trees that are-- and not just trees, other plants as well that are communicating one to another can protect themselves from drought. They can deter herbivores more effectively. They can get more carbon and nitrogen into their bodies. They can receive advance warning of what's happening in the forest.
JULIUS: So do you think that someday people will be-- can learn to understand tree communication? Like, is there a simple thing we can do to understand it?
DAVID GEORGE HASKELL: I think people have been doing this for thousands of years. Trees center in many of our important stories about meaning. Think about the tree of the knowledge of good and evil, or the tree under which the Buddha was enlightened. We understand in our culture that trees are symbols of meaning and understanding and wisdom. So we've been listening to them through culture and literature and poetry for many centuries. Now science is catching up and teaching us new things about how trees can connect one to another.
I would recommend, and this has been my own practice as a biologist and as a writer, the best way to hear the stories of the trees and to connect into this communication is to pick a particular individual tree and return it to it again and again with all of your senses open. What am I hearing here? What am I feeling through my sensitive fingertips on the tree's trunk? What can I smell here? How is the water moving through this environment? Returning to that tree again and again, befriending the tree.
And the tree, of course, uses very different language than we humans, but it still has its own language, its own ancient, interesting stories that we can connect to by opening all of our senses to its marvels.
JULIUS: Thanks for talking with us today, David.
DAVID GEORGE HASKELL: Thank you. It's been a great pleasure.
KIDS: (SHOUTING) Brains on!
[MUSIC PLAYING]
MOLLY BLOOM: Trees start as seeds filled with starch. That starch feeds the tree until it can make a root and a sprout.
JULIUS: The root pushes down into the soil to find nutrients and water.
MOLLY BLOOM: And the sprout climbs up above ground where it will eventually form leaves.
JULIUS: The leaves use photosynthesis to create energy from sunlight and air, which helps the tree grow even more.
MOLLY BLOOM: Over time, the tree's bark will darken and harden, and the tree will keep growing wider.
JULIUS: Trees grow blossoms and then fruit as a way to get animals to plant their seeds in new places.
MOLLY BLOOM: And trees can communicate with each other by sending chemical messages through the air and underground. That's it for this episode of Brains On.
JULIUS: Brains On is produced by Marc Sanchez, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: Our majestic fellow is Menaka Wilhelm. And we had production help from Bridget Asamoah and Christina Lopez, engineering help from Veronica Rodriguez, Mairead Campbell, and Evan Perkins. And special thanks to Sabina Kapp, Dianne Pater, Marley Feuerwerker-Otto, Josh Holt, Vicky Kreckler, and Sam Choo.
JULIUS: Brains On is a nonprofit public radio podcast. Your support helps us keep making the show.
MOLLY BLOOM: You can support Brains On and see our cool thank you gifts at brainson.org/donate. Now it's time for the Brains Honor roll.
[LISTING HONOR ROLL]
ROBOTIC VOICE 4: (SINGING) Brains On.
MOLLY BLOOM: We'll be back soon with more answers to your questions.
JULIUS: Thanks for listening.
ANNOUNCER 1: Brains On is supported in part by a grant from the National Science Foundation.
MARC SANCHEZ: OK, America, Roshambo. Whoever wins this gets to try out the cheese ray first.
MANEKA: Sweet beams of gouda, here I come.
MARC SANCHEZ: Ready?
MANEKA: Oh, yeah.
BOTH: Rock, paper scissors.
SAPENA: Tree.
MANEKA: Uh, Marc, did you say tree?
MARC SANCHEZ: No. That wasn't you? Whatever. Let's try this again.
MANEKA: Yeah, one more time.
BOTH: Rock, paper, scissors.
SAPENA: Tree.
MARC SANCHEZ: OK, I definitely heard tree.
SAPENA: Trees beat rocks because trees can eat sunshine and rocks can't.
MANEKA: I think the voice is coming from the window.
SAPENA: They beat paper because paper is just old trees, and old never beats young.
MARC SANCHEZ: Oh, behind the blinds, on the window sill. It's a sapling in a pot.
SAPENA: And trees beat scissors because when we are big and mighty, nothing can get through us. Trees win.
MANEKA: I don't think that's how the game works exactly.
SAPENA: Also, a talking sapling? Oh, please. You guys have talking bugs on your show all the time. Are you really surprised?
MARC SANCHEZ: Good point, sapling. Good point. Plus, Sanden has been experimenting with giving voices to inanimate objects. He's been paranoid that the staplers are plotting against him, and he wanted to get intel from the water cooler.
[JAZZ NOTES]
MANEKA: So what's going on, tiny tree.
SAPENA: The name is Sapena, and I'm just photosynthesizing and pondering the big questions. Like, if I was all alone in a forest and I fell down, would I make a sound? JK. LOL! Of course, I'd make a sound. I'd sound like this, ow, I fell over. Ouch, that hurts. Someone call a tree doctor.
MARC SANCHEZ: Hey oh! [CHUCKLES] You're pretty funny. You know, Molly is literally about to do an episode about trees right this very minute. We should totally have you on.
SAPENA: Me? What could I possibly talk about? Psych! I can talk about anything. I have so much to say. Want to hear my thoughts on ponies versus puppies, or the best kind of not? I'm a big fan of the figure 8, but a timber hitch--
MANEKA: OK, come here, tiny tree. Let's get you to the studio.
MARC SANCHEZ: OK, you guys go ahead. Let me just put this cheese right away. I'll get the-- whoa!
SAPENA: Whoa! You just turned the copier into cheddar.
MARC SANCHEZ: Oops, I guess my finger slipped. But, Menaka, if you hurry back, you can help me eat this.
[THEME MUSIC]
MOLLY BLOOM: You're listening to Brains On from APM Studios. I'm Molly Bloom. Brains On is public media. And public media is threatened like never before. To keep doing what we do, we need your help. We need you. Your donation can make sure Brains On sticks around through all this uncertainty. But we need you to give now. Like, right now. Please go to brainson.org/donate. Any amount is helpful. $10, $5. Maybe you like prime numbers and want to go for $83.
Just head to brainson.org/donate. That's brainson.org/donate. Thank you, thank you, thank you. Today I am very excited to welcome my co-host Julius from London, England. Hello, Julius.
JULIUS: Hello! We're also joined by Sapena. She's a tree sapling. That's what you call a small, young tree.
SAPENA: Hi. I'm Sapena, and I'm a blackjack oak.
MOLLY BLOOM: Today we're talking trees. And Julius, you wrote in to us a long time asking about trees. I'm just wondering, do you still think about trees?
JULIUS: Yeah, I do, I guess. I always wondered how they communicate and stuff like that.
MOLLY BLOOM: That's very interesting. Do you have a favorite kind of tree?
JULIUS: Um, I would have to say maple because of maple syrup.
MOLLY BLOOM: It's very delicious. When you think of a tree, what is the first part of the tree that you think of?
JULIUS: The first part of the tree I think of is the branches, because, you know, calculating the best way to get up it.
MOLLY BLOOM: Definitely. [CHUCKLES] Finding your climbing route.
JULIUS: Yeah, I think one of my favorite outdoor activities is probably tree climbing, so--
MOLLY BLOOM: Oh. Do you have any tree-climbing tips?
JULIUS: Upper body strength is really important.
MOLLY BLOOM: And do some training first.
JULIUS: Pulling yourself-- yeah, you have to train.
MOLLY BLOOM: What about you, Sapena? Do you think about trees a lot too?
SAPENA: Oh, yeah, I think about trees all the time. We're just so amazing.
MOLLY BLOOM: That makes sense. And you are in good company. Our listeners like pondering trees too.
MALCOLM: Hi. My name is Malcolm. My question is, what happens inside of a tree while it is growing?
OLER: Hello. My name is Oler, and my question is, how do trees grow.
SARAH: Hi. My name is Sarah, and my question is, how do trees grow?
CLAIRE: My name is Claire. How did little tiny seeds become big trees?
JULIAN: Hello. My name is Julian. I'm eight years old. My question is, how do trees grow? And while they're growing, how do the branches form? Thank you, and keep up the good work.
MOLLY BLOOM: Thanks, Julian. So, Sapena, since you're here, maybe you can help us answer some of these questions.
SAPENA: Totally happy to help. I'll take you through all the levels I've gone through to get here.
JULIUS: Levels?
SAPENA: Yeah. You can think of growing into a tree kind of like playing a video game. You complete level 1, and it's on to the next. Lucky for you, I've been recording my game on twig.tv. Check it out.
[BEEPING]
ROBOTIC VOICE 1: Level 1, seeds can't run.
[ARCADE MUSIC]
SAPENA: OK, so in this level, I'm a seed. I can't move. My foes--
ROBOTIC VOICE 1: The forces of chaos.
SAPENA: I have to avoid getting eaten or destroyed.
[BIRD SQUAWKS]
Oh, no, a bird! Phew, it flew away.
[BIRD SQUAWKS]
Oh, this level is almost all luck. But thankfully, I find a good spot to grow. I make it to--
[VICTORIOUS NOTES]
ROBOTIC VOICE 1: Level 2, start to thrive.
[ARCADE MUSIC]
SAPENA: As a seed, I have all the food and instructions I need to start life as a tree. This level is all about letting water into my seed and chomping on the starch stores in my seed so I can grow and get to--
ROBOTIC VOICE 1: Level 3, sprouting root.
[EXCITING ARCADE MUSIC]
SAPENA: So now I'm still chomping on starch from my seed because I can't make my own food yet. But I'm running out of starch. I have to break out of this shell. So I grow my first root.
[RUMBLING]
I am Root. And I grow a little shoot, my first little stem from the top of my seed too. I follow gravity to point my root down and follow sunlight to grow my shoot up. Once my shoot grows through the dirt into the air--
[VICTORIOUS NOTES]
ROBOTIC VOICE 1: Level four, first leaf.
[EXCITING ARCADE MUSIC]
SAPENA: This is a big one. I grow above ground and get my first leaves. So this level is when I start doing my own photosynthesis. That means I take in water, carbon dioxide, and sunlight, and make oxygen and sugar. I can make my own food from light. And thank goodness, seed starch is for plant noobs.
MOLLY BLOOM: Wow, thanks, Sapena, but we like seed starch.
JULIUS: Yeah. When people eat rice, they're eating seed starch. Flour is ground up seed starch too.
SAPENA: It seems a little weird to eat seed starch if you don't even grow roots or leaves. But anyways, those are all the levels I've beat so far.
ROBOTIC VOICE 1: Progress saved. Bark boss awaits.
SAPENA: I have some leaves now and a few different branches, and I think in the next stage, I do more growing. But I can't seem to beat the bark boss that unlocks my bark-growing powers.
JULIUS: Hmm, seems tricky.
MOLLY BLOOM: I think I know who can help. We have this tree museum on the 11th floor, actually. I bet we could figure out your next steps there.
SAPENA: For realsies? A tree museum? I mean, obviously, because trees are totally museum worthy, but, like, I could meet some other trees there?
MOLLY BLOOM: Yeah, all kinds of trees.
SAPENA: Oh, wow, wow. Yes, please. Let's go right now. Lead the way, and also, carry me because I have no legs.
MOLLY BLOOM: OK, Sapena, we'll go in a sec. But first, a little sonic sleuthing. It's the--
[WHOOSHING]
PRESENTER 2: (WHISPERING) Mystery sound.
MOLLY BLOOM: Are you ready, Julius?
JULIUS: Yeah.
MOLLY BLOOM: All right, here it is.
[CRUNCHING SOUNDS]
Any guesses?
JULIUS: Uh, If i had to guess, maybe somebody's eating something.
MOLLY BLOOM: Hmm, very, very good guess. Well, we'll be back with the answer and another chance for you to guess a little bit later in the show.
ROBOTIC VOICE 2: Brains brains brains on.
[FOOTSTEPS]
MOLLY BLOOM: OK, it should be right down this hall.
SAPENA: I see it, I see it, the Tree Hall of Fame. You guys, there it is.
[DOOR OPENS]
MOLLY BLOOM: Wow, this is actually much bigger than I was remembering.
JULIUS: Are we outside? Where is all that sky coming from?
HYPERION: Well, hello, down there.
MOLLY BLOOM: Uh, hi.
HYPERION: I am Hyperion, the tallest known tree in the world.
SAPENA: No way! I have your trading card. You're like a living high score. You are my hero.
HYPERION: Oh, (CHUCKLING) that's so nice to hear.
SAPENA: Yeah, you are a Sequoia sempervirens, or, you know, a Coast Redwood. You live in the Redwood National Park in California, and you're a whopping 380 tall.
HYPERION: You know your stuff, little one.
SAPENA: I am devoted to my stem education.
JULIUS: STEM? You mean Science, Technology, Engineering and Math?
SAPENA: What? No, dude. I mean stem, like studying trees every minute, because trees are the best. Oh, over there, is that--
GENERAL SHERMAN: General Sherman's my name. Largest living tree is my claim to fame. Pleased to meet you, fine friends.
MOLLY BLOOM: Wait, wasn't that other tree the largest.
GENERAL SHERMAN: [CHUCKLES] Silly human.
SAPENA: Yeah, silly human. Hyperion is the tallest known tree. General Sherman is the largest. That's measured by volume. It includes height and width.
GENERAL SHERMAN: That's right. I'm a giant sequoia living in Sequoia National Park, California. I'm certainly no slender sapling. If you're looking for lean lumber, you're barking up the wrong tree. [LAUGHS]
SAPENA: [LAUGHS] Tree jokes, it has tree jokes. Oh, mighty General Sherman, the tree, how can I grow big and tall like you and Hyperion?
GENERAL SHERMAN: Be patient, little sapling. It takes time, yes. But with luck, it will happen. [CHUCKLES] As you age, your bark will get harder and darker, but it won't be the bark that will make you thick and robust like us. [CHUCKLES] No. It's the stuff right under your bark called the cambium.
SAPENA: The cambium?
GENERAL SHERMAN: Yes, indeed. It's a woody plant tissue. And over the years, it will grow outward, making a tree wider and mightier. At the same time, your roots will grow deep into the ground, snaking their way through the soil to bring you water and nutrients and branches. You'll grow many more branches filled with sun-eating leaves. Those will feed you. I enjoy that quite a bit. Eventually, you'll start growing seeds of your own. Some may even end up in the soil where they'll grow into other trees.
SAPENA: Oh, wow. Oh, wow. I cannot wait.
GENERAL SHERMAN: [CHUCKLES] Well, treeing is not about speed. Indeed, I've been growing for over 600 years, and I've been at it for over 2,000.
MOLLY BLOOM: Wow, that's amazing.
JULIUS: Yeah, you guys are ancient.
METHUSELAH: Did someone say egg ship? I'd like to see an egg ship.
MOLLY BLOOM: Uh, what?
GENERAL SHERMAN: Ancient. He said ancient. Don't mind Methuselah there. Methuselah is the world's oldest known tree. A legend. It's a bristlecone pine that's been growing in the Eastern mountains of California for over 4,800 years.
METHUSELAH: Are the eggs riding the ship, or is it a ship made of eggs? [CHUCKLES, COUGHS] Either way, count me in.
GENERAL SHERMAN: Its hearing isn't great.
SAPENA: Wow, you guys have so much wisdom, so much bark. I'd love to learn more from you.
GENERAL SHERMAN: Then why don't you join us? We could talk tree stuff and, you know, our favorite types of knots from time to time.
SAPENA: What? I love knots too.
MOLLY BLOOM: You know, it seems like you're really happy here. Why don't you stay, Sapena? You know, lay down some roots. This is a perfect home for you.
SAPENA: Really? OK, I will. Thanks so much, Molly and Julius.
JULIUS: We should get back to the studio anyway. See you trees later.
MOLLY BLOOM: Bye.
SAPENA: Bye, Molly. Bye, Julius.
GENERAL SHERMAN: Farewell. Sad to see you leaf. [LAUGHS]
SAPENA: [LAUGHS]
HYPERION: [CHUCKLES] Come bark soon. We're rooting for you.
METHUSELAH: Maybe one of the eggs is a pirate.
ROBOTIC VOICE 2 Buh, buh, buh, buh, buh, buh, buh, buh, Brains On.
[EXCITING MUSIC]
MOLLY BLOOM: Right now, we're working on an episode all about astronauts, and we want to hear from you. What food do you think might be particularly tricky to eat while floating around in microgravity up in space? Record your answer and send it to us at brainson.org/contact.
JULIUS: And that's where you can also send us questions, drawings, mystery sounds, and high fives.
MOLLY BLOOM: That's how we received this excellent question.
ARTURO: Hi. My name is Arturo from Tucson, Arizona. And my question is, why does the moon change color sometimes?
MOLLY BLOOM: You can find an answer on our Moment of Um podcast, a short dose of facts and fun every weekday. Find it wherever you listen to Brains On. And keep listening.
PRESENTER 3: Brains On Universe is a family of podcasts for kids and their adults. Since you're a fan of Brains On, you'll love the other shows in our universe. Come on, let's explore.
[AIRCRAFT WHIRRING]
ROBOTIC VOICE 3: [PANTING] Its alien exercise hour! Hi yah! Hoo hah! While I stretch my snoodles and bounce on my trampolini, I'll listen to a new podcast. [LAUGHS]
[BUZZER]
I'm going to try Forever Ago, the best history podcast ever.
[BEEPING]
PRESENTER 3: To understand why anyone would think a TV show could change the world, we need to go way back--
[WHOOSHING]
--to America in the 1960s.
[ROCK AND ROLL MUSIC]
PRESENTER 4: Rock and roll was pretty new.
PRESENTER 3: Ford released the iconic Mustang muscle--
[BEEPING]
ROBOTIC VOICE 3: Zorb. Come back here, podcast. [BEEPING] Must listen to Forever Ago now!
[WHOOSHING]
PRESENTER 3: Listen to Forever Ago wherever you get your podcasts.
JULIUS: You're listening to Brains On from American Public Media. I'm Julius.
MOLLY BLOOM: And I'm Molly. Hey, Julius, I think we should get back to that mystery sound right away. Are you ready?
JULIUS: Yeah.
MOLLY BLOOM: OK, before we get back into it, before you said it was someone eating, and here's a clue. They're eating something that you might get from a tree. OK, here it is again.
[CRUNCHING SOUNDS]
Any new guesses?
JULIUS: Uh, I would guess an apple.
MOLLY BLOOM: You are 100% correct. That is the sound of someone eating an apple. Very good ears. Are you an apple eater yourself?
JULIUS: Uh, yes, it is one of my favorite fruits.
MOLLY BLOOM: What is your favorite way to eat an apple?
JULIUS: I always eat it from top to bottom, eating everything, really.
MOLLY BLOOM: Explain more about that. So, like, you start from, like, where the stem is?
JULIUS: So I put out the stem. I then eat it all the way from the top. I even eat the core. And then, you know, nothing left at the end.
MOLLY BLOOM: Do you eat the seeds too?
JULIUS: Yeah.
MOLLY BLOOM: Wow, you really like apples.
[MUSIC PLAYING]
And our listeners have some fruit questions as well.
LOUIS: My name is Louis from Adelaide, Australia. My question is, how does fruit grow on trees?
JUDE: Hi, my name is Jude from Charlottesville, Virginia. My question is, why does fruit grow on trees.
MOLLY BLOOM: So I went to the University of Minnesota Orchard where I met Jim Luby. He's a professor of horticultural science and also one of the scientists who brought us the honeycrisp apple, an apple, which, like the name describes, was bred to be very crispy and sweet.
JIM LUBY: This is the oldest honeycrisp tree in the world. It dates back to about the mid 1970s.
MOLLY BLOOM: So Jim knows his apple trees, and he showed me how these trees make fruit.
JIM LUBY: So if we want to go over to this tree here, what we can see here is a little shoot. And this shoot grew last year. And then at the end of it, it formed what we call a terminal bud.
MOLLY BLOOM: So picture a tiny little nub on the branch of an apple tree. It's called terminal because it's at the end of the shoot that comes off the branch.
JIM LUBY: And probably late last summer, it went from growing leaves on this little shoot to stopping growth at that terminal bud. And so those flowers start developing inside that little bud through the late summer and fall. Then the whole tree, of course, goes dormant, loses its leaves and goes dormant. And then the following spring, those flowers will continue to develop in the bud. The bud eventually breaks. We see those nice, white-pink flowers. Hopefully, a bee or other pollinator comes by and deposits some pollen from a different tree.
MOLLY BLOOM: Pollen is that yellow, powdery stuff you'll see in the center of flowers. All of the flowers on the apple tree have nectar and pollen to attract bees to them. But that pollen also has another purpose. It can accidentally take pollen from one tree's flower to a flower on a totally different tree. That will fertilize a cell in that flower, and it will start growing a seed. And around that seed, fruit cells will start growing.
JIM LUBY: The fruit will start enlarging. Also, during the summer, it's packing lots of starch into this fruit. And eventually, as the fruit ripens, that starch will be converted to sugar. And that's what you and I would recognize as the sweetness of an apple.
MOLLY BLOOM: But it's worth it, because animals who want to eat these apples will then help spread their seeds around by gobbling up apples and pooping out the seeds somewhere else. Then, from that humble beginning, a new tree will grow. The apple trees native to North America are tiny crab apples because they were eaten by smaller animals. And all those big apples that we think of as well, apples, those can trace their roots back to Kazakhstan, where they were eaten by bears.
JIM LUBY: And I've been actually over to Kazakhstan. And what you'll see is some-- you'll see brown bear dung, and it's full of apple seeds.
[MUSIC PLAYING]
MOLLY BLOOM: I don't know about you, but I find trees very calming to be around. My daughter hugs every tree she sees when she's walking down the street. I want to know, Julius, do you feel a connection to trees? I know you climb them. But have you ever hugged one, or how does being around a tree make you feel?
JULIUS: I know that they give me oxygen. They basically keep us alive. So for that, I'm grateful. So I suppose, you know, I'm happy they're around.
MOLLY BLOOM: I find it like-- I don't know. I just feel like I've. I slowed down a little bit when I'm near a tree.
JULIUS: Yeah.
MOLLY BLOOM: Trees do have a certain magic. They can't talk like we can.
JULIUS: Except Sapena and those other trees.
MOLLY BLOOM: Right. Well, most trees can't talk and they can't get around, but they're definitely alive. We wanted to know more about what they're up to, so we called David George Haskell.
JULIUS: He's a biologist at Sewanee, the University of the South, and he wrote a book called The Songs of Trees. Welcome, David.
DAVID GEORGE HASKELL: Thank you. It's a delight to be with you.
JULIUS: Is it true that trees use underground signals to communicate with each other?
DAVID GEORGE HASKELL: Absolutely. This is one of the revolutions in biology of the last few decades, is that we used to think trees were solitary individuals, each doing their own thing, deaf to the world. And now we know that they're engaged in this intimate conversation, both below ground and above ground with other trees, but also with other organisms, with the insects and then the bacteria and fungi in the soil as well. So they're very chatty organisms. They are indeed communicating, but of course, not using a language as a human language, but using their own tree method of communication, which is mostly through the medium of chemicals.
JULIUS: Cool. So can a tree tell when another tree needs help, like, when it's being attacked?
DAVID GEORGE HASKELL: Indeed, it can. Now whether the other tree is able to provide any help or not really depends on the situation. But if insects, for example, attack one tree in a forest, the other trees around it will learn of that attack and will defend themselves before any insects hit them. And they know this through a couple-- at least, a couple of different means. One is through airborne chemicals, little aromatic molecules that drift out of the injured tree's leaves and waft away into the air.
And the leaves around that injured tree then receive those chemicals. They smell them through their leaves because the leaves, of course, are open to the air. That's how they function. They draw in air through little breathing pores. And with that air comes these little alarm chemicals. The other method is below ground. It seems that chemicals are moving from one tree to another via pathway that involves the tree's roots, that are connected to fungi below ground, that are then connected to more tree roots, so that there's a whole hidden network of chemical conversation happening under the ground, as well as in the air.
JULIUS: Why do trees communicate? Because if they've got all these self-defense mechanisms, what is the need of actually saying if some insects are attacking you-- like, why aren't they solitary figures.
DAVID GEORGE HASKELL: So in this way, they're analogous to human communication. Why do we talk to one another. Partly, it's to learn things that are going to be helpful to us. And through experiments, monitoring the communication of trees and what they gain, people have found that trees that are-- and not just trees, other plants as well that are communicating one to another can protect themselves from drought. They can deter herbivores more effectively. They can get more carbon and nitrogen into their bodies. They can receive advance warning of what's happening in the forest.
JULIUS: So do you think that someday people will be-- can learn to understand tree communication? Like, is there a simple thing we can do to understand it?
DAVID GEORGE HASKELL: I think people have been doing this for thousands of years. Trees center in many of our important stories about meaning. Think about the tree of the knowledge of good and evil, or the tree under which the Buddha was enlightened. We understand in our culture that trees are symbols of meaning and understanding and wisdom. So we've been listening to them through culture and literature and poetry for many centuries. Now science is catching up and teaching us new things about how trees can connect one to another.
I would recommend, and this has been my own practice as a biologist and as a writer, the best way to hear the stories of the trees and to connect into this communication is to pick a particular individual tree and return it to it again and again with all of your senses open. What am I hearing here? What am I feeling through my sensitive fingertips on the tree's trunk? What can I smell here? How is the water moving through this environment? Returning to that tree again and again, befriending the tree.
And the tree, of course, uses very different language than we humans, but it still has its own language, its own ancient, interesting stories that we can connect to by opening all of our senses to its marvels.
JULIUS: Thanks for talking with us today, David.
DAVID GEORGE HASKELL: Thank you. It's been a great pleasure.
KIDS: (SHOUTING) Brains on!
[MUSIC PLAYING]
MOLLY BLOOM: Trees start as seeds filled with starch. That starch feeds the tree until it can make a root and a sprout.
JULIUS: The root pushes down into the soil to find nutrients and water.
MOLLY BLOOM: And the sprout climbs up above ground where it will eventually form leaves.
JULIUS: The leaves use photosynthesis to create energy from sunlight and air, which helps the tree grow even more.
MOLLY BLOOM: Over time, the tree's bark will darken and harden, and the tree will keep growing wider.
JULIUS: Trees grow blossoms and then fruit as a way to get animals to plant their seeds in new places.
MOLLY BLOOM: And trees can communicate with each other by sending chemical messages through the air and underground. That's it for this episode of Brains On.
JULIUS: Brains On is produced by Marc Sanchez, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: Our majestic fellow is Menaka Wilhelm. And we had production help from Bridget Asamoah and Christina Lopez, engineering help from Veronica Rodriguez, Mairead Campbell, and Evan Perkins. And special thanks to Sabina Kapp, Dianne Pater, Marley Feuerwerker-Otto, Josh Holt, Vicky Kreckler, and Sam Choo.
JULIUS: Brains On is a nonprofit public radio podcast. Your support helps us keep making the show.
MOLLY BLOOM: You can support Brains On and see our cool thank you gifts at brainson.org/donate. Now it's time for the Brains Honor roll.
[LISTING HONOR ROLL]
ROBOTIC VOICE 4: (SINGING) Brains On.
MOLLY BLOOM: We'll be back soon with more answers to your questions.
JULIUS: Thanks for listening.
Transcription services provided by 3Play Media.
