The Wonder of Trees - Dame Judi Dench, Tony Kirkham and Tristan Gooley

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BBC Sounds, music, radio, podcasts.

Hello, you're about to listen to the Infinite Monkey Cage.

Episodes will be released on Wednesdays wherever you get your podcasts.

But if you're in the UK, the full series is available right now.

on BBC Sounds.

Hello, I'm Brian Cox.

I'm Robin Inks, and this is The Infinite Monkey Cage back for a new series.

The question, of course, is always: if a tree falls in the woods and there's nobody there to hear it, does it make a sound?

And if Robin Ince is invited to a Royal Institution Christmas lecture and his head is placed inside a giant magnetic pulse generator, does he make a sound?

The answer to that is no, genuinely from experience.

I had a magnetic pulse on the right-hand side of my brain while doing Jabberwock.

Twas brilliant and the slithy toveted gar and gimbal in the wooh, and that was what happened and Brian now can't get hold of that machine but he would love to shut me up with my motor region.

Now even I know that even by the standards of the Internet Monkey Cage that's an avant-garde introduction but the reason we made it is today we are at the Royal Institution and we're talking about trees.

So you see it made sense.

And this is one of the most famous lecture theatres in the world.

And more than that some of it is made of wood as well isn't it which kind of connects with the leaf it now.

Leaf it.

Now, when I said leaf it, I'm going to make this clear.

I didn't want to put that in the script, but our producer loves puns.

So if you'd like to complain about that pun, don't send them to me.

You'll hear the producer's name at the end of the show, and we'll give you a home address.

Throughout the first half of the 19th century, Michael Faraday stood in this very spot and delivered lectures on electromagnetism, the electric generator, the electric motor, which he invented in this building.

And which the BBC are still using today to power this show.

Humphry Davy, Sir David Attenborough, Carl Sagan have all delivered lectures here.

So it's a wonderful place to begin the new series of The Infinite Monkey Cage.

So today we are going for a walk in the woods, something that, of course, normally annoys Brian, in particular in the spring, summer, and autumn time, because it gets in the way of all the really lovely stars.

I can't see it because, oh no, look, the yew trees in the way.

Oh.

How do trees compete in the woods?

How have trees adapted to the changing environment?

And indeed, what is a tree?

We're finally asking.

That's going to be a good question.

185 episodes of Finally We Ask, What is a Tree?

We're beginning to get somewhere with this science business.

Today, we are joined by a reader of trees, a leader of trees, and a queen of the trees.

And they are.

My name's Tony Kirkham.

I'm retired after 43 years of managing the Arboretum at the Royal Botanic Gardens Kew, and my favourite tree is the Dorne Redwood, Metsechoia glyptostraboides.

I'm an actress, Judy Dench, and I have a passion for trees, absolute passion, and my favourite tree is an oak.

Also, it is a family name of ours.

Alas, not my immediate family, but my cousins have all got oak in their name, which seems very suitable.

I like it a lot.

Hi, I'm Tristan Gooley.

I'm a natural navigator and author of books about clues clues and signs in nature, most recently how to read a tree.

And my favourite tree is an unremarkable beech tree, which taught me how to use bird poo as a compass.

And this is our panel!

Okay, Tristan, we have to bite, don't we?

How do you use bird poo as a compass?

Well, my work is about observing, but in particular, looking for asymmetry.

So everything in nature that I've found is asymmetrical, whether it's a tree, the sun, or everything in between.

And I noticed on one of my walks that there was bird poo, but mainly on one side of the trees.

And I paused by one tree and I tried to unravel the mystery.

And by the time I'd solved it, I'd gone through astronomy, botany, ethology, forestry, meteorology,

looked into the interconnectedness of nature, and I feel, ridiculous though it sounds, got a small glimpse into the meaning of the universe.

But to answer your question,

the birds are perching on branches and we get more branches on the side of the tree that gets most light.

And in this part of the world, that is the south side because the sun is due south in the middle of the day.

There are lots more levels to it, but that was the start of that fun investigation.

Brilliant.

So next week's episode is what is bird poo?

We're going to keep moving.

And well done, Tony, by the way.

I think that was very impressive.

You yet again found out that Radio 4 listeners, they do love a bit of Latin.

Oh, did you hear that sound when you got all Latin-y?

They loved it.

And that was the first tree that I learned at 10 years old.

Someone gave me a book, knowing that I was interested in trees.

I went straight to the index, like you do, to look for the longest Latin name.

I learnt it off parrot fashion, didn't know what it was, had no idea what the tree was.

And little did I know that in 1996, I'd see that tree in China growing on its own as a single specimen.

Well, if there's any lull in the show, you know the trick, just burst out into Latin.

We'll be fine.

That's a coin.

Tony, has everybody laughed?

They thought it was a joke, this question, what is a tree?

Yeah.

But I'm hoping you say that's a good question.

No, it is a good question, and there are lots and lots of definitions.

Basically, a tree is a woody perennial that can do something that we call secondary thickening.

So it produces annual rings each year and gets larger.

It can be broadleaf, it can be a conifer, it can be deciduous, it can be evergreen, and it can have several trunks.

The Oxford English Dictionary suggests that there's only a single trunk, but of course, there are multi-stemmed trees, and then they can vary in size from a birch in the Arctic that's about six inches tall to a coarse redwood, which is the tallest tree in the world in California that's 115 meters tall.

So, so if you look at a woody, like a woody hedge, it's absolutely ridiculous question.

Why is a hedge tree?

Woody hedge, by the way, is a really great name for a 1960s beef hedge.

Ladies and gentlemen, please welcome ready, steady, go.

Woody hedge.

Why is a private hedge not a tree?

What is it that rules it out?

I thought this was a scientific programme.

Well, that's a really good question.

No, it's a really good question, Brian, because when is a tree a tree?

When is it not a shrub?

And so things like hollies,

hazel, privet can be trees if they get large enough.

So some of the shrubs, we usually say if they get over several meters tall and start to put on a good trunk and live for you know maybe over 10 years, then they can become a tree.

So there's a lot of confusion between you know, when is a tree a tree and when is a shrub a a shrub and when do they change?

We're so close to being a philosophy programme.

Judy, how do you feel about that definition of a tree?

Because obviously, anyone who saw the wonderful documentary you did, you have a real true passion for trees, you have woodland.

I don't know why this happened, but when I was really a small girl,

seven or eight, maybe, I used to get irrationally upset when I saw lorries with trees on them.

Then I used to, I went through a stage where I thought I once remember saying to my parents, I think we're in an upside-down world because I think they're the roots up in the air.

They said, no, pull yourself together, Judy.

Come on.

But then it came to the fact that I went to Stratford in 1962 and walking through the Bancroft gardens one day, I saw a tree and it had on it the name Vivian Lee.

and it said under it, alas unparalleled, which is a Shakespeare line.

And I thought, this is the most marvellous thing to do.

But I kind of put it in a notebook.

And it was only till, you know, 40 years ago when we moved to our garden that I suddenly thought this is it this is what I must do I must plant as many trees as I can and there was many different kinds and two two friends who have died and how do you choose them what which trees do you decide to put there it's very hard sometimes sometimes I think they actually look like them do you know

you know I just think you have to somehow match the character but I just find such delight in the fact of having trees in my garden or seeing them everywhere you know well you're very knowledgeable on trees judy i remember you taking me around the garden and uh you showed me a tree and i remember you saying it was like the person that you'd planted it for because it was a birch with grey bark and you said he was very he was always very grey

kristen how do could you talk us through the life cycle of a tree how does it begin how does it grow how does it become a tree well in my work i'm looking at things through quite a strict filter so i'm not looking for the complete scientific chapter and and verse.

I'm looking for what helps me understand the clues I'm going to find.

You know, those time-lapse videos we see when we see something growing incredibly sort of fast and sort of working its way upwards.

And perhaps when we were kids, we grew sunflowers, and we get this idea that the top of a plant moves upwards, and it makes us think all the parts of a tree move upwards.

But a big breakthrough for me, and all my work is I'm standing on the shoulders of giants and scientists and researchers, was when I discovered that trees have two main stages of growth.

They have that time when they're working their way upwards, and it is like the sunflower.

That's the primary growth.

They then have the secondary growth, and that's when they put on bark.

And at that point, the trunk doesn't move upwards at all.

And the most sort of fun way of thinking of this is: you know, when you see graffiti on the trees, quite often it's romantic and you know, Leo 4 Gemma or something like this, and we shouldn't do it, it's not good for the trees, but it's helpful for this particular example.

That graffiti doesn't move.

And for me, that was quite an eye-opener because I've always thought of all plants moving upwards.

But the second the bark is there, it will grow fatter, but it won't go upwards.

So a branch, for example, doesn't move up.

That was a really, when I first, when I was reading your book and finding out about that, it's such because we've got a Christmas tree in my old dad's house and it was four foot tall.

And now it's terrible.

It's an absolute nightmare and it's ruined the whole village green because it's all dark now because of the size of the tree.

But I suddenly he put a pulley on it to put up Christmas lights until that was impossible.

And I've realised when I was reading that, the pulley is still in the same position.

So now it's halfway down the tree.

What was once at the top of the tree?

And that is, if, as you said, it's such a counter-instinctual idea of how we see the process of nature.

Yes, we get these ideas at a very, very young age, and it takes a little bit of a shift to actually sort of overturn them.

But when we do, it makes sense of so many things.

It explains the shape and the patterns we see in the tree.

So we imagine that the branches start at the sort of ground level and moving upwards.

But actually, what the tree is doing is constantly growing new branches higher up and then lopping off the ones it doesn't need lower down.

And what we see is the end result, but we imagine an entirely different story.

But the great thing about trees is that we can age them by these annual rings because they produce one a year.

And we always over-egg how old trees are.

You know, we're, I'll not say that we're competitive in the tree world,

but we are very competitive.

And in our gardens and arboreta, we always want the biggest, we want the tallest, we want the oldest.

And, you know, part of my enjoyment now now in retirement is going around the UK, going round the world.

You know, just come back from America, looking at trees, looking at old trees, looking at the big trees, and looking at those record breakers.

And we have people in the UK who go around measuring trees as a job.

And this information is going to be really important as we go into the you know this climate change to see which trees are going to be the best to grow in our climate, which which are growing the fastest, which are growing the biggest, which aren't growing at all.

And that will start to tell us which trees we need to be planting for the future.

Given that you mentioned the records, so can you give us a sense of, because you said the oldest tree, the tallest tree.

So you should tell us.

If you ask my children, I've got two children, and I took them on a holiday to California to see the biggest tree in the world, the oldest tree in the world, and the tallest tree in the world.

After the second tree, my daughter lost the will to live.

I mean, she was only 13, 14, and it cost me two days' retail therapy in Macy's.

But the tallest tree is on that west coast of the Pacific West Coast of North America, in California, just creeps into Oregon, and that's a coastal redwood, Sequoia Sempavirans.

And the tallest tree, they have names, so the tallest tree is called Hyperion, and it's 115.7 meters tall.

We love a very tall tree, you and I.

We did when we were

must talk about that one in Borneo, yeah.

But

the biggest tree in the world is General Sherman, which is a giant redwood, Socorodendron giganteum, and that's over the Sierra Nevada in California.

And you know, these are huge trees.

And just to give you an example, General Sherman lost a branch a few years ago, and that branch is bigger than any redwood outside of California.

And it's still the biggest tree in the world.

So, you know, these are monsters.

And then the oldest tree in the world is a pine, the bristlecone pine, Pinus longieva, which means long-lived pine.

And

that's between four and five thousand years old.

And we know that because we've counted the annual rings by doing what we call increment boring.

So we can bore into the tree, take a core out, and then count the annual rings.

And that's in the White Mountains or Death Valley, the only tree that will grow there.

What was the tree you climbed in Borneo?

What was the name of the tree?

Gigi, I thought you remembered the Latin name of it.

It was a yellow Maranti.

a yellow maranti wasn't it it was a very very tall tree

it was and you went 30 meters up it i did on the end of a rope yes hauled by a young man called unding yeah

he was about 15 i think probably

we were looking at the biodiv all the different biodiv types of biodiversity in the borneo rainforest which was amazing

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Everybody gets excited by tall trees, as we should do, but in my strange world and strange perspective, the short trees are often telling us some interesting different stories.

So the wind, when it buffets the trees, triggers, since you're having fun with words down that end, I'll join in.

It triggers a botanical process called thigmomorphogenesis.

Touched...

Oh, man.

I heard a metal gauntlet slapping a cheek there.

Stand by.

I believe I've gone a bit towards the Greek, not the Latin, but I might be wrong there.

But the fun part of it is this is touch change growth because again, trees don't know the world they're growing into.

So if they're in a sheltered valley, they grow taller than if they're on a windswept hill.

And in natural navigation, we can use this because the shortest trees will be on the southwest side of woodland because that's the side that gets the prevailing gales.

So if you look at woods on a hill from a little distance, look for the shortest side, and that, through thigmomorphogenesis, forgive me, will be the southwest side.

I have now got to work out how I can just drop figmomorphogenesis into conversations, and I presume that's why I'm going to have to start working for the Forestry Commission.

But I wanted to ask you, Judy, there was something that Tristan was saying a little bit before,

which was about this kind of self-mutilating branches almost, this action that is going on with trees.

And when we look, and you have this wonderful woodland, and I think people without, you know, without knowing a little bit more, would just see a wood as a place that's almost stationary, that there's a kind of, you know, silence and not much movement.

And yet, when you hear these stories, suddenly when you look at those woods, they are a place of perpetual action.

We might not be able to observe it, but we know that something lies within it.

Yes, and I did a programme about trees, and something I absolutely never knew, it was early spring, couple well, three years, maybe, four years ago.

We went to a woodland where there were a lot of bluebells, and the person I was with had brought a kind of stethoscope, which they put against the trunk, and I couldn't believe it.

I could not believe the force of water rushing up the trunk.

Especially, it's very comforting when you look in the winter and it's all bare and you think, oh, the trees have gone to the.

It's very comforting now to me to know what's going on inside.

They're doing all the time.

They're exhausted at the end of the day.

It was a revelation.

Is there any limit to how long a tree could live in principle?

You said that we're talking about 5,000-year-old trees here.

What determines the lifetime of a tree?

I think it's a really difficult question to answer that, Brian.

The 5,000-year-old bristlecone pine could live for another 5,000 years.

So we're going to have to stay around for a bit to

find out.

And there are some trees like the London Plain, which is a hybrid where we've crossed a North American species with a Mediterranean species, and the the originals are still growing and that was in the 1600s and we still don't know how big the London plain will will get.

So does it tend to be the environment and environmental factors that kills them ultimately or just being blown down in gales?

Or man?

The threats are logging, illegal logging, etc.

Pollution.

Climate change is going to be a determining factor.

Judy, can I sort of say, just because Tony was there talking about the age of trees?

And is that part of the connection?

Because before we came out, I was talking about in the village I was brought up in, there's an oak tree that's 500 years old.

And from the time that I was very small, I could just imagine, you know, all of those different children that might have danced around there, and all those adventures, and all the climbing on the branches.

And it seems to me that trees are wonderful for helping us to get that sense of all that time.

I agree.

I mean, I just love the idea of planting trees, which I

haven't got a woodland actually, but I have six acres only, but I just love the idea of planting trees that somehow represent the person you're missing.

I think it's an important thing that you can on a birthday or an anniversary, you can send a picture of that tree to the relative of Overtis and say, Look, what's happened to your tree?

You know, recently I sent a picture to Greg Doran because of Tony Scherdy a couple of years ago, and and I put such a small, little tree into my orchard and it's now way above my height.

And I think that's quite a comfort to somebody.

I think it's a Nunhead Cemetery has this in one of the corners, a wooded corner, there's a tomb that has been broken open by a tree breaking through it.

And you can't help but feel going, not quite yet, I'm not quite ready yet.

Tristan, your book is How to Read a Tree.

When you see a tree, as Judy said, that there's a history to the tree.

How do you begin to look at a tree and try to understand what it's been through for those hundreds of actually sometimes thousands of years, I suppose?

Yeah, so I love the idea, and we can all do it now.

Imagine a tree, and then if you step out and look at the very first tree you meet and think, is that identical to the tree I imagined?

And the answer will always be no.

And there will probably be hundreds of small differences.

And every one of those differences is a clue because it is a reflection of the world that that tree has experienced, its story.

So, for example, if it has on one side of the tree, the leaves might be smaller than you're expecting, and that might be the south south side.

There's more light there, the leaves become smaller, thicker, and lighter in colour, sun leaves on the south side.

Or we might find that the leaves have a very sort of pointed tip, and that's telling us that the area is wet because leaves have evolved to shed rainwater because it's a burden.

So, there are hundreds of these little differences.

I mean, if you just sketch a tree, it will not look like the tree you meet.

And so, that's what I'm always thinking.

So, my work really is putting on the detective hat and thinking, what is the reason?

There is always a reason.

Randomness sort of pops up in the quantum world and things like that but in in terms of tree shapes and patterns it really doesn't i was going to say honestly i was going to say have you ever met a tree that stumped you and i thought i can't stop

i really genuinely can't stop

send your complaints to our producer even that was her using telepathy to get a pun in his head

do you have any uh trees you've encountered where you say i i don't understand how this has come to be the way that it is yeah i mean the the joy for me is i i follow the idea that there will be a reason and i actually now I'm at the point where I love it where it's a real mystery.

Some of the best ones come in actually in urban environments because we tend to sort of mess around with trees quite a lot when in towns and cities but also you get quite fun patterns.

There was a tree I met on holiday once that was growing in the

we've met we've been living together for many I granted

I'll tell you what it takes a lot for this audience to go that's weird so

well done I I am weird I

grant And I looked at this tree that I'd met and

it was growing the wrong way in Inverticomas.

Now nothing can grow the wrong way, but it took me ages to work out what was going on.

It was picking up light that reflected off a mirror glass building on the other side of the road.

So it was just doing the natural thing and growing towards the light.

But the reason that I was puzzled was because it, yeah, it was breaking all the rules.

Naughty tree.

Is there such a thing as a...

We talk about the British Isles, we think, as Judy said, the oak tree.

It's almost like a symbol in the British Isles.

Is there such a thing as a as a as a native tree to the British Isles?

What what are those native trees?

I mean, we we have a very small number of native species in the British Isles, actually.

You know, what is a native?

That's another question.

But for me, it's when Brexit first happened, eight thousand years ago.

When the channel when the channel was formed, when the channel was formed, yeah.

And any tree that managed to get to the British Isles from the continent before the waters broke, that's a British native.

And I suppose the oak is the iconic tree of the British Isles.

And the yew is definitely the oldest tree in Britain.

And we have trees that are thought to be between two and four thousand years old.

But the oak's been around a long time.

And the great thing about the oaks is how we relate them to historical events.

So my favourite oak tree is the Queen Elizabeth I Oak in Cowdery Park.

And I usually make two pilgrimages a year to see that tree.

It's a fantastic tree, totally hollow, thought to be almost a thousand years old.

And it's called the Queen Elizabeth I daughter because Queen Elizabeth I is supposed to have sheltered in it while she was out hunting.

Judy, do you remember the first time that you deliberately made a trip just to go and see a tree?

Because you know, there's that wonderful book, Meeting with Remarkable Trees, which I think helped introduce a lot of people as well.

Was there something you saw thought?

I don't remember.

My first recollection was raking pears off a tree that was in our next door garden and being told off for it quite right

but I don't remember I'm going to boast a lot now because I have just been given thanks to Tony a shoot of the sycamore gap tree

yes indeed

which I was overcome when Tony said this is going to be given to you.

So it was going to make Chelsea and it's been taken away again till the autumn because it's got to grow a bit more and then it's going to come back and be implanted.

I've decided I'm going to call it Antoninus because I thought that was Hadrian's son, but somebody said to me, That's not Hadrian's son, that's Hadrian's lover.

And I said, Well, either way,

son, lover, I don't care, that's who's going to come.

That was such an interesting story because

I think people would have been surprised at how emotionally they affected they were.

Because I remember the first time seeing Sycamore Gap, and it it really, it did have an emotional, you have an emotional reaction.

The landscape of it, the beauty of it, the loneliness of it, you know, that was an amazing connection.

And it's a place where people used to meet and were engaged under, were probably buried under, I don't know.

But, you know, it was such a beautiful tree.

It's the most photographed tree in Britain.

It's also, of course, the film Robin Hood with Kevin Costner.

Oh, yeah, it's just past Dover, isn't it?

I think in that film.

It's a short ride in the film.

At risk of making myself sound even weirder than I have done already,

there were a pair of yew trees on top of the Sussex Downs and they were chopped down by the landowner with good reason.

They were converting the land for pasture and yew trees and animals aren't a great partnership, but they assumed nobody would notice, I think.

And I was bereft because I'd spent years teaching people using these two trees the way the wind and the sun shape them.

They were my classroom for over a decade.

And I think that's, for me, that's the exciting thing how we can build a relationship with trees is instead of, I think it's fantastic when there are these landmark trees and we should all enjoy them.

But the trees we see every day do become remarkable when we just start asking ourselves questions like, why are the branches pointing that way and not that way?

Why are the leaves, you know, only in this place and not in that place?

And then we start to see its story and the relationship develops.

And yes, you then start talking about them like they're your friends.

See, we've talked a lot about trees in the British Isles.

So if we go to the southern hemisphere,

anyone who's been there will notice that they almost look alien.

Can you give us an idea of the trees that you find if you go right to the other end of the earth?

Right to the other well I mean if you go down to the southern tip of South America, then you get the monkey puzzles.

And the monkey puzzle we call the Marmite tree.

Some people love it as a tree, some people hate it, but it is an incredible architectural plant that and Fibonacci's number sequencing is based on how that tree grows, by that spiraling branch that gives it its strength to stand up.

And then you can go across to Australia, you've got the eucalyptus, the gums, and there are about a thousand different species of gums.

So I could start and tell you how to identify each one,

but we're going to be here for quite a few days.

But the tree that I suppose captivated most people's attention is the wallamai pine that was discovered in Australia in 1994.

We thought that became extinct two million years ago from fossil records of you know pollen grains.

And then suddenly in 1994 David Noble, a member of the Wildlife and Fauna Organisation in Australia, was canyoning in the Blue Mountains, 125 kilometers northwest of Sydney.

And he came across this tree that he didn't recognise, broke a piece off, brought it out and showed it to all the botanists who'd never seen it before, apart from fossil records and descriptions, and asked him

how small was it, with a little shrub.

And he went, No, it's 42 meters tall.

How had that evaded our attention for so long?

There are only about 70 trees in this canyon,

that's the only population that are being monitored and grown.

But we flooded the market with young wallami pine so that nobody had to go into that canyon to try and collect it and to raise money to protect the habitat that it grows in, because that's what we need to do.

And it prefers to grow in England than it does in Australia.

It's growing better with us than in Australia.

So you could.

So, Judy, if you said

I'd like to plant one of those,

so you can.

So, Tony.

I know what to get you for Christmas, Judy.

I'll get you a microphone.

How did you go about getting one of those?

Oh, well, you can buy them over here.

They are available in

all the nurseries.

Yeah, yeah, you can buy them in garden centres.

And it's well worth trying.

It is a beautiful tree, and its other closest cousin is the monkey puzzle.

So at Kew, I planted them next to the monkey puzzle so they could catch up on two million years.

Because they do communicate, so they could catch up on two million years.

You told me about the kind of communication that I'll never forget it, that trees have between themselves underneath the ground and they can signal if there's any kind of threat or something they can signal to another tree that's right the wood wide web we had

underground for trees yeah absolutely you're absolutely right Judy and and we we went into a woodland and and looked at this

mycorrhizal fungi that is like fiber optic cables that run from tree to tree and connect them all and send signals and tell each other what's happening.

And if there's a tree that's feeling a little peaky, a bit under the weather, then the mycorrhizal fungi can help it out and share other resources with them.

So trees are amazing things.

They survive for a long, long time.

And what we've got to remember is where they come from, from woodlands.

And

these woodlands are like social enclaves for trees.

There's quite a fun one above ground, I believe, with the acacias in Africa, isn't there, as well, where they've evolved this incredible defensive response.

Because when the giraffes start grazing on the acacias, they I forget the chemical, is it a tannin?

I don't know.

Do you know, Tony?

Yeah, it's a tannin.

And like, I think in most trees, when they come under attack from insects or animals, and they can increase the tannin levels in the leaves and the branches, so they become very bitter, and they can do it very quickly.

And what's amazing I found was that quite a few of the trees do that, and the giraffes have worked out that the trees are communicating through the hormones in the air.

So the giraffes have let frog that logic.

So they start at the downwind end of the row of acacias.

Yeah, yeah.

There's a question here about what we mean by life intelligence, because you said earlier the tree wants to do this, the tree, and of course, it's just a form of language, right?

We don't think these have agency as such.

But the more we talk about a woodland, for example, which you said, Judy, communication networks, it does begin to feel there's a almost a layer of life, a way that things cooperate together that we're just beginning to

glimpse.

But trees also send signals to us that we are totally oblivious to.

And I think if everyone goes out tomorrow and walks around a tree, those trees give off something called monoterpenes.

And they trigger things in our brain that relieve stress, relieve anxiety, improve our mental well-being, and make us feel good.

And there's evidence to show that if you've had an operation, say, for example, in hospital, and if you are in a recovery room and can see trees or be near trees, then your recovery will increase dramatically.

Being amongst the trees reduces stress until you discover, as I did at Kew Gardens, that walking over the roots compacts them, which then leads to trauma and branches falling.

So, if you find a path, a new path, most paths in the UK are older than the trees next to them, they're well established.

But if you find a new path cutting through woodland, have a look at the branches above it and you'll find they're really struggling because the path has compacted the roots.

This leads to bubbles, cavitations, that kills off.

And one of the things I didn't realise until researching the book was that the roots on each side of the tree are supplying that side of the tree.

And that was for me, it was a real eye-opener when you realise you see a new path and you can see the actual branches suffering above that path.

So, that after you've recovered from your illness, you can think about the

yeah.

Judy, can I just ask about that six acres of woodland you've got, how much did it start off with a plan?

It didn't.

I think that the thing I said about seeing the tree in the Bancroft gardens at Stratford kind of triggered off something in my mind of how lovely it is to actually be able to plant something to somebody who's not with us anymore and see that.

And Michael had felt exactly the same about that, and that's what started us.

So, I think we planted 80-something trees all over the garden, and there are, I'm afraid, many more to go in.

But I can't begin to explain how unbelievably satisfying it is.

Well, we all know because we appreciate them so much, but it is to see their growth.

And it upsets me about the paths.

That's very upsetting to know the paths past a tree kind of upsets or worries them.

There is one positive spin, which is that the roots have sort of two parts.

So, if we think of the edge of the canopy, that's the drip line.

That's very, very sensitive.

And if people start walking or going over on mountain bikes and things like that, the tree will suffer quite significantly.

But closer to the tree, it's more structural roots.

And there, you can actually have an ancient path, which

near where I live, there's an old Roman road, and there are these mighty beech trees, and the two are right next to each other, And people are bombing up and down, walking and cycling, and the trees are absolutely fine.

So, if you get close enough to the trunk, you're sometimes doing the tree less harm.

I love strange stories

of trees.

And there was one that I was reading in, I think it's Nicholas Fern's book of philosophy, where he starts off telling the story of someone who, when they died, they were considered very unpopular with the village, so they were buried outside the churchyard.

A hundred years later, they went, they checked the records, went, actually, he wasn't such a bad person, we should put him in.

And then they dug down, there was an apple tree that grew just near the grave.

And when they opened the coffin, there was no body as such.

There was just a human-shaped root of a tree, which I love as an idea.

And the idea that all of those apples that had been eaten by those people.

And I'm fascinated, you know, from any of you, those kind of moments, again, another bit of that connection.

First of you, I suppose, is that possible?

Absolutely, yeah.

I mean, they'll look for the

easiest route.

Sorry, another pun.

The The easiest area to break through soil.

I've seen London plain routes that have been excavated in London that have 90 degree angles where they've come and dug the road up to replace water pipes or you know gas pipes, put the soil back.

The soil's a lot finer and looser than the compacted soil around.

So they've literally followed down the trenches and then you get these routes with 90 degree corners.

So yeah, there are opportunities and they'll look for the easiest option.

option.

You know a lot about trees, Tony.

I think we can.

But I always like to ask this question of real experts.

Are there questions that are burning questions that we do not understand?

Is it about discovering new species, or is there something about trees themselves that you would think?

I would love to know that.

I'd love to know more about what goes on underground and

how trees communicate.

I mean, we know roughly how they communicate.

I think I'd like to know a little bit more more about, you know, how they do and how they support each other and help each other and survive.

You know, I'd love to be able to talk to

Methuselah in the White Mountains and just find out what it's seen and what it's experienced that we'll never know.

What about for you, Judy?

Yes, the things you'd still like to know about the trees.

Oh, there's no end of things I want to know about trees.

I just love seeing the change of them.

I love learning about them.

I never get tired of it.

And actually, we did have a wonderful afternoon once when Tony came down to the garden and we measured an oak that was in my garden.

And Tony said that would have been here during the Battle of Waterloo.

I just love that fact about it.

I mean, they're like people to me.

Well, they're people, they represent people, but they are actually like people.

They're all so different.

They all behave in such extraordinary ways.

Suddenly, throw out something you know, no idea about the shape of it changes.

May I ask about this?

One of my favourite actors was Ian Richardson, and I believe you have, and there's from that wonderful line in Tinker Taylor Soldier Spy, where he's asking Smiley to give some money to a young man he's been having an affair with, and he just says, He was a cherub, but no angel.

And just for that alone, it's such.

And I just know you have a tree for Ian Richardson.

I do for Ian, yes, because we were at Stratford together in 1962.

The wonderful thing is that sometimes the trees look like the, I know it's daft to say, but they actually start to look like the people too.

When my grandson was born, we put an oak in, and

Sammy's going to be 27 on Friday.

Well, this oak,

I mean, it's so representative, or Sammy is so representative of the oak, they just look alike.

You don't think you'll be offended if I say that, Sam is a beautiful oak in my garden, but you know, you can have two, but that's also what I love about it, that you can have two trees, exactly the same family of tree, they will grow completely differently.

They look different.

They look different in the surroundings they are, or whether they're with their own kind.

I think that's the thing, though, isn't it?

What a lot of what this side of things we've been talking about is really you have to look at things for longer, because the longer that you look at something, the more you go.

I thought these were all the same, and that's part again part of the beauty of science and curiosity placed together is you find the personality that can lie in so many things which which we just morph together.

Tristan, for you, where are the mysteries left to be discovered?

Oh, infinite, which is appropriate for this, isn't it?

But I'd love to pick up on something that we've touched on there, which is that learning can, I don't think you use these words, but maybe it was this sense that kills the magic sometimes.

And for me personally, and I think for a few others out there,

you can get the magic back if we don't drown ourselves in technicalities, but instead do what I believe very strongly we were born to do, which is is to observe and understand to find meaning.

So what I mean by that is if you look at a river valley for example we can go in and try and identify down to species level every tree along that river and that could be a satisfying exercise but for me it's a lot more fun to step back and go oh it goes from pale to dark it's going from broadleaf trees to conifers.

Why?

Broadleaf trees out-compete conifers in moist environments, so they're going to do well near the river.

And then as you look up the side of the valley up the hillside, you see the broadleaf trees are getting shorter as you go up the valley.

Ah, that's because the wind is battering them as you go up, so they grow shorter to respond to that.

And then they start to give up, and the conifers do better.

And you start with tall conifers, and you look a little bit higher, they get shorter, and then they give up.

So you've actually got a tree altimeter there without knowing the name of a single tree.

You've understood how the trees are competing, how they're making their home, what they're telling you about the environment.

So for me, that's the happy zone.

We're learning, we're observing, we're finding meaning, but we're not actually sort of beating ourselves up with technicalities.

Oh, well, I hope everyone who's listening to this now, wherever you are, you know, you go for a walk in the park and just whatever tree it may be, you know, start that relationship.

And I don't think that does sound weird.

I think that is a beautiful thing.

It does a bit.

It doesn't sound a bit weird.

I'll tell you what, the day I'm told that I'm weird by someone who can't relate to anything that's beyond subatomic is the day I'm more than happy about that.

Now, we asked our audience a question, and today it was, what tree would you like to climb and why?

A small one because if if

because if I fall it's not far to fall gravity.

I like our more nervous listeners.

I would like

I would climb a poultry sentry holding pastry in the wintry pantry because poetry

head and tree

because it yes, because it takes 28.5 minutes to get to the punchline of this joke.

An infinite monkey puzzle tree, as with Brian, I would appreciate the gravity of the experiment.

A redwood tree, because it has strong branches and I could attach two ropes and a seat.

After all, swings can only get better.

So, well done, everyone.

Well done.

Here we go.

My family tree to stop those cousins marrying, yes, I'm Irish.

Thanks to our guests, Tony Kirkham, Tristan Gooley, and Dame Judy Dench.

Excitement

doesn't end because next week's show is all about snakes

and ladders.

We're doing a whole show about board games and that's not a lie.

Thanks very much.

Bye-bye.

Bye-bye.

Feel now nice again.

I'm Helena Bonham Carter, and for BBC Radio 4, this is History's Secret Heroes, the new series of rarely heard tales from World War II.

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Of course, it was dangerous, but danger was his friend.

Helping people was his blood.

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