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I'm exploring the fascinating world of plants,
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from the most bizarre to the most beautiful.
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With new technology and in 3D,
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we can reveal aspects of their lives
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that are otherwise hidden from us.
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We can change time
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to discover a dynamic world of constant motion.
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We can change dimension
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to watch them interacting with insects.
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We can analyze how they communicate
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with color,
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with scent,
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even heat.
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And we can discover how fungi
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are not the enemies of plants,
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but their essential partners.
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And we can watch all these dramas
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unfolding in just one unique place,
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outside in the gardens
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and inside of these spectacular pavilions of glass -
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the Royal Botanic Gardens of Kew.
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Kingdom of Plants with David Attenborough
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Our senses
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match what is important to us.
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Our eyes can detect just tiny little movements
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and see best during the day.
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Our ears
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can detect the frequencies of the human voice.
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But there are many things that are very important to plants
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that we can't detect.
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This is an exploration
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of that hidden world.
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Solving The Secrets
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Plants may seem passive and inactive,
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but, in fact, they move.
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These are among the most mysterious -
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sundews.
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The leaves, like those of other plants,
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use sunlight to help them grow.
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But their glistening tentacles
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get food in another way.
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They are traps.
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Plants, to grow properly,
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needs sunlight
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and water,
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and minerals and nutrients which they get from soil.
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But in some parts of the world,
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in swamps and bogs for example.
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there are very few minerals and nutrients in the soil.
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So plants have to get those things from somewhere else.
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And they get them from the bodies of dead animals.
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Each tentacle is tipped with a glistening droplet.
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It may look like nectar
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and, indeed, many insects seem especially attracted to it.
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But it's not.
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It's a glue.
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It not only holds the insect fast,
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but clogs up the tiny holes on its flanks
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so that it can't breathe.
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Time-lapse cameras reveal
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that tentacles that are not touched by the insect
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now start to bend towards it.
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How they detect the insect's presence
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we still don't know.
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Finally, the sundew begins to fold its whole leave
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around its prey.
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There will be no escape
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from this lethal embrace.
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Now, the plant liquefies its victim's internal organs
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while it's still alive
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and absorbs the nutrients through its leaves.
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Other carnivorous plants don't require special photography
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to show how fast they can be.
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Darwin described this plant
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as one of the most wonderful in the world.
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It's a native of the coastal plains
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of North and South Carolina in America -
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the Venus Flytrap.
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It catches insects with booby traps.
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At the top,
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the leaves are baited with a sweet nectar.
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But lower down,
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there are a few upright bristles -
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triggers.
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Many things might accidentally touch one of them,
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so a single touch has no effect.
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But a fly crawling around on the leaves sipping their nectar
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is likely to touch more than one of the bristles.
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And if it touches two within 20 seconds,
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that's different.
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It's thought that the trigger hairs work
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by releasing a rudimentary electric impulse.
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The victim's desperate attempts to find a way out
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simply trigger more hairs
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and encourage the trap to close even more tightly.
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The plant begins to release juices
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rich in hydrochloric acid.
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It will take ten days to completely digest its meal.
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But there's a carnivorous plant
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that moves at even greater speeds.
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It lives in the hidden underwater world
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of lakes and ponds.
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It's called Utricularia,
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bladderwort.
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These tiny wrigglers are mosquito larvae
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and they are among its prey.
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The bladders that give the plant its name
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are not floats.
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They, too, are traps.
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Each bladder contains a partial vacuum
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and has a one-way entrance.
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By slowing down the action 240 times,
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we can see how they work.
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With the slightest touch,
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the door flies open inwards,
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sweeping the prey inside.
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It all happens in less than a millisecond.
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Utricularia is the plant world's swiftest killer.
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But most plants, of course,
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move very slowly indeed.
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Our cameras over the year
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can show just how dramatic
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such seasonal changes are.
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It's winter in Kew.
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It's so cold and the sun's rays are so feeble
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that plants can't grow.
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And leaves in winter can be a liability.
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A fully-canopied tree
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can be uprooted by the winter gales.
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And in any case, the flimsy leaves of oaks and beeches
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will be destroyed by the frosts.
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So many such trees stand naked
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and inactive throughout the winter.
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But eventually,
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the sun begins to rise higher and higher in the sky.
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The day is getting warmer
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and spring arrives.
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Light and heat sensitive molecules inside plant cells
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are the triggers of germination and flowering.
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Timing is critical.
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Bloom too early and frost can kill a plant.
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Too late and they can be swamped by the growth of its rivals.
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The first scent flowers are bulbs.
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The beds in front of Kew's Palm House
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are transformed as they burst into color.
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Then, trees join the race.
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Cherries
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and magnolias.
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Their flowers last just long enough to attract pollinators
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and then they will fall.
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Meanwhile in the woods,
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bluebells begin to appear.
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They must grow fast
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if they are to collect their share of the spring sunshine
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before the canopy develops over head
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and cuts it off from them.
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But in some parts of the world,
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spring and summer may last only a few weeks.
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And the plants that live there
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have to complete their annual activities very swiftly.
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Kew makes special arrangements for them.
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This is the garden's newest glass house.
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It's the Alpine House.
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Inside grow plants from the mountains
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where spring and summer not only brief
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but bitter.
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This house has been built to replicate alpine conditions
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and it does it with this strange shape.
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Deep below ground,
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there is a labyrinth of concrete passages
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where the air is very cold.
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And as the temperature up here warms,
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so that cold air is drawn up through vents
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and flows over the plants on ground level.
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Then it warms still further,
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rises and escapes through vents of the top.
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And when the sun is really strong,
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it's got a further trick up its sleeve.
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It's usually the melting snow
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that stimulates alpine plants to bloom.
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But here, technology creates such continuous conditions
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that alpines flower without it.
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The alpine Allium,
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Roscoea, a Himalayan plant
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which is closely related to ginger,
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and sempervivum,
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a plant so hardy,
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it can root in tiny cracks between the rocks.
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Mountain plants, it's true, are nearly all tiny,
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but they have the beauty and fascination of jewels.
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However, flowers did not evolve to please our eyes.
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Their function is to please insects.
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Nobody can be exactly sure how insects view the world,
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but it's certainly rather different from the way we do.
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We can see a part of the spectrum from red,
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which is a long wavelength light,
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through orange, yellow,
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and green and blue to violet,
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which is short wavelength light.
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But insects can see even shorter wavelength still.
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They can see ultraviolet.
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And we can use special cameras
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to reveal just what information
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that sensitivity to ultraviolet light reveals.
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We can move from how we see the world
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to how insects might see it.
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By looking at flowers in this way,
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we can begin to understand their true purpose.
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This flower,
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to our eyes, it seems to have uniformly plain pedals.
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But the insect looking at it in ultraviolet,
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each pedal has a white tip,
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so there is a circle of white
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drawing attention to the bull's eye,
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which is there for the insect can find pollen.
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This flower which, to our eyes, appears to be in plain blue.
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The ultraviolet light has white pedals
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with lines running down it all the way around
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pointing towards the center.
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And this is the common fox glove
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with, to our eyes,
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nothing more than a few random markings on its throat.
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But to an insect, there are more.
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These white lines probably act as landing lights
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which guide it to the nectar.
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Most important structures are often the most vivid colored.
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The nectaries glow brightly.
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As does the pollen.
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The four-o'clock flower blooms at dusk
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and has fluorescent pollen
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that attracts night flying moths.
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This sensitivity to ultraviolet
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is just one way in which plants communicate with insects.
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Plant don't rely solely on color
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to attract their insect pollinators.
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They also produce smells.
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In fact, as I stand here,
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I'm surrounded by a swirling vortex
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of perfumes of many kinds.
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Unhappily,
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the human nostrils can only detect
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about five percent of them.
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Insects do very much better.
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We can imagine microscopic droplets of these volatile oils
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suspended in the air.
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Many insects have antennae
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that are extraordinary sensitive to them.
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Some can detect concentration of
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just a few parts per billion.
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As a consequence,
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insects can smell a flower from as much as a mile away.
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But messages can also travel in another direction.
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Some insects can communicate with plants.
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They do it with sound.
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Some flowers are extremely fussy
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about their pollinators.
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This is Gustavia
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from the Amazon rainforests.
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Here are its flower buds.
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Each one will only open for a few hours
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and in that time, it has to be visited
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by a particular kind of bee,
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the buzzes with a particular musical note.
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Of course, there aren't bees like that
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flying around here in London.
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We have ways of deceiving Gustavia
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with a tuning fork.
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All we have to do now
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is to wait for the flowers to open.
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A tuning fork that resonates
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at exactly the pitch of Gustavia's bee
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will cause the stamens to vibrate.
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The motion releases the pollen
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that would otherwise remain locked fast in the flower.
275
00:21:58,340 --> 00:21:59,611
The bee gains
276
00:21:59,612 --> 00:22:03,715
because it has exclusive access to a nutritious food source
277
00:22:03,749 --> 00:22:05,652
and therefore favors it.
278
00:22:08,755 --> 00:22:10,527
And the plant has a courier
279
00:22:10,630 --> 00:22:14,664
who is almost certain to deliver the pollen to the right address.
280
00:22:18,306 --> 00:22:21,102
We've highlighted Gustavia's pollen cloud
281
00:22:21,215 --> 00:22:22,943
because the grains are so fine,
282
00:22:22,954 --> 00:22:25,602
they are impossible to see with the naked eye.
283
00:22:30,346 --> 00:22:34,040
But there is a way to examine even the tiniest pollen grain
284
00:22:34,142 --> 00:22:36,881
with an electron microscope.
285
00:22:47,875 --> 00:22:49,909
The colors are artificial,
286
00:22:50,103 --> 00:22:52,898
but these pollen grains are minute.
287
00:22:54,325 --> 00:22:55,643
This is cedar pollen
288
00:22:55,665 --> 00:22:59,165
magnified 7,000 times.
289
00:23:03,109 --> 00:23:07,878
Each grain contains a tiny bundle of the particular DNA
290
00:23:07,879 --> 00:23:09,674
that will fertilize the flower
291
00:23:09,711 --> 00:23:13,383
produced by another individual of the same species.
292
00:23:16,588 --> 00:23:19,063
But it has to get to such a flower
293
00:23:21,614 --> 00:23:25,447
Some plants use animals as couriers.
294
00:23:27,451 --> 00:23:30,079
This mountain ebony pollen is sticky
295
00:23:30,208 --> 00:23:32,899
and clings to the fur of bats.
296
00:23:34,323 --> 00:23:37,712
Eelgrass pollen carries a bundle of pheromones
297
00:23:37,724 --> 00:23:39,827
that will suspend the grains in water
298
00:23:39,853 --> 00:23:43,801
at just the depth at which the plant's flowers bloom.
299
00:23:53,703 --> 00:23:57,780
The wind-disperse pollen grains produced by pines
300
00:23:57,895 --> 00:24:02,152
drift through the air with the help of tiny air sacks.
301
00:24:05,818 --> 00:24:08,117
Looking at the grains through a microscope
302
00:24:08,168 --> 00:24:12,398
reveals how astonishingly complex their shapes can be.
303
00:24:13,297 --> 00:24:17,694
Each is unique to one particular species of plant.
304
00:24:19,156 --> 00:24:22,352
Only grains of that shape and right DNA
305
00:24:22,467 --> 00:24:26,249
will fertilize the flowers of the species that produce it.
306
00:24:32,523 --> 00:24:35,395
A pollen grain, when it arrives on such a flower,
307
00:24:35,497 --> 00:24:38,728
doesn't swim like the sperm of an animal.
308
00:24:39,869 --> 00:24:42,625
Instead, as the illustration shows,
309
00:24:42,728 --> 00:24:44,484
it produces a tube
310
00:24:44,497 --> 00:24:46,962
which grows down into the ovary
311
00:24:47,027 --> 00:24:49,373
at the very center of the flower.
312
00:24:57,232 --> 00:24:59,031
With each new season,
313
00:24:59,082 --> 00:25:02,146
new worlds reveal themselves.
314
00:25:04,941 --> 00:25:06,185
In late spring,
315
00:25:06,198 --> 00:25:08,954
the longer days and stronger sunlight
316
00:25:08,967 --> 00:25:11,928
cue the emergence of leaves.
317
00:25:27,475 --> 00:25:30,539
The gardens are transformed.
318
00:25:41,142 --> 00:25:43,657
Each plant arranges its leaves,
319
00:25:43,684 --> 00:25:47,171
so that there is the minimum of overlap between them.
320
00:25:57,586 --> 00:26:00,586
They grow to fill all the available space
321
00:26:00,624 --> 00:26:02,457
ensuring that every ray of light
322
00:26:02,483 --> 00:26:05,727
is harnessed by the green chlorophyll inside them.
323
00:26:18,441 --> 00:26:21,191
Up here in this walkway through the treetops,
324
00:26:21,308 --> 00:26:24,274
you can see the process as it happens.
325
00:26:24,530 --> 00:26:26,430
In just a few weeks,
326
00:26:26,546 --> 00:26:29,196
the trees close themselves in green.
327
00:26:29,546 --> 00:26:33,396
The amount they produce of leaves and shoots is extraordinary.
328
00:26:33,496 --> 00:26:34,863
In just one acre,
329
00:26:34,963 --> 00:26:37,730
it can weigh four tons.
330
00:26:42,585 --> 00:26:44,934
During the long warm days of summer,
331
00:26:44,935 --> 00:26:49,485
leaves of all shapes and sizes grow in great abundance.
332
00:26:50,224 --> 00:26:53,657
And it's not just plants that depend on them.
333
00:26:57,974 --> 00:27:01,207
The rich foliates provide hidden habitats
334
00:27:01,257 --> 00:27:05,074
for whole communities of tiny insect herbivores
335
00:27:05,829 --> 00:27:07,679
and their predators.
336
00:27:23,134 --> 00:27:26,318
For many, leaves are food.
337
00:27:30,818 --> 00:27:32,634
Blackflies get what they need
338
00:27:32,751 --> 00:27:35,173
by stabbing their needle-like mouth parts
339
00:27:35,190 --> 00:27:37,840
into the veins of leaves and stems
340
00:27:37,923 --> 00:27:39,956
and extracting the sap.
341
00:27:40,706 --> 00:27:43,459
They don't even need to suck.
342
00:27:43,673 --> 00:27:45,790
The pressure inside the plant
343
00:27:45,823 --> 00:27:49,178
is enough to squirt the sap into their stomachs.
344
00:27:52,512 --> 00:27:56,217
Mealybugs are also sap drinkers.
345
00:27:56,428 --> 00:27:59,644
They produce a waxy powder from their skin,
346
00:27:59,678 --> 00:28:01,650
which most predators dislike,
347
00:28:01,817 --> 00:28:05,284
so that they are able to drink unmolested out in the open.
348
00:28:09,817 --> 00:28:12,534
Snail rip through the vegetation
349
00:28:12,550 --> 00:28:16,856
rasping off mouthfuls with a long file-like tongue.
350
00:28:23,072 --> 00:28:25,511
A single snail can consume
351
00:28:25,528 --> 00:28:28,377
a fifth of the weight of its body, shell and all,
352
00:28:28,478 --> 00:28:30,061
in a single day.
353
00:28:38,644 --> 00:28:41,571
So insects and other small creatures,
354
00:28:41,683 --> 00:28:43,783
some helpful, some harmful,
355
00:28:43,933 --> 00:28:46,066
flourish through the summer.
356
00:28:48,733 --> 00:28:52,366
This is the time when most of them reproduce.
357
00:28:52,983 --> 00:28:56,538
And they do so with staggering speed.
358
00:28:58,838 --> 00:29:02,705
Female aphids mate and lay eggs like other insects,
359
00:29:02,738 --> 00:29:04,889
but they also produce clones,
360
00:29:05,155 --> 00:29:09,072
babies that hatch from unfertilized eggs.
361
00:29:10,327 --> 00:29:12,126
And the clones themselves,
362
00:29:12,127 --> 00:29:14,527
even before they leave the female's body,
363
00:29:14,577 --> 00:29:18,927
are already pregnant with other clones.
364
00:29:24,216 --> 00:29:26,616
Such telescope generations
365
00:29:26,632 --> 00:29:29,316
enable aphids to infest a whole plant
366
00:29:29,399 --> 00:29:31,449
in a matter of hours.
367
00:29:35,754 --> 00:29:39,238
But aphids are themselves food for others
368
00:29:39,438 --> 00:29:43,438
and assemblies like these don't go unnoticed
369
00:29:44,971 --> 00:29:47,471
by other insects.
370
00:29:49,826 --> 00:29:51,593
Among the most ferocious,
371
00:29:51,693 --> 00:29:54,576
are the many kinds of ladybird
372
00:29:55,260 --> 00:29:56,710
and their lavae.
373
00:29:58,860 --> 00:30:02,259
This is the young of a ladybird called Cryptolaeumus
374
00:30:02,410 --> 00:30:04,276
and it eats virtually nothing
375
00:30:04,382 --> 00:30:07,203
but Mealybugs and aphids
376
00:30:08,198 --> 00:30:11,298
when young and as an adult.
377
00:30:17,237 --> 00:30:20,837
This is a fasting moving young of a hoverfly.
378
00:30:33,976 --> 00:30:37,642
This larva of a lacewing is totally blind,
379
00:30:37,726 --> 00:30:40,076
but it doesn't need to see.
380
00:30:41,992 --> 00:30:44,481
It has an acute sense of smell
381
00:30:44,614 --> 00:30:49,763
and is specially sensitive to the pheromones produced by aphids.
382
00:30:50,014 --> 00:30:51,448
It attacks its prey
383
00:30:51,464 --> 00:30:54,990
by impaling them on a large hook in its mouth
384
00:30:55,164 --> 00:30:57,614
and then sucking them dry.
385
00:31:00,603 --> 00:31:03,822
And it has an unquenchable appetite.
386
00:31:05,920 --> 00:31:09,903
It could eat up to 600 aphids before it's adult.
387
00:31:13,525 --> 00:31:16,958
Most predators aren't fussy about the plants they live on
388
00:31:17,092 --> 00:31:19,442
as long as there is prey to hunt.
389
00:31:22,475 --> 00:31:23,733
But one predator
390
00:31:23,824 --> 00:31:26,608
has formed a special partnership with a plant
391
00:31:26,714 --> 00:31:30,014
that looks rather like the insect-eating sundew.
392
00:31:32,230 --> 00:31:33,180
This plant,
393
00:31:33,664 --> 00:31:35,864
which is called Roridula,
394
00:31:36,314 --> 00:31:38,197
also catches insects
395
00:31:38,397 --> 00:31:42,602
which get stuck to these sticky hairs on its leaves.
396
00:31:51,469 --> 00:31:52,741
Oddly enough,
397
00:31:52,791 --> 00:31:56,974
Roridula can't digest insect bodies.
398
00:31:57,791 --> 00:31:59,974
Instead, it gets help
399
00:32:00,008 --> 00:32:03,708
from one particular kind of insect called capsid bug,
400
00:32:04,324 --> 00:32:07,691
which lives nowhere else but on Roridula.
401
00:32:10,096 --> 00:32:12,546
And the capsid bug runs around
402
00:32:12,680 --> 00:32:14,896
on these leaves without getting stuck
403
00:32:16,063 --> 00:32:20,968
because its body is coated with a non-stick substance.
404
00:32:23,885 --> 00:32:25,202
And the capsid bug
405
00:32:25,402 --> 00:32:28,735
goes and feeds on the bodies of the insects
406
00:32:28,785 --> 00:32:31,018
the Roridula has caught.
407
00:32:33,168 --> 00:32:36,607
And when an insect lands and is caught,
408
00:32:36,674 --> 00:32:38,640
the capsid bug runs across,
409
00:32:38,790 --> 00:32:42,757
sticks its mouth part into the insect body
410
00:32:42,790 --> 00:32:44,757
and sucks it dry.
411
00:33:13,715 --> 00:33:16,606
Then it produces droppings which fall to the ground
412
00:33:16,956 --> 00:33:20,390
and those can feed Roricula.
413
00:33:28,040 --> 00:33:30,078
The carefully controlled conditions
414
00:33:30,091 --> 00:33:32,373
inside Kew's glass houses
415
00:33:32,476 --> 00:33:34,604
certainly suit plants.
416
00:33:35,822 --> 00:33:36,809
But equally,
417
00:33:37,053 --> 00:33:38,899
they suit insects.
418
00:33:41,775 --> 00:33:45,454
So something has to be done to keep pests in check.
419
00:33:48,428 --> 00:33:52,377
One way is to introduce predators -
420
00:33:54,183 --> 00:33:57,183
Asian water dragons.
421
00:34:01,791 --> 00:34:04,779
They exists on a diet of mealworms
422
00:34:04,945 --> 00:34:06,740
and cockroaches.
423
00:34:17,295 --> 00:34:20,158
They quickly learn that daily hosing down
424
00:34:20,180 --> 00:34:22,555
will drive the cockroaches out of the cracks
425
00:34:22,556 --> 00:34:24,658
where they hide during the day.
426
00:34:57,718 --> 00:35:01,230
There are also more subtle ways of controlling pests
427
00:35:01,282 --> 00:35:03,705
that visitors seldom notice.
428
00:35:04,683 --> 00:35:08,145
These cards have been coated with microscopic eggs
429
00:35:08,530 --> 00:35:09,748
of a wasp.
430
00:35:17,495 --> 00:35:18,648
When they hatch,
431
00:35:18,649 --> 00:35:22,380
the young wasps go off and search for their favorite prey -
432
00:35:23,688 --> 00:35:24,944
aphids.
433
00:35:34,551 --> 00:35:37,884
This one has discovered aphid pupae.
434
00:35:39,153 --> 00:35:41,050
It selects its target
435
00:35:41,089 --> 00:35:44,063
and injects it with an egg of its own.
436
00:35:45,849 --> 00:35:48,388
When the larva hatches within its host,
437
00:35:48,426 --> 00:35:50,632
it will eat it alive,
438
00:35:51,426 --> 00:35:53,606
just as others have done before it.
439
00:35:57,183 --> 00:36:00,633
These are the dried out husks of victims -
440
00:36:03,636 --> 00:36:05,340
aphid mummies.
441
00:36:17,691 --> 00:36:21,768
Kew is starting its next great seasonal transformation -
442
00:36:23,140 --> 00:36:24,217
autumn.
443
00:36:33,298 --> 00:36:34,823
Plants growing outside
444
00:36:34,836 --> 00:36:37,144
without the protection of the glass houses
445
00:36:37,221 --> 00:36:40,349
must get ready for the bad conditions that are coming.
446
00:36:41,917 --> 00:36:44,737
Trees prepare to lose their leaves.
447
00:36:45,391 --> 00:36:47,468
The green chlorophyll inside them
448
00:36:47,481 --> 00:36:51,109
begins to break down to be reabsorbed.
449
00:36:52,075 --> 00:36:56,100
The bright colors are byproducts of the process.
450
00:37:07,848 --> 00:37:09,552
As the leaves fall,
451
00:37:09,605 --> 00:37:12,117
a new world reveals itself
452
00:37:12,246 --> 00:37:14,233
from beneath the soil.
453
00:37:19,861 --> 00:37:21,194
Fungi.
454
00:37:31,647 --> 00:37:34,262
Fungi can't photosynthesize
455
00:37:34,288 --> 00:37:37,356
because, unlike plants, they have no chlorophyll.
456
00:37:39,228 --> 00:37:42,601
In fact, they are more closely related to animals
457
00:37:42,664 --> 00:37:44,304
and are made of chitin,
458
00:37:44,420 --> 00:37:48,382
the material insects use for their skeletons.
459
00:37:54,107 --> 00:37:57,186
These are the fruiting bodies of a fungus.
460
00:37:57,527 --> 00:38:00,799
Their function is to produce dust-like spores
461
00:38:00,800 --> 00:38:03,652
which are then blown away through the woodland
462
00:38:03,897 --> 00:38:05,522
to grow elsewhere.
463
00:38:06,261 --> 00:38:09,692
But these are only a tiny part of the fungus.
464
00:38:09,954 --> 00:38:12,761
Most of the body of the fungus
465
00:38:12,908 --> 00:38:14,113
is beneath the ground,
466
00:38:14,136 --> 00:38:16,373
a tangle of tiny treads
467
00:38:16,374 --> 00:38:19,903
which extend for hundreds of yards.
468
00:38:20,005 --> 00:38:21,312
through the forest.
469
00:38:21,812 --> 00:38:23,630
And we are now begin to realize
470
00:38:23,892 --> 00:38:26,608
that those threads are essential
471
00:38:26,983 --> 00:38:28,653
to the growth and health
472
00:38:28,869 --> 00:38:30,812
of many of the woodland plants.
473
00:38:43,136 --> 00:38:47,302
The length of these threads is almost unbelievable.
474
00:38:52,370 --> 00:38:54,301
One specimen in America
475
00:38:54,336 --> 00:38:58,472
was found to extend across nearly four square miles.
476
00:38:58,774 --> 00:39:01,376
That's an area 16 times bigger
477
00:39:01,455 --> 00:39:03,490
than Kew Gardens itself.
478
00:39:05,330 --> 00:39:06,671
Technically speaking,
479
00:39:06,717 --> 00:39:10,501
it's the largest known living organism on the plant.
480
00:39:22,859 --> 00:39:24,649
Most fungi make a living
481
00:39:24,661 --> 00:39:27,929
by feeding on the dead tissues of other organisms,
482
00:39:28,070 --> 00:39:30,104
both plant and animal.
483
00:39:47,758 --> 00:39:49,974
They produce powerful chemicals
484
00:39:49,985 --> 00:39:51,718
that enable them to break down
485
00:39:51,730 --> 00:39:54,912
about 90 percent of all organic matter,
486
00:39:55,934 --> 00:39:58,287
including leaves and wood.
487
00:40:01,480 --> 00:40:02,616
In doing this,
488
00:40:02,673 --> 00:40:05,127
they release the nutrients to the soil
489
00:40:05,128 --> 00:40:08,565
that plants need to fuel their new growth in the spring.
490
00:40:09,690 --> 00:40:13,013
So fungi are essential links
491
00:40:13,111 --> 00:40:15,202
in the cycle of life.
492
00:40:19,156 --> 00:40:22,560
But some fungi establish partnerships with plants
493
00:40:22,583 --> 00:40:24,787
while the plants are still alive.
494
00:40:26,015 --> 00:40:28,481
And they are just as important.
495
00:40:31,083 --> 00:40:34,026
This is the Lucombe Oak.
496
00:40:34,453 --> 00:40:38,521
It germinated from an acorn in the year 1762
497
00:40:38,691 --> 00:40:41,384
and is one of the oldest plants in Kew.
498
00:40:41,987 --> 00:40:45,157
It's roots are covered with a fungus.
499
00:40:45,617 --> 00:40:47,134
But that's not a friction.
500
00:40:47,595 --> 00:40:51,322
That's the reason why this tree was able to live for so long
501
00:40:52,118 --> 00:40:54,606
because the fungus can do something
502
00:40:54,629 --> 00:40:56,061
that the oak tree can't.
503
00:40:56,402 --> 00:40:59,561
It can extract nitrogen directly from the soil
504
00:41:00,038 --> 00:41:02,845
and then the oak tree collect it from the fungus.
505
00:41:03,283 --> 00:41:06,192
And in return, the fungus takes sugars
506
00:41:06,419 --> 00:41:08,783
from the sap in the roots of the oak tree.
507
00:41:09,499 --> 00:41:12,601
So it's a mutually convenient arrangement,
508
00:41:12,613 --> 00:41:14,976
an symbiotic relationship.
509
00:41:15,460 --> 00:41:16,993
In fact, we now know
510
00:41:16,994 --> 00:41:21,653
that around 90 percent of the species of plants on the earth
511
00:41:22,130 --> 00:41:24,789
depend upon fungi one way or another.
512
00:41:26,829 --> 00:41:28,862
Kew cares for fungi
513
00:41:28,920 --> 00:41:31,057
just as it does for plants.
514
00:41:31,682 --> 00:41:35,784
A special underground world has been created for them.
515
00:41:40,767 --> 00:41:43,789
Here, thousands of different species
516
00:41:43,938 --> 00:41:46,019
are preserved in boxes.
517
00:41:49,017 --> 00:41:50,642
This is the fungarium.
518
00:41:51,324 --> 00:41:54,869
There are more specimens of fungi here
519
00:41:54,972 --> 00:41:56,868
than anywhere else in the world,
520
00:41:56,869 --> 00:41:59,319
one and a quarter million of them.
521
00:41:59,796 --> 00:42:01,056
And such has come
522
00:42:01,091 --> 00:42:04,001
from all over the world, here to Kew,
523
00:42:04,057 --> 00:42:05,796
in order to study them.
524
00:42:07,785 --> 00:42:11,086
The fungarium contains specimens that Kew has collected
525
00:42:11,098 --> 00:42:14,257
through out the course of its 400-year history.
526
00:42:17,154 --> 00:42:19,688
They are stored for their potential value
527
00:42:19,859 --> 00:42:21,586
in science and medicine.
528
00:42:23,336 --> 00:42:26,513
Perhaps the most famous is this one.
529
00:42:27,308 --> 00:42:29,638
This is Penicillium,
530
00:42:29,695 --> 00:42:33,206
a mold from which we get penicillin.
531
00:42:34,229 --> 00:42:37,592
Here's another which is able to digest oil.
532
00:42:37,894 --> 00:42:39,689
And scientists are working to see
533
00:42:39,712 --> 00:42:43,098
whether it could be used for in cleaning up oil spills.
534
00:42:44,132 --> 00:42:46,678
But fungi can also be very sinister.
535
00:42:48,394 --> 00:42:51,235
This caterpillar has a fungus
536
00:42:51,246 --> 00:42:53,184
growing from its head.
537
00:42:54,070 --> 00:42:56,798
It's a species of Cordyceps,
538
00:42:56,957 --> 00:42:58,411
a tropical fungus
539
00:42:58,445 --> 00:43:01,525
that has developed a gruesome power.
540
00:43:02,968 --> 00:43:06,139
They can infect the brain of an animal.
541
00:43:06,554 --> 00:43:08,735
One infects ants
542
00:43:08,736 --> 00:43:12,361
and causes ants to climb up a grass stem,
543
00:43:12,963 --> 00:43:15,031
tamp its jaws on the top,
544
00:43:15,304 --> 00:43:17,565
and there, high up on the plant,
545
00:43:17,656 --> 00:43:19,508
the fungus kills it.
546
00:43:26,071 --> 00:43:29,889
A long fruiting body then bursts out of the ant's brain.
547
00:43:33,611 --> 00:43:35,395
This elaborate behavior
548
00:43:35,430 --> 00:43:38,555
enables the fungus to rise high above the ground
549
00:43:38,600 --> 00:43:41,497
and shower its spores over great distances
550
00:43:41,498 --> 00:43:44,589
and so reach new victims.
551
00:43:49,822 --> 00:43:52,879
The world of plants is still full of secrets
552
00:43:52,890 --> 00:43:55,390
even though we have so many different ways
553
00:43:55,402 --> 00:43:57,788
of investigating their lives.
554
00:44:03,624 --> 00:44:05,838
One of the most famous species
555
00:44:05,839 --> 00:44:09,430
has been something of a mystery until only a few years ago.
556
00:44:11,271 --> 00:44:13,044
It may look like a tree,
557
00:44:13,198 --> 00:44:17,709
but in reality, this is just a single giant leaf.
558
00:44:19,880 --> 00:44:22,425
It's called the titian arum
559
00:44:22,823 --> 00:44:25,380
and it's a record breaker.
560
00:44:27,818 --> 00:44:30,113
But not because of what you see now.
561
00:44:30,624 --> 00:44:31,873
In a week or so,
562
00:44:32,011 --> 00:44:35,306
that green stem and the leaflets that go on top
563
00:44:35,624 --> 00:44:37,704
will die, and rot,
564
00:44:37,852 --> 00:44:39,011
and disappear.
565
00:44:39,630 --> 00:44:41,494
But beneath the surface of the soil,
566
00:44:41,505 --> 00:44:44,153
there is a gigantic tuber,
567
00:44:44,449 --> 00:44:45,653
and it's from that
568
00:44:45,812 --> 00:44:48,324
that the record breaker will emerge.
569
00:44:55,773 --> 00:44:57,795
This extraordinary event
570
00:44:57,796 --> 00:45:01,705
occurs just once every seven years.
571
00:45:02,875 --> 00:45:05,591
It will take two months to complete.
572
00:45:28,524 --> 00:45:31,842
But this new growth is neither a trunk,
573
00:45:31,853 --> 00:45:33,581
nor a leaf.
574
00:45:40,746 --> 00:45:44,675
It's the bud of the biggest flower in the world.
575
00:45:57,763 --> 00:46:00,468
As it grows day after day,
576
00:46:00,627 --> 00:46:03,541
a huge spire, the spadix,
577
00:46:03,678 --> 00:46:07,406
rises from the center of the developing flower.
578
00:46:12,735 --> 00:46:16,803
And then one evening as darkness falls over the forest,
579
00:46:17,150 --> 00:46:20,184
the giant flower opens.
580
00:46:36,372 --> 00:46:41,697
This, surely, is one of the most astonishing of blooms.
581
00:46:48,958 --> 00:46:52,685
I first saw one of these amazing flowers
582
00:46:52,788 --> 00:46:56,901
growing in the wild in the tropical rainforest of Sumatra.
583
00:46:57,163 --> 00:46:59,373
But why are they so big?
584
00:47:00,089 --> 00:47:03,239
Well, the function of the flower, like all flowers,
585
00:47:03,632 --> 00:47:05,452
is to attract pollinator.
586
00:47:05,796 --> 00:47:09,928
And this plant gives off the smell of rotting flesh.
587
00:47:10,796 --> 00:47:13,141
But it does something else.
588
00:47:13,617 --> 00:47:17,748
Something you can see with a heat sensitive camera.
589
00:47:22,502 --> 00:47:24,599
This remarkable device
590
00:47:24,650 --> 00:47:27,404
reveals something astonishing.
591
00:47:35,076 --> 00:47:37,634
The white areas at the base of the spire
592
00:47:37,667 --> 00:47:39,404
are significantly hotter
593
00:47:39,454 --> 00:47:41,569
than the surrounding plant.
594
00:47:43,421 --> 00:47:45,126
It's heating up.
595
00:47:47,831 --> 00:47:49,060
At its hottest,
596
00:47:49,061 --> 00:47:52,667
the spire can reach 37 degrees centigrade,
597
00:47:52,700 --> 00:47:56,537
the same temperature as the body of a mammal.
598
00:48:01,816 --> 00:48:04,733
And as it warms, something else happens
599
00:48:04,766 --> 00:48:07,737
inside the flower at the base of the spire.
600
00:48:10,915 --> 00:48:16,046
Hundreds of smaller structures begin to produce stringy pollen.
601
00:48:27,833 --> 00:48:30,522
The titan arum is readying itself
602
00:48:30,571 --> 00:48:34,243
for the arrival of pollinating insects.
603
00:48:36,982 --> 00:48:40,932
Tiny sweat-bees and probably carrion beetles as well
604
00:48:41,064 --> 00:48:46,441
are attracted by a combination of the powerful smell and the heat.
605
00:48:48,425 --> 00:48:52,310
Other flowers that smell of carrion also produce heat.
606
00:48:52,474 --> 00:48:54,736
So it seems that what is happening
607
00:48:54,851 --> 00:48:57,112
is that they are mimicking the warmth
608
00:48:57,113 --> 00:48:59,572
of the body of recently dead animal.
609
00:49:00,556 --> 00:49:02,736
But the hot air
610
00:49:02,819 --> 00:49:05,819
produced in pulses from the top narrow spire
611
00:49:06,016 --> 00:49:07,819
must have a different function.
612
00:49:11,294 --> 00:49:12,353
At night,
613
00:49:12,447 --> 00:49:15,755
a layer of cold air, still air,
614
00:49:15,768 --> 00:49:19,918
forms between the forest canopy and the forest floor.
615
00:49:20,361 --> 00:49:23,197
But the spire of the titan arum
616
00:49:23,249 --> 00:49:25,738
producing the pulses of warm air
617
00:49:25,947 --> 00:49:27,882
pierces that barrier
618
00:49:27,883 --> 00:49:30,000
so that the smell of the titan arum
619
00:49:30,093 --> 00:49:32,312
spreads out of the top of the canopy
620
00:49:32,443 --> 00:49:33,913
far and wide.
621
00:49:33,984 --> 00:49:36,099
so attracting insects,
622
00:49:36,234 --> 00:49:39,476
pollinating insects, from a long way away.
623
00:49:41,956 --> 00:49:44,224
If we could imagine such a spectacle,
624
00:49:44,250 --> 00:49:47,045
it would look something like smoke from a chimney
625
00:49:47,161 --> 00:49:50,032
discharging heat into the night sky.
626
00:49:59,960 --> 00:50:03,639
It remains in bloom for just two days.
627
00:50:08,625 --> 00:50:10,729
And then, it closes.
628
00:50:34,160 --> 00:50:35,968
Science has given us a glimpse
629
00:50:35,981 --> 00:50:38,288
into a hitherto unseen world.
630
00:50:38,574 --> 00:50:41,869
However, our journey of discovery has only just started.
631
00:50:42,408 --> 00:50:44,459
As technology advances,
632
00:50:44,562 --> 00:50:46,433
so will our understanding
633
00:50:46,497 --> 00:50:49,318
of the hidden world of plants.
634
00:50:54,578 --> 00:50:57,437
The final frontier of plant discovery
635
00:50:57,553 --> 00:51:00,181
is in the dry zone.
636
00:51:05,284 --> 00:51:06,312
In deserts,
637
00:51:06,339 --> 00:51:09,429
plants use an extraordinary adaptations
638
00:51:09,441 --> 00:51:11,185
in order to survive
639
00:51:12,262 --> 00:51:14,749
by day and by night.
640
00:51:23,817 --> 00:51:25,933
And as we will discover,
641
00:51:26,048 --> 00:51:30,215
new research into plants' astonishing time capsules of life -
642
00:51:30,304 --> 00:51:31,625
their seeds -
643
00:51:31,753 --> 00:51:33,702
could ensure that no plant
644
00:51:33,732 --> 00:51:36,539
need ever become extinct again.
47472
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