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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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00:21:46,493 --> 00:21:48,340
The motion releases the pollen
275
00:21:48,555 --> 00:21:51,817
that would otherwise remain locked fast in the flower.
276
00:21:56,340 --> 00:21:57,611
The bee gains
277
00:21:57,612 --> 00:22:01,715
because it has exclusive access to a nutritious food source
278
00:22:01,749 --> 00:22:03,652
and therefore favors it.
279
00:22:06,755 --> 00:22:08,527
And the plant has a courier
280
00:22:08,630 --> 00:22:12,664
who is almost certain to deliver the pollen to the right address.
281
00:22:16,306 --> 00:22:19,102
We've highlighted Gustavia's pollen cloud
282
00:22:19,215 --> 00:22:20,943
because the grains are so fine,
283
00:22:20,954 --> 00:22:23,602
they are impossible to see with the naked eye.
284
00:22:28,346 --> 00:22:32,040
But there is a way to examine even the tiniest pollen grain
285
00:22:32,142 --> 00:22:34,881
with an electron microscope.
286
00:22:45,875 --> 00:22:47,909
The colors are artificial,
287
00:22:48,103 --> 00:22:50,898
but these pollen grains are minute.
288
00:22:52,325 --> 00:22:53,643
This is cedar pollen
289
00:22:53,665 --> 00:22:57,165
magnified 7,000 times.
290
00:23:01,109 --> 00:23:05,878
Each grain contains a tiny bundle of the particular DNA
291
00:23:05,879 --> 00:23:07,674
that will fertilize the flower
292
00:23:07,711 --> 00:23:11,383
produced by another individual of the same species.
293
00:23:14,588 --> 00:23:17,063
But it has to get to such a flower
294
00:23:19,614 --> 00:23:23,447
Some plants use animals as couriers.
295
00:23:25,451 --> 00:23:28,079
This mountain ebony pollen is sticky
296
00:23:28,208 --> 00:23:30,899
and clings to the fur of bats.
297
00:23:32,323 --> 00:23:35,712
Eelgrass pollen carries a bundle of pheromones
298
00:23:35,724 --> 00:23:37,827
that will suspend the grains in water
299
00:23:37,853 --> 00:23:41,801
at just the depth at which the plant's flowers bloom.
300
00:23:51,703 --> 00:23:55,780
The wind-disperse pollen grains produced by pines
301
00:23:55,895 --> 00:24:00,152
drift through the air with the help of tiny air sacks.
302
00:24:03,818 --> 00:24:06,117
Looking at the grains through a microscope
303
00:24:06,168 --> 00:24:10,398
reveals how astonishingly complex their shapes can be.
304
00:24:11,297 --> 00:24:15,694
Each is unique to one particular species of plant.
305
00:24:17,156 --> 00:24:20,352
Only grains of that shape and right DNA
306
00:24:20,467 --> 00:24:24,249
will fertilize the flowers of the species that produce it.
307
00:24:30,523 --> 00:24:33,395
A pollen grain, when it arrives on such a flower,
308
00:24:33,497 --> 00:24:36,728
doesn't swim like the sperm of an animal.
309
00:24:37,869 --> 00:24:40,625
Instead, as the illustration shows,
310
00:24:40,728 --> 00:24:42,484
it produces a tube
311
00:24:42,497 --> 00:24:44,962
which grows down into the ovary
312
00:24:45,027 --> 00:24:47,373
at the very center of the flower.
313
00:24:55,232 --> 00:24:57,031
With each new season,
314
00:24:57,082 --> 00:25:00,146
new worlds reveal themselves.
315
00:25:02,941 --> 00:25:04,185
In late spring,
316
00:25:04,198 --> 00:25:06,954
the longer days and stronger sunlight
317
00:25:06,967 --> 00:25:09,928
cue the emergence of leaves.
318
00:25:25,475 --> 00:25:28,539
The gardens are transformed.
319
00:25:39,142 --> 00:25:41,657
Each plant arranges its leaves,
320
00:25:41,684 --> 00:25:45,171
so that there is the minimum of overlap between them.
321
00:25:55,586 --> 00:25:58,586
They grow to fill all the available space
322
00:25:58,624 --> 00:26:00,457
ensuring that every ray of light
323
00:26:00,483 --> 00:26:03,727
is harnessed by the green chlorophyll inside them.
324
00:26:16,441 --> 00:26:19,191
Up here in this walkway through the treetops,
325
00:26:19,308 --> 00:26:22,274
you can see the process as it happens.
326
00:26:22,530 --> 00:26:24,430
In just a few weeks,
327
00:26:24,546 --> 00:26:27,196
the trees close themselves in green.
328
00:26:27,546 --> 00:26:31,396
The amount they produce of leaves and shoots is extraordinary.
329
00:26:31,496 --> 00:26:32,863
In just one acre,
330
00:26:32,963 --> 00:26:35,730
it can weigh four tons.
331
00:26:40,585 --> 00:26:42,934
During the long warm days of summer,
332
00:26:42,935 --> 00:26:47,485
leaves of all shapes and sizes grow in great abundance.
333
00:26:48,224 --> 00:26:51,657
And it's not just plants that depend on them.
334
00:26:55,974 --> 00:26:59,207
The rich foliates provide hidden habitats
335
00:26:59,257 --> 00:27:03,074
for whole communities of tiny insect herbivores
336
00:27:03,829 --> 00:27:05,679
and their predators.
337
00:27:21,134 --> 00:27:24,318
For many, leaves are food.
338
00:27:28,818 --> 00:27:30,634
Blackflies get what they need
339
00:27:30,751 --> 00:27:33,173
by stabbing their needle-like mouth parts
340
00:27:33,190 --> 00:27:35,840
into the veins of leaves and stems
341
00:27:35,923 --> 00:27:37,956
and extracting the sap.
342
00:27:38,706 --> 00:27:41,459
They don't even need to suck.
343
00:27:41,673 --> 00:27:43,790
The pressure inside the plant
344
00:27:43,823 --> 00:27:47,178
is enough to squirt the sap into their stomachs.
345
00:27:50,512 --> 00:27:54,217
Mealybugs are also sap drinkers.
346
00:27:54,428 --> 00:27:57,644
They produce a waxy powder from their skin,
347
00:27:57,678 --> 00:27:59,650
which most predators dislike,
348
00:27:59,817 --> 00:28:03,284
so that they are able to drink unmolested out in the open.
349
00:28:07,817 --> 00:28:10,534
Snail rip through the vegetation
350
00:28:10,550 --> 00:28:14,856
rasping off mouthfuls with a long file-like tongue.
351
00:28:21,072 --> 00:28:23,511
A single snail can consume
352
00:28:23,528 --> 00:28:26,377
a fifth of the weight of its body, shell and all,
353
00:28:26,478 --> 00:28:28,061
in a single day.
354
00:28:36,644 --> 00:28:39,571
So insects and other small creatures,
355
00:28:39,683 --> 00:28:41,783
some helpful, some harmful,
356
00:28:41,933 --> 00:28:44,066
flourish through the summer.
357
00:28:46,733 --> 00:28:50,366
This is the time when most of them reproduce.
358
00:28:50,983 --> 00:28:54,538
And they do so with staggering speed.
359
00:28:56,838 --> 00:29:00,705
Female aphids mate and lay eggs like other insects,
360
00:29:00,738 --> 00:29:02,889
but they also produce clones,
361
00:29:03,155 --> 00:29:07,072
babies that hatch from unfertilized eggs.
362
00:29:08,327 --> 00:29:10,126
And the clones themselves,
363
00:29:10,127 --> 00:29:12,527
even before they leave the female's body,
364
00:29:12,577 --> 00:29:16,927
are already pregnant with other clones.
365
00:29:22,216 --> 00:29:24,616
Such telescope generations
366
00:29:24,632 --> 00:29:27,316
enable aphids to infest a whole plant
367
00:29:27,399 --> 00:29:29,449
in a matter of hours.
368
00:29:33,754 --> 00:29:37,238
But aphids are themselves food for others
369
00:29:37,438 --> 00:29:41,438
and assemblies like these don't go unnoticed
370
00:29:42,971 --> 00:29:45,471
by other insects.
371
00:29:47,826 --> 00:29:49,593
Among the most ferocious,
372
00:29:49,693 --> 00:29:52,576
are the many kinds of ladybird
373
00:29:53,260 --> 00:29:54,710
and their lavae.
374
00:29:56,860 --> 00:30:00,259
This is the young of a ladybird called Cryptolaeumus
375
00:30:00,410 --> 00:30:02,276
and it eats virtually nothing
376
00:30:02,382 --> 00:30:05,203
but Mealybugs and aphids
377
00:30:06,198 --> 00:30:09,298
when young and as an adult.
378
00:30:15,237 --> 00:30:18,837
This is a fasting moving young of a hoverfly.
379
00:30:31,976 --> 00:30:35,642
This larva of a lacewing is totally blind,
380
00:30:35,726 --> 00:30:38,076
but it doesn't need to see.
381
00:30:39,992 --> 00:30:42,481
It has an acute sense of smell
382
00:30:42,614 --> 00:30:47,763
and is specially sensitive to the pheromones produced by aphids.
383
00:30:48,014 --> 00:30:49,448
It attacks its prey
384
00:30:49,464 --> 00:30:52,990
by impaling them on a large hook in its mouth
385
00:30:53,164 --> 00:30:55,614
and then sucking them dry.
386
00:30:58,603 --> 00:31:01,822
And it has an unquenchable appetite.
387
00:31:03,920 --> 00:31:07,903
It could eat up to 600 aphids before it's adult.
388
00:31:11,525 --> 00:31:14,958
Most predators aren't fussy about the plants they live on
389
00:31:15,092 --> 00:31:17,442
as long as there is prey to hunt.
390
00:31:20,475 --> 00:31:21,733
But one predator
391
00:31:21,824 --> 00:31:24,608
has formed a special partnership with a plant
392
00:31:24,714 --> 00:31:28,014
that looks rather like the insect-eating sundew.
393
00:31:30,230 --> 00:31:31,180
This plant,
394
00:31:31,664 --> 00:31:33,864
which is called Roridula,
395
00:31:34,314 --> 00:31:36,197
also catches insects
396
00:31:36,397 --> 00:31:40,602
which get stuck to these sticky hairs on its leaves.
397
00:31:49,469 --> 00:31:50,741
Oddly enough,
398
00:31:50,791 --> 00:31:54,974
Roridula can't digest insect bodies.
399
00:31:55,791 --> 00:31:57,974
Instead, it gets help
400
00:31:58,008 --> 00:32:01,708
from one particular kind of insect called capsid bug,
401
00:32:02,324 --> 00:32:05,691
which lives nowhere else but on Roridula.
402
00:32:08,096 --> 00:32:10,546
And the capsid bug runs around
403
00:32:10,680 --> 00:32:12,896
on these leaves without getting stuck
404
00:32:14,063 --> 00:32:18,968
because its body is coated with a non-stick substance.
405
00:32:21,885 --> 00:32:23,202
And the capsid bug
406
00:32:23,402 --> 00:32:26,735
goes and feeds on the bodies of the insects
407
00:32:26,785 --> 00:32:29,018
the Roridula has caught.
408
00:32:31,168 --> 00:32:34,607
And when an insect lands and is caught,
409
00:32:34,674 --> 00:32:36,640
the capsid bug runs across,
410
00:32:36,790 --> 00:32:40,757
sticks its mouth part into the insect body
411
00:32:40,790 --> 00:32:42,757
and sucks it dry.
412
00:33:11,715 --> 00:33:14,606
Then it produces droppings which fall to the ground
413
00:33:14,956 --> 00:33:18,390
and those can feed Roricula.
414
00:33:26,040 --> 00:33:28,078
The carefully controlled conditions
415
00:33:28,091 --> 00:33:30,373
inside Kew's glass houses
416
00:33:30,476 --> 00:33:32,604
certainly suit plants.
417
00:33:33,822 --> 00:33:34,809
But equally,
418
00:33:35,053 --> 00:33:36,899
they suit insects.
419
00:33:39,775 --> 00:33:43,454
So something has to be done to keep pests in check.
420
00:33:46,428 --> 00:33:50,377
One way is to introduce predators -
421
00:33:52,183 --> 00:33:55,183
Asian water dragons.
422
00:33:59,791 --> 00:34:02,779
They exists on a diet of mealworms
423
00:34:02,945 --> 00:34:04,740
and cockroaches.
424
00:34:15,295 --> 00:34:18,158
They quickly learn that daily hosing down
425
00:34:18,180 --> 00:34:20,555
will drive the cockroaches out of the cracks
426
00:34:20,556 --> 00:34:22,658
where they hide during the day.
427
00:34:55,718 --> 00:34:59,230
There are also more subtle ways of controlling pests
428
00:34:59,282 --> 00:35:01,705
that visitors seldom notice.
429
00:35:02,683 --> 00:35:06,145
These cards have been coated with microscopic eggs
430
00:35:06,530 --> 00:35:07,748
of a wasp.
431
00:35:15,495 --> 00:35:16,648
When they hatch,
432
00:35:16,649 --> 00:35:20,380
the young wasps go off and search for their favorite prey -
433
00:35:21,688 --> 00:35:22,944
aphids.
434
00:35:32,551 --> 00:35:35,884
This one has discovered aphid pupae.
435
00:35:37,153 --> 00:35:39,050
It selects its target
436
00:35:39,089 --> 00:35:42,063
and injects it with an egg of its own.
437
00:35:43,849 --> 00:35:46,388
When the larva hatches within its host,
438
00:35:46,426 --> 00:35:48,632
it will eat it alive,
439
00:35:49,426 --> 00:35:51,606
just as others have done before it.
440
00:35:55,183 --> 00:35:58,633
These are the dried out husks of victims -
441
00:36:01,636 --> 00:36:03,340
aphid mummies.
442
00:36:15,691 --> 00:36:19,768
Kew is starting its next great seasonal transformation -
443
00:36:21,140 --> 00:36:22,217
autumn.
444
00:36:31,298 --> 00:36:32,823
Plants growing outside
445
00:36:32,836 --> 00:36:35,144
without the protection of the glass houses
446
00:36:35,221 --> 00:36:38,349
must get ready for the bad conditions that are coming.
447
00:36:39,917 --> 00:36:42,737
Trees prepare to lose their leaves.
448
00:36:43,391 --> 00:36:45,468
The green chlorophyll inside them
449
00:36:45,481 --> 00:36:49,109
begins to break down to be reabsorbed.
450
00:36:50,075 --> 00:36:54,100
The bright colors are byproducts of the process.
451
00:37:05,848 --> 00:37:07,552
As the leaves fall,
452
00:37:07,605 --> 00:37:10,117
a new world reveals itself
453
00:37:10,246 --> 00:37:12,233
from beneath the soil.
454
00:37:17,861 --> 00:37:19,194
Fungi.
455
00:37:29,647 --> 00:37:32,262
Fungi can't photosynthesize
456
00:37:32,288 --> 00:37:35,356
because, unlike plants, they have no chlorophyll.
457
00:37:37,228 --> 00:37:40,601
In fact, they are more closely related to animals
458
00:37:40,664 --> 00:37:42,304
and are made of chitin,
459
00:37:42,420 --> 00:37:46,382
the material insects use for their skeletons.
460
00:37:52,107 --> 00:37:55,186
These are the fruiting bodies of a fungus.
461
00:37:55,527 --> 00:37:58,799
Their function is to produce dust-like spores
462
00:37:58,800 --> 00:38:01,652
which are then blown away through the woodland
463
00:38:01,897 --> 00:38:03,522
to grow elsewhere.
464
00:38:04,261 --> 00:38:07,692
But these are only a tiny part of the fungus.
465
00:38:07,954 --> 00:38:10,761
Most of the body of the fungus
466
00:38:10,908 --> 00:38:12,113
is beneath the ground,
467
00:38:12,136 --> 00:38:14,373
a tangle of tiny treads
468
00:38:14,374 --> 00:38:17,903
which extend for hundreds of yards.
469
00:38:18,005 --> 00:38:19,312
through the forest.
470
00:38:19,812 --> 00:38:21,630
And we are now begin to realize
471
00:38:21,892 --> 00:38:24,608
that those threads are essential
472
00:38:24,983 --> 00:38:26,653
to the growth and health
473
00:38:26,869 --> 00:38:28,812
of many of the woodland plants.
474
00:38:41,136 --> 00:38:45,302
The length of these threads is almost unbelievable.
475
00:38:50,370 --> 00:38:52,301
One specimen in America
476
00:38:52,336 --> 00:38:56,472
was found to extend across nearly four square miles.
477
00:38:56,774 --> 00:38:59,376
That's an area 16 times bigger
478
00:38:59,455 --> 00:39:01,490
than Kew Gardens itself.
479
00:39:03,330 --> 00:39:04,671
Technically speaking,
480
00:39:04,717 --> 00:39:08,501
it's the largest known living organism on the plant.
481
00:39:20,859 --> 00:39:22,649
Most fungi make a living
482
00:39:22,661 --> 00:39:25,929
by feeding on the dead tissues of other organisms,
483
00:39:26,070 --> 00:39:28,104
both plant and animal.
484
00:39:45,758 --> 00:39:47,974
They produce powerful chemicals
485
00:39:47,985 --> 00:39:49,718
that enable them to break down
486
00:39:49,730 --> 00:39:52,912
about 90 percent of all organic matter,
487
00:39:53,934 --> 00:39:56,287
including leaves and wood.
488
00:39:59,480 --> 00:40:00,616
In doing this,
489
00:40:00,673 --> 00:40:03,127
they release the nutrients to the soil
490
00:40:03,128 --> 00:40:06,565
that plants need to fuel their new growth in the spring.
491
00:40:07,690 --> 00:40:11,013
So fungi are essential links
492
00:40:11,111 --> 00:40:13,202
in the cycle of life.
493
00:40:17,156 --> 00:40:20,560
But some fungi establish partnerships with plants
494
00:40:20,583 --> 00:40:22,787
while the plants are still alive.
495
00:40:24,015 --> 00:40:26,481
And they are just as important.
496
00:40:29,083 --> 00:40:32,026
This is the Lucombe Oak.
497
00:40:32,453 --> 00:40:36,521
It germinated from an acorn in the year 1762
498
00:40:36,691 --> 00:40:39,384
and is one of the oldest plants in Kew.
499
00:40:39,987 --> 00:40:43,157
It's roots are covered with a fungus.
500
00:40:43,617 --> 00:40:45,134
But that's not a friction.
501
00:40:45,595 --> 00:40:49,322
That's the reason why this tree was able to live for so long
502
00:40:50,118 --> 00:40:52,606
because the fungus can do something
503
00:40:52,629 --> 00:40:54,061
that the oak tree can't.
504
00:40:54,402 --> 00:40:57,561
It can extract nitrogen directly from the soil
505
00:40:58,038 --> 00:41:00,845
and then the oak tree collect it from the fungus.
506
00:41:01,283 --> 00:41:04,192
And in return, the fungus takes sugars
507
00:41:04,419 --> 00:41:06,783
from the sap in the roots of the oak tree.
508
00:41:07,499 --> 00:41:10,601
So it's a mutually convenient arrangement,
509
00:41:10,613 --> 00:41:12,976
an symbiotic relationship.
510
00:41:13,460 --> 00:41:14,993
In fact, we now know
511
00:41:14,994 --> 00:41:19,653
that around 90 percent of the species of plants on the earth
512
00:41:20,130 --> 00:41:22,789
depend upon fungi one way or another.
513
00:41:24,829 --> 00:41:26,862
Kew cares for fungi
514
00:41:26,920 --> 00:41:29,057
just as it does for plants.
515
00:41:29,682 --> 00:41:33,784
A special underground world has been created for them.
516
00:41:38,767 --> 00:41:41,789
Here, thousands of different species
517
00:41:41,938 --> 00:41:44,019
are preserved in boxes.
518
00:41:47,017 --> 00:41:48,642
This is the fungarium.
519
00:41:49,324 --> 00:41:52,869
There are more specimens of fungi here
520
00:41:52,972 --> 00:41:54,868
than anywhere else in the world,
521
00:41:54,869 --> 00:41:57,319
one and a quarter million of them.
522
00:41:57,796 --> 00:41:59,056
And such has come
523
00:41:59,091 --> 00:42:02,001
from all over the world, here to Kew,
524
00:42:02,057 --> 00:42:03,796
in order to study them.
525
00:42:05,785 --> 00:42:09,086
The fungarium contains specimens that Kew has collected
526
00:42:09,098 --> 00:42:12,257
through out the course of its 400-year history.
527
00:42:15,154 --> 00:42:17,688
They are stored for their potential value
528
00:42:17,859 --> 00:42:19,586
in science and medicine.
529
00:42:21,336 --> 00:42:24,513
Perhaps the most famous is this one.
530
00:42:25,308 --> 00:42:27,638
This is Penicillium,
531
00:42:27,695 --> 00:42:31,206
a mold from which we get penicillin.
532
00:42:32,229 --> 00:42:35,592
Here's another which is able to digest oil.
533
00:42:35,894 --> 00:42:37,689
And scientists are working to see
534
00:42:37,712 --> 00:42:41,098
whether it could be used for in cleaning up oil spills.
535
00:42:42,132 --> 00:42:44,678
But fungi can also be very sinister.
536
00:42:46,394 --> 00:42:49,235
This caterpillar has a fungus
537
00:42:49,246 --> 00:42:51,184
growing from its head.
538
00:42:52,070 --> 00:42:54,798
It's a species of Cordyceps,
539
00:42:54,957 --> 00:42:56,411
a tropical fungus
540
00:42:56,445 --> 00:42:59,525
that has developed a gruesome power.
541
00:43:00,968 --> 00:43:04,139
They can infect the brain of an animal.
542
00:43:04,554 --> 00:43:06,735
One infects ants
543
00:43:06,736 --> 00:43:10,361
and causes ants to climb up a grass stem,
544
00:43:10,963 --> 00:43:13,031
tamp its jaws on the top,
545
00:43:13,304 --> 00:43:15,565
and there, high up on the plant,
546
00:43:15,656 --> 00:43:17,508
the fungus kills it.
547
00:43:24,071 --> 00:43:27,889
A long fruiting body then bursts out of the ant's brain.
548
00:43:31,611 --> 00:43:33,395
This elaborate behavior
549
00:43:33,430 --> 00:43:36,555
enables the fungus to rise high above the ground
550
00:43:36,600 --> 00:43:39,497
and shower its spores over great distances
551
00:43:39,498 --> 00:43:42,589
and so reach new victims.
552
00:43:47,822 --> 00:43:50,879
The world of plants is still full of secrets
553
00:43:50,890 --> 00:43:53,390
even though we have so many different ways
554
00:43:53,402 --> 00:43:55,788
of investigating their lives.
555
00:44:01,624 --> 00:44:03,838
One of the most famous species
556
00:44:03,839 --> 00:44:07,430
has been something of a mystery until only a few years ago.
557
00:44:09,271 --> 00:44:11,044
It may look like a tree,
558
00:44:11,198 --> 00:44:15,709
but in reality, this is just a single giant leaf.
559
00:44:17,880 --> 00:44:20,425
It's called the titian arum
560
00:44:20,823 --> 00:44:23,380
and it's a record breaker.
561
00:44:25,818 --> 00:44:28,113
But not because of what you see now.
562
00:44:28,624 --> 00:44:29,873
In a week or so,
563
00:44:30,011 --> 00:44:33,306
that green stem and the leaflets that go on top
564
00:44:33,624 --> 00:44:35,704
will die, and rot,
565
00:44:35,852 --> 00:44:37,011
and disappear.
566
00:44:37,630 --> 00:44:39,494
But beneath the surface of the soil,
567
00:44:39,505 --> 00:44:42,153
there is a gigantic tuber,
568
00:44:42,449 --> 00:44:43,653
and it's from that
569
00:44:43,812 --> 00:44:46,324
that the record breaker will emerge.
570
00:44:53,773 --> 00:44:55,795
This extraordinary event
571
00:44:55,796 --> 00:44:59,705
occurs just once every seven years.
572
00:45:00,875 --> 00:45:03,591
It will take two months to complete.
573
00:45:26,524 --> 00:45:29,842
But this new growth is neither a trunk,
574
00:45:29,853 --> 00:45:31,581
nor a leaf.
575
00:45:38,746 --> 00:45:42,675
It's the bud of the biggest flower in the world.
576
00:45:55,763 --> 00:45:58,468
As it grows day after day,
577
00:45:58,627 --> 00:46:01,541
a huge spire, the spadix,
578
00:46:01,678 --> 00:46:05,406
rises from the center of the developing flower.
579
00:46:10,735 --> 00:46:14,803
And then one evening as darkness falls over the forest,
580
00:46:15,150 --> 00:46:18,184
the giant flower opens.
581
00:46:34,372 --> 00:46:39,697
This, surely, is one of the most astonishing of blooms.
582
00:46:46,958 --> 00:46:50,685
I first saw one of these amazing flowers
583
00:46:50,788 --> 00:46:54,901
growing in the wild in the tropical rainforest of Sumatra.
584
00:46:55,163 --> 00:46:57,373
But why are they so big?
585
00:46:58,089 --> 00:47:01,239
Well, the function of the flower, like all flowers,
586
00:47:01,632 --> 00:47:03,452
is to attract pollinator.
587
00:47:03,796 --> 00:47:07,928
And this plant gives off the smell of rotting flesh.
588
00:47:08,796 --> 00:47:11,141
But it does something else.
589
00:47:11,617 --> 00:47:15,748
Something you can see with a heat sensitive camera.
590
00:47:20,502 --> 00:47:22,599
This remarkable device
591
00:47:22,650 --> 00:47:25,404
reveals something astonishing.
592
00:47:33,076 --> 00:47:35,634
The white areas at the base of the spire
593
00:47:35,667 --> 00:47:37,404
are significantly hotter
594
00:47:37,454 --> 00:47:39,569
than the surrounding plant.
595
00:47:41,421 --> 00:47:43,126
It's heating up.
596
00:47:45,831 --> 00:47:47,060
At its hottest,
597
00:47:47,061 --> 00:47:50,667
the spire can reach 37 degrees centigrade,
598
00:47:50,700 --> 00:47:54,537
the same temperature as the body of a mammal.
599
00:47:59,816 --> 00:48:02,733
And as it warms, something else happens
600
00:48:02,766 --> 00:48:05,737
inside the flower at the base of the spire.
601
00:48:08,915 --> 00:48:14,046
Hundreds of smaller structures begin to produce stringy pollen.
602
00:48:25,833 --> 00:48:28,522
The titan arum is readying itself
603
00:48:28,571 --> 00:48:32,243
for the arrival of pollinating insects.
604
00:48:34,982 --> 00:48:38,932
Tiny sweat-bees and probably carrion beetles as well
605
00:48:39,064 --> 00:48:44,441
are attracted by a combination of the powerful smell and the heat.
606
00:48:46,425 --> 00:48:50,310
Other flowers that smell of carrion also produce heat.
607
00:48:50,474 --> 00:48:52,736
So it seems that what is happening
608
00:48:52,851 --> 00:48:55,112
is that they are mimicking the warmth
609
00:48:55,113 --> 00:48:57,572
of the body of recently dead animal.
610
00:48:58,556 --> 00:49:00,736
But the hot air
611
00:49:00,819 --> 00:49:03,819
produced in pulses from the top narrow spire
612
00:49:04,016 --> 00:49:05,819
must have a different function.
613
00:49:09,294 --> 00:49:10,353
At night,
614
00:49:10,447 --> 00:49:13,755
a layer of cold air, still air,
615
00:49:13,768 --> 00:49:17,918
forms between the forest canopy and the forest floor.
616
00:49:18,361 --> 00:49:21,197
But the spire of the titan arum
617
00:49:21,249 --> 00:49:23,738
producing the pulses of warm air
618
00:49:23,947 --> 00:49:25,882
pierces that barrier
619
00:49:25,883 --> 00:49:28,000
so that the smell of the titan arum
620
00:49:28,093 --> 00:49:30,312
spreads out of the top of the canopy
621
00:49:30,443 --> 00:49:31,913
far and wide.
622
00:49:31,984 --> 00:49:34,099
so attracting insects,
623
00:49:34,234 --> 00:49:37,476
pollinating insects, from a long way away.
624
00:49:39,956 --> 00:49:42,224
If we could imagine such a spectacle,
625
00:49:42,250 --> 00:49:45,045
it would look something like smoke from a chimney
626
00:49:45,161 --> 00:49:48,032
discharging heat into the night sky.
627
00:49:57,960 --> 00:50:01,639
It remains in bloom for just two days.
628
00:50:06,625 --> 00:50:08,729
And then, it closes.
629
00:50:32,160 --> 00:50:33,968
Science has given us a glimpse
630
00:50:33,981 --> 00:50:36,288
into a hitherto unseen world.
631
00:50:36,574 --> 00:50:39,869
However, our journey of discovery has only just started.
632
00:50:40,408 --> 00:50:42,459
As technology advances,
633
00:50:42,562 --> 00:50:44,433
so will our understanding
634
00:50:44,497 --> 00:50:47,318
of the hidden world of plants.
635
00:50:52,578 --> 00:50:55,437
The final frontier of plant discovery
636
00:50:55,553 --> 00:50:58,181
is in the dry zone.
637
00:51:03,284 --> 00:51:04,312
In deserts,
638
00:51:04,339 --> 00:51:07,429
plants use an extraordinary adaptations
639
00:51:07,441 --> 00:51:09,185
in order to survive
640
00:51:10,262 --> 00:51:12,749
by day and by night.
641
00:51:21,817 --> 00:51:23,933
And as we will discover,
642
00:51:24,048 --> 00:51:28,215
new research into plants' astonishing time capsules of life -
643
00:51:28,304 --> 00:51:29,625
their seeds -
644
00:51:29,753 --> 00:51:31,702
could ensure that no plant
645
00:51:31,732 --> 00:51:34,539
need ever become extinct again.
646
00:51:35,305 --> 00:52:35,916
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