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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 techniques and in 3D,
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we can unravel their deepest secrets.
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We can move from our time scale to theirs.
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We can see how they struggle with one another,
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how they get help from some animals
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but have the battle with others,
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and survive against the odds.
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And we can watch all these dramas taking place
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in a way that is impossible in the wild
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in one unique institution.
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the Royal Botanic Gardens at Kew.
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In this living laboratory,
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we can discover plants' most extreme adaptations for survival
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and we can glimpse Kew's tiny weapons
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in the battle to protect the future of all plants -
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seeds.
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Kingdom of Plants with David Attenborough
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Ever since plants first moved out of water and colonized the land,
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they've advanced into drier and drier places
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and evolved specially set-up adaptations
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in order that they can do so.
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Today, deserts cover about a third of the land's surface of the earth
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and they are spreading rapidly.
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But some plants have developed some truly extraordinary strategies
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to enable them to survive in the driest of places.
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Survival
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In deserts where water is scarce,
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one major strategy is to remain passive during the day
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when temperatures soar
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and only become active in the cool of the night.
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This desert in Kew's Princess of Wales Conservatory
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contains plants from every regions all around the world.
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And in mid-summer,
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one plant here does something truly astonishing.
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Don't be deceived by the shrivel untidy appearance of this cactus.
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This, in fact, one of the most remarkable members of the cactus family,
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is called Hylocereus -
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"the Queen of the Night".
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It lives in Mexico
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where, during the summer midday,
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the temperatures can reach a crippling 50 degrees centigrade.
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So during the day, it doesn't do much.
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But once a year,
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for one night only,
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it becomes a thing of astounding beauty.
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The flowers usually open on a night of the full moon.
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And as they do so, they give off a smell
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which attracts night flying animals, large and small.
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And as they get nearer,
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they can see the great white flowers,
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bright in the light of full moon.
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And they go to them to sip the nectar
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and, in doing so, pollinate the cactus.
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It might seem strange, even risky
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for the plant to restrict its flowering to just one night of the year.
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But this strategy works for Hylocereus.
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Its flowers are the biggest and brightest around
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and they offer its pollinators a nectar banazar -
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bats.
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With the aid of technology, we can imagine them,
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thousands of miles from their natural habitat,
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here in Kew.
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Bats pollinate all kinds of cacti.
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In spring time in Southern American deserts,
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there is always a cactus of one kind or another in bloom.
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A multitude of species compete for the attentions of nocturnal pollinators
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using bright pedals and powerful scent.
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The sweetest perfumes attract insects.
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But flowers that are pollinated by bats
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are rather more pungent.
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They give off the stench of rotting fruit.
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To nectar feeding bats,
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that smell is irresistible.
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They fly from cactus to cactus,
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sipping out the nectar.
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Each bat can consume more one and a half times its bodyweight of nectar.
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in a single night.
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Very tall columnar species,
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produce flowers right to the very top of their stems
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where they are easily smelt and seen,
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and easily reached.
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Some provide additional facilities.
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Espostoa guentheri from Bolivia
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sprouts a landing strip beneath its flowers,
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a pat of fur on which the bats can alight
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without damaging their wings on the spines.
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But in Mexico, bats and cacti
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have a even more extraordinary relationship.
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Each year, bats migrate across 1,000 miles of desert
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from central Mexico to Arizona.
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Pregnant females, 100,000 of them,
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are on their way to special maternity caves in the north
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where they will give birth to their young.
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The bats get all the nectar they need to sustain their journey
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and in return, they pollinate the cacti.
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This annual bat migration coincide exactly
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with the blooming of the night flowering cacti,
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so the bats can fly along a nectar corridor,
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and so can cross a patch of desert
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that, otherwise and at other times,
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would be impossible for them.
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By the time the bats return with their pups,
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the cacti are able once again to provide the bats with food,
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this time, their fruits.
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The bats carry with them in their stomach the fruit
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and the seed it contains.
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And in due course,
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they deposit those seeds with a nice little package of fertilizer
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farther down the corridor.
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So the corridors are self perpetuating.
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The bats, in effect, are cactus farmers.
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Perhaps the most extraordinary thing
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about these night blooming cacti
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is that, just a few hours after the flowers burst open,
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they begin to close.
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By the time the sun appears,
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they have already wilted and died.
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This is all part of their survival strategy.
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The closed pedals form a protective shield
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around the newly pollinated seeds
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locking vital moisture inside.
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The light of a new day
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reveals the bizarre nature of dry zone plants.
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These are surely some of the oddest looking species there are.
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And their strange shapes
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are a direct response to the harsh conditions.
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These plants will stay in the baking sun to collect the light they need,
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but they must also retain their moisture.
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Many do that by turning either their green stems
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or their waxy leaves into reservoirs.
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This extraordinary cactus from Mexico
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is covered in thick white hair.
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It's called "the old man".
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This fur not only provides shade,
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but restricts the circulation of the air around the surface of the stem
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and that reduces water loss.
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In even hotter and drier climates,
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some plants avoid the sun all together.
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This is Fenestraria -
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the window plant.
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It grows in the Kalahari Desert
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with most of its body buried beneath the soil.
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Only the blunt flat tips of its leaves are exposed.
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Each contains tiny lenses
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which transmit the sunlight down through the vertical leaf
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on to its green photosynthesizing cells.
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Some desert plants that live in exceptionally hot dry conditions
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take even more drastic measures.
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Leaves are very thin and have a large surface area
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so they lose a lot of moisture in heat.
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And many desert plants have done without them all together.
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Instead the valuable green pigment develops in the stems.
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And desert stems are often very thick and swollen
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and that enables a plant to store water in them.
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Not only that,
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but some desert plants have pleats in these stems
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so that when there is sudden rainstorm,
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those ridges can suck up all the moisture while it is there
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and expand in order to hold it.
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The stems of some of these species swell to such a degree
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that they become almost spherical.
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A sphere has the minimum surface area for any given volume
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and that enables the plant to hold as much water as possible.
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This one is Copiapoa from northern Chile
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where it never rains at all.
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But, in fact, it doesn't need it.
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Under a microscope, you can see why.
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There are thousands of tiny jagged structures
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on which the morning dew condenses
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so that the plant can collect it.
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But the ultimate is this plant.
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It's hidden between these light colored pebbles -
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Blossfeldia from Argentina.
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This is the only flowering plant
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that can withstand total desiccation
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for months on end.
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And then with a shower of rain or a little bit of water,
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it comes to life and produces a tiny little flower.
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This ability to wait for the right conditions
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is the trump card that enables many plants
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to survive in the dry zone.
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In many deserts,
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plants must endure months, sometimes, years, of drought.
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They do it by slowing down their metabolism
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and going into a state of virtual dormancy.
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But when rains finally arrive,
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plants like these suddenly come to life.
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Their dried out tissues absorb water like sponges.
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And once expanded,
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they use the moisture to grow.
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This primitive wakeless plant from the Chihuahuan Desert in Mexico
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is a spikemoss, Selaginella.
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It's also called "the resurrection plants"
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because its ability to seemingly come back from the dead.
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Rain starts a complex biochemical change in its cells
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that enables it to ramp up its metabolism
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and grow very quickly while it can.
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But the most spectacular consequence of rain in the desert
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is an explosion of color.
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Desert flowers are as colorful as any of the world.
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They have to attract pollinators quickly
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before the deserts dry out once again.
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But moisture in the soil could evaporate almost as quickly as it arrives
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and after a brief bloom, they die.
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Desert plants could only grow when the conditions are right
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and that maybe only for a few short periods in the year.
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So many desert plants
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take a long time to reach full size.
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That agave there, for example, is over 40 years old.
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But during that time,
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it has manufactured food and gathered water
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and stored them in its great fat leaves,
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but it's not yet adult.
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This one is.
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This agave has started to withdraw that water and food from it leaves.
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So now, they are beginning to crumple and wilt.
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And it uses that food
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to fuel the growth of this huge mast-like stem
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that grows from its center and will carry the flowers.
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And it reaches its full height at extraordinary speed.
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It can grow by a quarter of a meter everyday.
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It reaches such a height
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that here in Kew's glass house,
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panes have to be removed from the root to let it through.
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This infrequently flowering
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has given this species of agave a nick name -
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"the century plant".
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So why does the agave produce this huge tall mast?
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Well, some plants are pollinated by insects
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and you attract insects with smell.
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But this plant is pollinated by birds -
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humming birds.
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And birds have little or no sense of smell.
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To attract them, you have to exploit their very sharp sight.
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You have to produce flowers that are very bright
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and put them right at the top of a prominent tall mast.
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Growing at such a rate demands considerable effort.
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For the agave, it's terminal.
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The act of producing that mast
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is the last act in this plant's life.
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Having done it and been pollinated, it dies.
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Thanks to their extraordinary survival strategies,
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desert plants are able to thrive in places
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where others would die.
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But that makes them the focus of much unwanted attention.
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As a downside to success for a desert plant,
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the more water it stores,
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the more tempting it is for a thirsty animal to try and steal it.
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So desert plants have to have good defenses.
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The techniques they use can tell us something
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about the herbivores that try to feed on them.
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This Echinopsis from Argentina
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develops long strong spines
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as a defense against large grazing animals -
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llamas.
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But such defenses also provide hiding places
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where an insect or a spider can keep out of harm's way.
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There are other ways in which a plant can protect itself.
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You can disguise yourself,
262
00:23:09,198 --> 00:23:11,804
so you become virtually invisible
263
00:23:11,941 --> 00:23:14,378
as these stone plants have done.
264
00:23:14,379 --> 00:23:16,758
These are not pebbles as you might think.
265
00:23:16,788 --> 00:23:18,606
They are living plants.
266
00:23:23,029 --> 00:23:26,341
These are lithrobs from the deserts of Africa
267
00:23:26,371 --> 00:23:30,038
and their markings closely match their surroundings.
268
00:23:31,991 --> 00:23:33,986
What's more, they are varying color
269
00:23:34,062 --> 00:23:37,308
according to the rocks on which they grow.
270
00:23:37,470 --> 00:23:40,090
That's growing on pale rocks,
271
00:23:40,741 --> 00:23:43,271
and those on reddish rocks.
272
00:23:43,801 --> 00:23:48,528
Or you can load the water you contain
273
00:23:48,665 --> 00:23:51,512
with a particularly strong chemical
274
00:23:51,643 --> 00:23:54,309
which animals might find distasteful.
275
00:23:54,582 --> 00:23:57,747
This is the Peyote plant from Mexico.
276
00:23:58,081 --> 00:24:01,564
And its sap not only puts off animals,
277
00:24:01,595 --> 00:24:04,458
but has the property of suppressing pain,
278
00:24:04,680 --> 00:24:07,377
so the local people use it for that purpose
279
00:24:07,423 --> 00:24:10,177
and also in their religious rituals
280
00:24:10,269 --> 00:24:12,906
for it's also hallucinogenic.
281
00:24:20,125 --> 00:24:21,853
In colder regions,
282
00:24:21,944 --> 00:24:24,897
pine trees also have to conserve water
283
00:24:24,973 --> 00:24:26,139
for during the winter
284
00:24:26,153 --> 00:24:29,669
water in the soil is frozen and so beyond their reach.
285
00:24:30,290 --> 00:24:32,678
Little evaporate their leaves
286
00:24:32,705 --> 00:24:36,360
because they have been reduced to stiff tough needles.
287
00:24:39,162 --> 00:24:40,372
Like cacti,
288
00:24:40,464 --> 00:24:44,358
they also produce distasteful chemicals.
289
00:24:49,458 --> 00:24:53,457
The distinctive smell that you sense when you walk among pine trees
290
00:24:53,623 --> 00:24:55,955
come from volatile oils
291
00:24:56,001 --> 00:24:58,530
that the trees produce in their leaves.
292
00:24:59,174 --> 00:25:00,604
It's a form of defense.
293
00:25:01,035 --> 00:25:03,311
Most insects can't bear it,
294
00:25:03,588 --> 00:25:05,357
but one can -
295
00:25:05,388 --> 00:25:07,358
the pine aphid.
296
00:25:07,727 --> 00:25:09,526
When that attacks, however,
297
00:25:09,664 --> 00:25:12,909
the pine trees have a second line of defense.
298
00:25:14,693 --> 00:25:20,307
They produce that volatile oil from the cuts made by the insects
299
00:25:20,492 --> 00:25:22,044
in even greater quantity
300
00:25:22,045 --> 00:25:26,736
and that crucially changes the nature of the smells around the trees.
301
00:25:29,288 --> 00:25:34,410
Aphids infestation triggers a complex chain reaction from the pines.
302
00:25:35,610 --> 00:25:37,702
Each time an aphid bites,
303
00:25:37,733 --> 00:25:40,639
the pine releases oily vapor from the wound
304
00:25:40,685 --> 00:25:42,884
which fills the surrounding air.
305
00:25:45,991 --> 00:25:50,344
This triggers the release of further volatiles from other branches,
306
00:25:51,252 --> 00:25:53,528
even other trees.
307
00:25:58,495 --> 00:26:00,002
The effect multiplies
308
00:26:00,017 --> 00:26:05,262
until eventually whole forests become coat in pine scent.
309
00:26:14,705 --> 00:26:19,366
This scent cloud attracts predatory ladybirds.
310
00:26:19,797 --> 00:26:21,610
They are as sensitive to it
311
00:26:21,611 --> 00:26:24,087
as sharks are to blood.
312
00:26:39,683 --> 00:26:42,466
This is the eyed ladybird
313
00:26:42,528 --> 00:26:45,542
and it preys on pine aphids.
314
00:26:50,648 --> 00:26:52,832
It locates an infestation
315
00:26:52,833 --> 00:26:55,770
by following the trail of volatiles.
316
00:27:00,460 --> 00:27:01,830
And once there,
317
00:27:01,968 --> 00:27:05,136
it makes short work of the prey.
318
00:27:15,455 --> 00:27:18,348
It's a mutually beneficial arrangement.
319
00:27:18,808 --> 00:27:21,470
The ladybird gets an easy meal
320
00:27:24,023 --> 00:27:27,515
and the pine tree gets rid of a pest.
321
00:27:37,341 --> 00:27:39,695
Some dry zone plants use oils
322
00:27:39,772 --> 00:27:43,048
to defend themselves from other dangers,
323
00:27:43,325 --> 00:27:46,615
not from insects but other plants.
324
00:27:48,169 --> 00:27:50,507
This is a eucalyptus,
325
00:27:50,676 --> 00:27:53,384
famous for the oil in its leaves.
326
00:27:53,707 --> 00:27:56,398
It produces that oil in such quantity
327
00:27:56,551 --> 00:27:57,920
that, under certain conditions,
328
00:27:57,935 --> 00:28:01,304
it can form a blue haze above the tree.
329
00:28:01,856 --> 00:28:05,749
In fact, the Blue Mountains of New South Wales in Australia
330
00:28:05,841 --> 00:28:08,040
get their name from the haze
331
00:28:08,071 --> 00:28:11,102
that hangs over eucalyptus forests sometimes.
332
00:28:11,270 --> 00:28:14,576
When the leaves fall to the ground and rot,
333
00:28:14,638 --> 00:28:17,538
the oil leaches out into the soil.
334
00:28:17,698 --> 00:28:21,571
And then, reinforced by more oil secreted by the roots,
335
00:28:21,787 --> 00:28:24,254
it acts as an inhibitor
336
00:28:24,321 --> 00:28:29,392
that prevents other seeds of other plants from growing around its base,
337
00:28:29,558 --> 00:28:33,456
so reducing competition for the eucalyptus.
338
00:28:36,123 --> 00:28:39,927
Another species uses oils in a different way
339
00:28:43,227 --> 00:28:45,843
and a more dramatic one.
340
00:28:48,797 --> 00:28:53,341
If the temperature raises to 32 degrees centigrade,
341
00:28:53,546 --> 00:28:57,462
those substances in the leaves of this Cistus plant from the Mediterranean
342
00:28:57,579 --> 00:29:00,829
can spontaneously burst into flame.
343
00:29:25,574 --> 00:29:29,249
The flames reduce the Cistus to a cinder
344
00:29:30,882 --> 00:29:34,393
and the plant itself will never recover.
345
00:29:36,786 --> 00:29:40,485
But this is not a disastrous accident.
346
00:29:40,551 --> 00:29:43,951
The Cistus has evolved to burn.
347
00:29:46,135 --> 00:29:50,639
Such extraordinary sacrifice ensures a different kind of survival -
348
00:29:50,671 --> 00:29:52,804
survival of its offspring.
349
00:29:55,437 --> 00:29:58,770
The flames will also destroy all other plants
350
00:29:58,836 --> 00:30:00,569
from the surrounding area
351
00:30:02,741 --> 00:30:04,607
and this gives the Cistus
352
00:30:04,617 --> 00:30:07,989
the chance to extend its territory.
353
00:30:21,852 --> 00:30:23,168
From the ashes,
354
00:30:23,260 --> 00:30:27,614
a new generation of Cistus quickly rises.
355
00:30:32,625 --> 00:30:35,071
Cistus seeds escape damage
356
00:30:35,159 --> 00:30:39,044
because they are enclosed in flame-resistant capsules.
357
00:30:40,202 --> 00:30:43,738
Further more, the spurt stimulates their germination.
358
00:30:51,947 --> 00:30:54,157
It has taken millions of years
359
00:30:54,328 --> 00:30:58,497
for such complex adaptations as this to evolve.
360
00:30:59,839 --> 00:31:00,996
But today,
361
00:31:01,141 --> 00:31:03,575
plants of the dry zone and beyond
362
00:31:03,667 --> 00:31:05,967
face a new threat.
363
00:31:11,979 --> 00:31:15,083
From rainforests to mountain ranges,
364
00:31:15,333 --> 00:31:18,924
the evidence is that plants across the world
365
00:31:18,977 --> 00:31:21,935
are disappearing in variety and number
366
00:31:22,002 --> 00:31:25,843
faster than at any other time in the earth history.
367
00:31:30,960 --> 00:31:36,853
Human beings are taking over more and more of the world's wild places,
368
00:31:41,074 --> 00:31:46,099
but human intervention can also be the key to their future survival.
369
00:31:52,082 --> 00:31:55,227
Kew is at the forefront of the effort.
370
00:31:57,029 --> 00:32:00,502
Its unique facilities enable scientists here
371
00:32:00,595 --> 00:32:02,988
to both measure the loss of species
372
00:32:03,054 --> 00:32:07,367
and work out how to prevent extinctions before it's too late.
373
00:32:09,958 --> 00:32:12,393
And a crucial resource in that battle
374
00:32:12,406 --> 00:32:14,707
is held in this building -
375
00:32:15,944 --> 00:32:17,049
the Herbarium.
376
00:32:25,717 --> 00:32:28,887
Its collection of preserved and dried specimens
377
00:32:28,939 --> 00:32:34,253
contains samples of 90 percent of all known plant specimens on earth.
378
00:32:42,461 --> 00:32:44,619
Here, almost unbelievably,
379
00:32:44,709 --> 00:32:49,314
there are records of every single specimen ever sent to Kew.
380
00:32:49,722 --> 00:32:52,721
It was founded in 1853.
381
00:32:53,035 --> 00:32:57,114
Now, staff process about 50,000 specimens
382
00:32:57,127 --> 00:33:01,243
that are sent every year from all over the world.
383
00:33:02,191 --> 00:33:06,282
It contains about eight million specimens.
384
00:33:06,387 --> 00:33:10,069
It's the biggest repository of botanical data in the world
385
00:33:10,135 --> 00:33:13,069
and Kew's major weapon in the battle
386
00:33:13,240 --> 00:33:15,392
to save the plants of the planet.
387
00:33:19,238 --> 00:33:21,622
This vast databank
388
00:33:21,685 --> 00:33:26,181
plays a vital part in monitoring the global health of plants.
389
00:33:28,023 --> 00:33:30,772
It's run by curator David Mabberley.
390
00:33:31,233 --> 00:33:33,746
This herbarium, eight million specimens,
391
00:33:34,075 --> 00:33:38,548
is actually a record of the vegetation of the earth through time.
392
00:33:38,798 --> 00:33:41,361
There are something which had gone completely extinct
393
00:33:41,504 --> 00:33:45,783
and so all that is known of them is just some herbaria specimens.
394
00:33:45,860 --> 00:33:49,596
For example, this is a relation of the olive,
395
00:33:49,806 --> 00:33:54,002
which was known only from one island off the coast of California.
396
00:33:54,093 --> 00:33:56,275
And it hasn't been seen since 1873.
397
00:33:56,342 --> 00:33:56,907
Really?
398
00:33:56,908 --> 00:34:00,248
Even then, there were only three and that's all that we've got left now.
399
00:34:00,363 --> 00:34:01,196
Goodness!
400
00:34:01,563 --> 00:34:05,932
These specimens, though, are referred to, aren't they? For identification.
401
00:34:06,069 --> 00:34:07,530
Yes, these are the standards.
402
00:34:07,945 --> 00:34:11,620
And the ones which are in these red folders like this are actually the ones
403
00:34:11,856 --> 00:34:14,774
upon which the original description of a plant was made,
404
00:34:14,805 --> 00:34:16,420
the so-called type specimen.
405
00:34:16,528 --> 00:34:18,373
And therefore this is the kind of gold standard.
406
00:34:18,404 --> 00:34:21,710
If anybody really wants to know what is meant by a particular plant name,
407
00:34:21,741 --> 00:34:23,680
they must refer to the type specimen.
408
00:34:25,647 --> 00:34:30,384
The path to saving endangered species often begins here.
409
00:34:32,692 --> 00:34:36,567
For example, back in 1874,
410
00:34:36,813 --> 00:34:39,090
this specimen was sent back
411
00:34:39,352 --> 00:34:43,042
from the Island of Rodrigues in the Indian Ocean
412
00:34:43,380 --> 00:34:45,657
of a tree they called the Cafe Marron -
413
00:34:45,703 --> 00:34:47,842
a kind of coffee.
414
00:34:48,348 --> 00:34:50,285
It was preserved here,
415
00:34:50,286 --> 00:34:53,917
given a Latin name and put in the Herbarium.
416
00:34:54,517 --> 00:34:56,899
And then, about 50 years later,
417
00:34:57,022 --> 00:35:02,237
people on Rodrigues realized that Cafe Marron had disappeared.
418
00:35:03,620 --> 00:35:07,312
Then, in 1979, someone found a plant.
419
00:35:07,327 --> 00:35:10,004
Was it, was it not Cafe Marron?
420
00:35:10,389 --> 00:35:14,663
A specimen was sent here, compared with this specimen
421
00:35:14,956 --> 00:35:17,079
and indeed it proved with the case.
422
00:35:17,462 --> 00:35:19,938
So, for that single plant,
423
00:35:19,969 --> 00:35:24,323
a cutting was taken and sent here to Kew for propagation.
424
00:35:27,090 --> 00:35:28,982
From that single cutting,
425
00:35:29,089 --> 00:35:33,965
horticulturists grew a handful of clone specimens.
426
00:35:34,350 --> 00:35:36,442
But although they flowered frequently,
427
00:35:36,534 --> 00:35:39,525
they never produced viable seed.
428
00:35:40,841 --> 00:35:42,978
Without the ability to reproduce,
429
00:35:43,240 --> 00:35:46,115
the Cafe Marron was still doomed.
430
00:35:48,792 --> 00:35:51,451
So the plant earned the nickname
431
00:35:51,529 --> 00:35:53,405
"the living dead".
432
00:36:09,538 --> 00:36:12,123
The daunting challenge of rescuing it
433
00:36:12,185 --> 00:36:15,659
was taken up by endangered plant specialist -
434
00:36:15,706 --> 00:36:17,844
Carlos Magdalena.
435
00:36:23,719 --> 00:36:27,503
After several months of experimentation with heat and light,
436
00:36:27,641 --> 00:36:32,255
he finally managed to induce the plant to produce seed.
437
00:36:33,762 --> 00:36:35,285
But when they germinated,
438
00:36:35,393 --> 00:36:39,560
the young plants had leaves so unlike the Cafe Marron he knew,
439
00:36:39,606 --> 00:36:41,898
he thought he must have made a mistake.
440
00:36:45,021 --> 00:36:47,572
That's quite different from Cafe Marron.
441
00:36:47,604 --> 00:36:48,782
It's rather different, isn't it?
442
00:36:48,783 --> 00:36:51,235
Different color, different leaf shape.
443
00:36:51,664 --> 00:36:53,294
So, were you surprised?
444
00:36:53,341 --> 00:36:57,187
Well, I was surprised in the way that I've never seen them before.
445
00:36:59,124 --> 00:37:03,676
This strange plant looks nothing like the herbaria sample.
446
00:37:04,644 --> 00:37:08,629
At first, nobody could be sure that was even the same species.
447
00:37:11,412 --> 00:37:12,982
But as it grew,
448
00:37:13,135 --> 00:37:14,628
it changed
449
00:37:14,888 --> 00:37:17,232
and eventually, it morphed
450
00:37:17,233 --> 00:37:20,655
into a recognizable adult plant.
451
00:37:22,255 --> 00:37:25,111
But what is the reason for this dramatic change
452
00:37:25,230 --> 00:37:27,578
as the Cafe Marron matures?
453
00:37:31,149 --> 00:37:34,621
The answer is camouflage.
454
00:37:36,820 --> 00:37:40,251
This is the most famous inhabitant
455
00:37:40,252 --> 00:37:43,315
of the Island of Rodrigues -
456
00:37:43,665 --> 00:37:46,064
a giant tortoise.
457
00:37:46,602 --> 00:37:49,184
It loves bananas.
458
00:37:51,576 --> 00:37:52,523
Go on.
459
00:37:54,045 --> 00:37:56,957
But they also likes green leaves
460
00:37:56,970 --> 00:37:59,246
and that's their main food.
461
00:38:02,071 --> 00:38:05,085
So any plant growing close to the ground
462
00:38:05,387 --> 00:38:07,755
has very little chance of survival
463
00:38:07,899 --> 00:38:12,148
while creatures like this are going around eating them.
464
00:38:12,515 --> 00:38:16,685
And that's the clue to the mystery of the Cafe Marron.
465
00:38:17,461 --> 00:38:20,724
When it's small, it produces leaves
466
00:38:21,105 --> 00:38:24,512
that are very thin and not even green.
467
00:38:24,565 --> 00:38:28,103
And the tortoise whose eyesight is not very good
468
00:38:28,247 --> 00:38:29,800
doesn't even see it.
469
00:38:29,852 --> 00:38:34,614
So he takes very little notice of leaves like these
470
00:38:35,114 --> 00:38:37,718
and the Cafe Marron can grow.
471
00:38:38,284 --> 00:38:39,547
As it grows,
472
00:38:39,902 --> 00:38:41,771
it becomes a bit bigger
473
00:38:42,086 --> 00:38:43,243
and still
474
00:38:43,667 --> 00:38:46,938
its leaves are thin and dark
475
00:38:46,978 --> 00:38:48,845
and rather inconspicuous.
476
00:38:49,332 --> 00:38:51,516
And it's not until
477
00:38:52,976 --> 00:38:55,067
it's really quite tall
478
00:38:55,712 --> 00:39:00,171
does the Cafe Marron plant produce its proper green leaves
479
00:39:00,461 --> 00:39:01,722
and its flowers.
480
00:39:01,802 --> 00:39:02,919
But by that time,
481
00:39:03,024 --> 00:39:07,576
it's well beyond the reach of a giant tortoise.
482
00:39:08,076 --> 00:39:10,536
So that is the solution
483
00:39:10,693 --> 00:39:12,495
to the Cafe Marron mystery
484
00:39:12,508 --> 00:39:15,205
that the plant produces two different leaves
485
00:39:15,376 --> 00:39:17,797
as a defense of being eaten.
486
00:39:30,476 --> 00:39:32,475
The Cafe Marron's survival
487
00:39:32,633 --> 00:39:36,238
is tribute to the skills developed here in Kew.
488
00:39:40,235 --> 00:39:43,656
But it is just one species.
489
00:39:45,931 --> 00:39:50,539
The ultimate aim is to safeguard all remaining plant species.
490
00:39:53,783 --> 00:39:56,033
And the maybe-way of doing that
491
00:39:56,059 --> 00:39:59,848
by using these extraordinary structures -
492
00:40:00,532 --> 00:40:01,716
seeds.
493
00:40:06,081 --> 00:40:11,198
A 3D microscope magnifies them up to 200 times
494
00:40:11,211 --> 00:40:13,948
and reveals how extraordinary complex
495
00:40:14,040 --> 00:40:16,316
the surface of a seed can be.
496
00:40:23,496 --> 00:40:26,219
No two species are the same.
497
00:40:28,706 --> 00:40:31,349
These images have been given artificial colors,
498
00:40:31,454 --> 00:40:35,005
but many of their shapes are beyond explanation.
499
00:40:36,742 --> 00:40:39,938
Some structures, however, have a clear function.
500
00:40:39,964 --> 00:40:43,727
They help the seed to achieve one of its main purposes -
501
00:40:43,767 --> 00:40:44,977
to travel.
502
00:40:46,106 --> 00:40:49,725
Many seeds rely on animal couriers.
503
00:40:50,106 --> 00:40:51,737
The American Stickseed
504
00:40:51,750 --> 00:40:55,103
attaches itself to the fur or skin of passing animals
505
00:40:55,170 --> 00:40:57,405
with hooks or barb spikes.
506
00:40:59,588 --> 00:41:02,720
The amazing sticking structures of such hitchhikers
507
00:41:02,786 --> 00:41:05,206
inspired the invention of Velcro.
508
00:41:07,389 --> 00:41:10,875
Some seeds carry a little package of nutritious fat
509
00:41:10,967 --> 00:41:15,215
which persuades an ant to take it back to its underground nest
510
00:41:15,294 --> 00:41:19,135
where the seed having surrendered its fatty reward to the ants
511
00:41:19,320 --> 00:41:21,292
can germinate in safety.
512
00:41:24,094 --> 00:41:26,671
The seeds of orchids are miniscule
513
00:41:26,724 --> 00:41:28,806
and produced in their millions.
514
00:41:30,131 --> 00:41:33,087
They blow away like dust.
515
00:41:34,631 --> 00:41:39,168
In contrast, this much bigger seed has a large flat membrane
516
00:41:39,247 --> 00:41:40,984
which serves as a wing
517
00:41:41,010 --> 00:41:44,758
so that it can float great distances on the wind.
518
00:41:47,113 --> 00:41:50,441
Other wind disperse seeds like the yellow paintbrush
519
00:41:50,467 --> 00:41:52,584
have a honey cone texture.
520
00:41:54,253 --> 00:41:56,160
Such complex sculpturing
521
00:41:56,161 --> 00:41:59,292
enables seeds to catch the slightest wind current
522
00:41:59,319 --> 00:42:00,989
and ride thermos
523
00:42:01,002 --> 00:42:04,278
traveling long distances from their mother plants.
524
00:42:06,896 --> 00:42:09,196
But these images also reveal
525
00:42:09,209 --> 00:42:13,760
the incredible toughness of the seed's outer capsule.
526
00:42:14,484 --> 00:42:16,576
This strength's maybe the key
527
00:42:16,681 --> 00:42:19,601
to the survival of all plants
528
00:42:20,286 --> 00:42:24,099
for seeds can survive all kinds of hardship.
529
00:42:26,821 --> 00:42:28,873
This plant is called the pincushion.
530
00:42:28,874 --> 00:42:30,952
and grows in South Africa.
531
00:42:32,136 --> 00:42:35,965
And this individual specimen is something of a miracle.
532
00:42:38,593 --> 00:42:40,804
In 1803,
533
00:42:41,133 --> 00:42:44,882
a British man of war captured a Dutch merchantman
534
00:42:45,132 --> 00:42:47,447
coming back from the Cape of Good Hope.
535
00:42:47,933 --> 00:42:52,076
And on board, in the cargo, they found a pack of seeds.
536
00:42:52,668 --> 00:42:53,824
When they got back to Britain,
537
00:42:53,825 --> 00:42:57,824
the seeds went to the trial of London for quite a long time.
538
00:42:58,061 --> 00:43:01,652
But eventually, they found their way here to Kew.
539
00:43:02,442 --> 00:43:03,692
And one of them,
540
00:43:04,072 --> 00:43:07,597
germinated and produced this plant
541
00:43:07,807 --> 00:43:09,622
after 200 years,
542
00:43:09,885 --> 00:43:15,319
just shows how long seeds can survive even without help.
543
00:43:18,291 --> 00:43:20,461
This ability to endure
544
00:43:20,500 --> 00:43:24,973
has inspired Kew's latest ground-breaking project.
545
00:43:35,232 --> 00:43:38,468
Its ultimate goal is to ensure the survival
546
00:43:38,481 --> 00:43:42,212
of every remaining species of plant on earth.
547
00:43:44,044 --> 00:43:46,583
The work takes place deep underground
548
00:43:46,609 --> 00:43:48,964
in a labyrinth of sealed vaults
549
00:43:48,978 --> 00:43:52,371
that are encased in steel and concrete.
550
00:43:57,369 --> 00:44:00,920
It's called the Kew Millennium Seed Bank.
551
00:44:03,498 --> 00:44:06,077
Its contents are so valuable
552
00:44:06,156 --> 00:44:09,445
that it was specifically designed to withstand the impact
553
00:44:09,537 --> 00:44:12,128
of a bomb or an air crash.
554
00:44:12,745 --> 00:44:15,100
Inside these vaults, there are seeds
555
00:44:15,257 --> 00:44:17,875
gathered from plants all over the world.
556
00:44:18,480 --> 00:44:23,795
In fact, as much as 10 percent of the world's known species
557
00:44:24,611 --> 00:44:26,319
are represented in there.
558
00:44:50,509 --> 00:44:52,871
The heart of the Seed Bank Project
559
00:44:52,941 --> 00:44:55,086
is this gigantic freezer
560
00:44:55,099 --> 00:44:58,426
full of seeds in sealed jars.
561
00:45:00,676 --> 00:45:05,043
The conditions inside are perfect for long term storage.
562
00:45:07,989 --> 00:45:11,764
But the job is aided by the very nature of seeds.
563
00:45:13,579 --> 00:45:17,183
The seed is the stage in which a plant can remain dormant
564
00:45:17,341 --> 00:45:20,854
waiting until conditions for germination are right.
565
00:45:25,602 --> 00:45:29,376
Inside the seed, there is a store of food.
566
00:45:29,652 --> 00:45:33,034
Outside, there's a tough protective shell
567
00:45:33,073 --> 00:45:35,847
to guard against predation or damage.
568
00:45:36,202 --> 00:45:39,794
In fact, the seed is a kind of time capsule
569
00:45:39,926 --> 00:45:42,293
that can live for sometimes a decade,
570
00:45:42,320 --> 00:45:44,463
sometimes even centuries.
571
00:45:44,766 --> 00:45:46,503
The aim of the Seed Bank
572
00:45:46,556 --> 00:45:49,527
is to prolong that period as long as possible.
573
00:45:49,750 --> 00:45:50,882
To do that,
574
00:45:51,092 --> 00:45:53,013
they clean the seeds,
575
00:45:53,263 --> 00:45:54,262
dry them,
576
00:45:54,420 --> 00:45:56,657
put them in jars like this,
577
00:45:57,183 --> 00:46:01,681
and then keep them here at minus 20 degrees centigrade.
578
00:46:01,982 --> 00:46:05,509
How long they will survive under these conditions?
579
00:46:05,601 --> 00:46:06,784
Nobody knows,
580
00:46:06,955 --> 00:46:10,560
but it's certainly going to be for a very long time.
581
00:46:14,137 --> 00:46:17,701
New samples arrive for the Seed Bank everyday.
582
00:46:20,253 --> 00:46:24,240
They are first identified and studied in microscopic detail
583
00:46:24,292 --> 00:46:27,897
by chief morphologist Dr. Wolfgang Stuppy.
584
00:46:29,947 --> 00:46:33,104
The latest report from Israeli paints that
585
00:46:33,340 --> 00:46:38,853
date palm seeds have been found in King Herod the Great's palace in Masada
586
00:46:38,879 --> 00:46:42,338
and they germinated after 2,000 years.
587
00:46:42,510 --> 00:46:45,112
So that is possible and this is
588
00:46:45,349 --> 00:46:48,993
the principle that naming "Seed Bank" is built upon.
589
00:46:48,994 --> 00:46:52,348
that seeds can survive for millennium if necessary.
590
00:46:55,177 --> 00:46:58,450
The longevity of most kinds of seeds is unknown,
591
00:46:59,648 --> 00:47:02,330
so they must be regularly checked.
592
00:47:09,053 --> 00:47:14,024
Samples of seeds are periodically removed from the vaults and germinated
593
00:47:35,857 --> 00:47:37,501
If most grow,
594
00:47:37,555 --> 00:47:41,771
the whole batch will be left in the vaults for another decade.
595
00:47:46,394 --> 00:47:49,381
And sometimes a sample fails,
596
00:47:50,039 --> 00:47:51,589
like these anemone seeds,
597
00:47:51,602 --> 00:47:54,956
which, although germinating in sterilized conditions,
598
00:47:54,983 --> 00:47:57,496
become chocked with fungus.
599
00:48:05,413 --> 00:48:06,650
When this happens,
600
00:48:06,716 --> 00:48:09,622
the scientists must find out why
601
00:48:09,741 --> 00:48:12,136
and how to prevent it from happening again.
602
00:48:17,211 --> 00:48:20,619
The Seed Bank Project is still in its infancy
603
00:48:21,934 --> 00:48:25,605
but the evidence is that there is no time to lose.
604
00:48:27,486 --> 00:48:30,406
There are already seeds stored here from plants
605
00:48:30,485 --> 00:48:33,155
that are now extinct in the wild.
606
00:48:34,389 --> 00:48:36,967
The problem is, well, many people don't understand,
607
00:48:37,060 --> 00:48:39,574
is that if a species got extinct,
608
00:48:40,059 --> 00:48:43,349
it means it's gone for us forever.
609
00:48:43,823 --> 00:48:47,096
There were five mass extinctions in the earth history.
610
00:48:47,544 --> 00:48:49,282
After every mass extinction,
611
00:48:49,306 --> 00:48:51,963
it took between 4 and 20 million years
612
00:48:51,964 --> 00:48:55,226
for biodiversity to bounce back to pre-extinction levels.
613
00:48:56,121 --> 00:48:59,712
Now, clearly we cannot wait four million years
614
00:48:59,947 --> 00:49:03,143
for life to bounce back.
615
00:49:03,827 --> 00:49:05,892
So if we don't keep seeds here
616
00:49:06,168 --> 00:49:08,471
and this plant species got extinct,
617
00:49:08,866 --> 00:49:12,273
it will be lost to mankind forever.
618
00:49:15,889 --> 00:49:18,203
Thankfully, there is a great momentum
619
00:49:18,244 --> 00:49:20,716
behind the Seed Bank Project.
620
00:49:22,519 --> 00:49:24,386
Over the next a few decades,
621
00:49:24,544 --> 00:49:28,031
these shelves will be filled to capacity.
622
00:49:36,566 --> 00:49:39,880
There's enough space here to hold seed
623
00:49:39,972 --> 00:49:44,642
from every single species of plants on this planet.
624
00:49:45,445 --> 00:49:48,456
But this place is not just an insurance policy
625
00:49:48,472 --> 00:49:50,877
against the ultimate apocalypse.
626
00:49:51,219 --> 00:49:54,350
This is of huge value right now.
627
00:49:54,532 --> 00:49:56,202
For whatever we discover
628
00:49:56,203 --> 00:49:59,717
that a plant is teetering on the brink of extinction,
629
00:49:59,927 --> 00:50:04,084
we can now boost its numbers with seeds from here
630
00:50:04,150 --> 00:50:09,919
and so ensure that no plant species on earth need go extinct.
631
00:50:20,893 --> 00:50:22,601
There are an estimated
632
00:50:22,602 --> 00:50:26,522
400,000 different species of plant on the planet.
633
00:50:27,851 --> 00:50:32,403
We can't possibly understand the lives of each and every one of them.
634
00:50:34,863 --> 00:50:38,083
But here at the Royal Botanic Gardens in Kew,
635
00:50:38,241 --> 00:50:41,101
one of the birth places of scientific botany,
636
00:50:41,280 --> 00:50:45,227
we began to glimpse their extraordinary world.
637
00:50:49,869 --> 00:50:53,670
Kew is still in the forefront of botanical research
638
00:50:53,749 --> 00:50:57,314
helping to ensure that we not only understand plants,
639
00:50:57,367 --> 00:51:01,406
but protect them in all their astonishing variety.
640
00:51:07,784 --> 00:51:09,467
And here, we can see
641
00:51:09,494 --> 00:51:13,231
how plants in all habitats and environments
642
00:51:13,349 --> 00:51:16,478
are intricately connected with animals
643
00:51:18,333 --> 00:51:20,031
and with fungi.
644
00:51:21,345 --> 00:51:25,489
Not only do plants give the world much of its beauty,
645
00:51:26,277 --> 00:51:29,354
they are indeed the very basis
646
00:51:29,434 --> 00:51:32,342
of all life on earth.
50813
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