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(SNEEZES)

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The English summer
fills our landscape with lovely flowers,

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but it comes at a price - hay fever.

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For those of us who suffer from it,
and I certainly do,

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our eyes swell, nose runs and we get overcome
with fits of uncontrollable sneezing.

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The source of our affliction
is filling the air all around me - pollen grains.

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No bigger than specks of dust, they are
astonishingly varied and complex in shape.

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Each species of plant
has its own characteristic pattern.

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They're shed in millions from stamens
that tumble out of the grasses' tiny flowers.

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As the grains are released,
so the wind carries them away.

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It's these tiny particles,
when they get up our nostrils,

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that give so many of us such a bad time.

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But their proper destination, of course,
is not the human nose,

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it's structures like these,
the stigmas of other grass flowers.

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When a pollen grain carried by the wind
lands on one of these feathery traps,

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a grass plant is fertilised and can then produce
seeds which will grow into other grass plants.

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You might think such a method of distributing
pollen would be very wasteful and inefficient,

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but the fact remains that grasses
are extraordinarily successful.

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They've spread to every continent on earth,
and some of them have grown very big indeed.

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These, in Nepal, are the biggest of all,
standing twenty feet tall.

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Human beings, even rhinoceroses, could be
moving around in such mammoth meadows

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and still be totally concealed.

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Hazel, like many trees, also relies on the wind
to distribute its pollen.

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Because pollen is produced in vast quantities
and discharged wholesale,

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it and the structures from which it comes,
like these catkins, are regarded as male.

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The female structures, the stigmas,
grow separately on the hazel as tiny pink sprays.

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At the base of each stigma, there's a chamber
holding a few eggs - in hazel, only one.

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Although many pollen grains may fall on
a stigma, only one is needed to fertilise an egg.

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The grain develops a microscopic tube,
which grows down through the stigma

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and unites with the egg at the bottom.

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This then swells and becomes a hazelnut.

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Most plants, however, combine their male
and female structures into one flower.

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The stigma is usually in the centre, with the
pollen-producing stamens clustered around it.

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The petals are advertisements

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to attract animal messengers who will carry
the pollen from one flower to another.

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Many flowers, like this wild geranium,

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ripen their male and female structures
at different times, to prevent self-fertilisation.

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First, the stamens curl back and release pollen
from the containers at their tip.

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Only then does the white stigma open.

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Now it's ready to receive pollen
from another plant.

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The strange kangaroo-paw flower
from Western Australia

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produces its stamens in a line, like a comb,

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with the thinner, longer stigma
projecting in front of them.

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The flowers grow in a spike,
and open in succession

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to offer visiting animals a drink
of the sweet nectar that each holds in its depths.

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And when a honey-eater reaches down
with its beak to collect that nectar...

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..it gets pollen over the back of its neck.

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And then, when the bird goes to drink elsewhere,

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the stigma of the second plant
is brushed with the pollen from the first.

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In South America,
hummingbirds are the great nectar-drinkers.

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Flowers load them with pollen in similar ways.

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The stamens of this one
are clustered into a brush.

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And on goes the pollen.

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Many of these bird-pollinated flowers are red.
This is not just a coincidence.

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Unlike insects,
which are more sensitive to blue light,

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birds have a colour vision much like ours,

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and red draws their attention
as quickly as it draws ours.

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This South American plant, columnea,
at first sight has no bright colours at all.

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But look at its leaves from beneath.

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They have translucent blotches,

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and the light shining through them gives them
the scarlet brilliance of stained-glass windows.

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The flowers, close to the stem,
are pale, small and so easily overlooked.

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But hummingbirds have learned to recognise
that the leaf blotches are signposts.

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In some ways, this is an even better way
of advertising than using petals.

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The red patches are more economically produced,
they last longer than petals,

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and they will advertise
a whole succession of flowers.

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It's a good guess that a red,
robust, trumpet-shaped flower,

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no matter where you find it,
will be bird-pollinated.

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These aloes, for example, are in South Africa,
and this is a sunbird.

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There's another prediction you can make.

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Not only are prominent red flowers
likely to be pollinated by birds,

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but they're unlikely to have any scent.

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And this aloe hasn't.

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The reason why is obvious -

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birds, with very few exceptions,
lack a sense of smell.

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Perfume would be wasted on them.

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Colour is all they need to attract
their sharp-eyed, red-sensitive pollinators.

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This aloe, like many in the family, ripens
its stigmas at the same time as its stamens.

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So you might think the plant would be
in danger of fertilising itself.

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But aloes have a way of preventing that.

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Their stigmas can recognise their own pollen,

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and will only accept pollen from other plants.

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Proteas, another South African plant family,

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Iike aloes produce a multitude
of small flowers clustered together.

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But they pack them even more closely,

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so that several hundred tiny florets
form a single, spectacular bouquet.

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Those in the centre
may produce stamens and stigmas and nectar,

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while those around the outside are sterile
and serve only as advertisements.

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So proteas produce
spectacular flower-heads of great variety,

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and offer their pollinating birds
a large number of individual sips of nectar.

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But a few are different.

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This, too, is a protea,

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and although at first sight it might be
difficult to believe, it too is in full bloom.

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But the flowers are not perched
conspicuously on top, they're down here.

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They're brown, they point downwards
and in the evening they develop a yeasty smell.

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They're obviously not suited
for pollination by birds.

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But to discover what does pollinate them,
you have to watch them after dark.

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(CHIRPING OF INSECTS)

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A little bush mouse.

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The banquet won't last long,
for the flowers will soon be over.

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Then the mouse will go back
to its normal diet of seeds.

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But by that time, it will have carried pollen
from one plant to another, on its nose,

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which is all the protea requires
as payment for the meal.

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The durian tree of Borneo also blooms at night,

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and is also tended by nocturnal mammals...

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fruitbats.

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They rival birds
in their effectiveness as pollinators,

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for they too
will fly great distances in search of food.

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Mammals were the most recent group
in the animal kingdom to evolve.

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Before them, the reptiles ruled,

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and some of them, doubtless,
in the time of the dinosaurs,

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were conscripted by plants,
as some are still today.

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The giant gecko of New Zealand is one.

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The islands' only native mammals are bats,

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so plants have limited candidates
for the job of courier.

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The gecko has been recruited
by the pohutakawa tree.

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Dawn in Madagascar.

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Madagascar split away from the eastern flank
of Africa 40 million years ago,

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and it's been isolated ever since.

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Because of that, it has plants today
that are found nowhere else.

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The spectacular traveller's palm is one of them.

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It produces its flowers in sprays
between the leaves of its great fan.

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They're drab, stiff, almost leathery structures.

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You have to be pretty strong
to pull these hefty petals apart

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to reach the nectar they conceal.

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But the island not only has unique plants,
it has unique animals.

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Lemurs.

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They have all the strength that is necessary.

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There are many kinds of lemur,
but only a few have taken to nectar feeding.

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The black lemur is one.

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Its name is misleading, for though
the males are black, the females are brown.

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They have much longer tongues
than their relatives, nectar teetotallers,

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and that enables them
to drink from the palm's deep nectaries.

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Being dusted with pollen is only half the duties
the plant requires from the lemur.

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The other is to deliver the pollen
to another traveller's palm.

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The nearest may be miles away.

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But the lemurs move great distances.

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Having drained the nectar from one palm,
they set off to try and find another.

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Only when they've drunk
from a second traveller's palm

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will they have completed the task
given to them by the first.

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But the most widely-used messenger service

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is supplied neither by mammals,
birds nor reptiles, but by insects.

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In many ways, they provide the cheapest
and most efficient courier service of all.

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A plant like this Indian balsam

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can summon them with quite small,
economically-produced flowers.

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Each individual messenger,
such as this bumble-bee,

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will do its work
for quite a modest payment of nectar.

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And the balsam constructs its flowers

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in a way that ensures that no one gets a drink
without being given a load.

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It holds the nectar deep in the flower,
so the bee has to go right inside to get it.

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The stamens hang from the roof of the entrance,

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so that an arriving bee
brushes them with its back.

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When all the pollen has gone,

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the stamens loosen so that a departing
messenger knocks them off.

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And that exposes the stigma,

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so the next thirsty bee that arrives for a drink
will make not a collection but a delivery.

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Dozens of pollen grains
get caught on the sticky stigma,

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many more than are needed.

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And when the flower's function is over,
the petals fall.

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Then the egg chamber
at the base of each flower quickly swells

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and becomes a capsule full of seeds.

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Many plants have found that it pays
to have an exclusive courier service,

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so a messenger doesn't deliver
its package to the wrong address,

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a different kind of flower, where it'll be useless.

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This gentian, growing on the Cape
in South Africa, has adopted that policy.

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The reward it offers its employees
is edible pollen,

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and carpenter bees pack great quantities of it
into baskets on their legs.

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The stamens appear to offer yellow pollen
to all comers, but that is an illusion.

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These yellow structures are hollow tubes,
and the pollen is secure inside.

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A beetle attracted by the sight is totally baffled.

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So how do the bees manage to collect
such large loads of pollen?

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Well, if you listen very carefully
when one arrives, you can hear the answer.

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(BUZZING SOUND CHANGES)

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By vibrating more slowly than usual
and making a deeper buzz,

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the bee shakes the tube
with just the right frequency

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to make the pollen spurt out
of a tiny hole at the top.

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I can show you the sort of vibration
that's required with this tuning fork.

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There.

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You might think the long stigma
projecting to one side

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would collect pollen
sprayed around so extravagantly,

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but there's no danger
of the flower fertilising itself.

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The stigma doesn't become receptive
until all the flower's own pollen has gone.

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There's another advantage to this strategy.

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A bee can't tell by sight whether a yellow stamen
has pollen inside it or not.

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So those flowers with no pollen left
but newly receptive stigmas

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get a pollen delivery without having to pay for it.

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Honeysuckle rewards its employees
not with pollen but with nectar.

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It keeps the payments at the end of long tubes
formed by the petals,

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so a long tongue is needed to get it out.

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The hummingbird hawkmoth has one.

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To get the last drops, the moth has to probe
to the full length of its tongue,

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and that compels it
to brush the stamens with its underside.

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The flowers go on producing nectar well after
their stamens are exhausted and shrivel.

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So the moths go on drinking from them,

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00:21:42,560 --> 00:21:46,951
but now they brush pollen
off their undersides, onto the stigma.

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Some flowers make drinking
even more difficult for their couriers.

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This small iris grows in South Africa.

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Each flower has a hugely elongated tubular base.

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The tiny entrance to it is indicated
with exemplary clarity and accuracy

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by these white arrows on the petals.

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And here is the only tongue
that can reach that nectar.

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It belongs to a hoverfly.

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It's not so much a tongue as a fine tube,
but in proportion to body length,

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it's one of the longest
feeding implements in the animal kingdom.

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The clear markings are particularly important
because the tongue is so long

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that even in the lightest wind,
the end blows about.

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An extra thrust is needed to get the last drop.

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The iris only flowers for a few weeks,

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so what does the hoverfly collect
with its phenomenal tongue at other times?

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Well, after this iris is over,
this different blue flower opens.

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It's produced by another species of iris.

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There's a succession of plants
that bloom on the veldt in the next few months,

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so that the hoverfly is kept fed
throughout its short adult life.

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The hoverfly collects pollen on the front
of its broad head and on the back of its neck.

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00:23:43,640 --> 00:23:45,835
Butterflies, on the other hand,

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tend to accumulate it
around the base of the tongue.

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00:23:50,240 --> 00:23:55,234
They don't hold their tongue needle-straight
like the hoverfly - they curve it

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00:23:55,400 --> 00:24:00,679
and, sometimes, most remarkably,
they can put a sharp bend in it.

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This butterfly has got pollen not only
on its tongue but all over its legs as well.

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Pollen, however, is valuable stuff.

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In terms of calories,
it costs a lot for the plant to produce.

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00:24:23,200 --> 00:24:28,194
The crassula flower on which this South African
mountain pride butterfly is feeding

224
00:24:28,360 --> 00:24:34,469
releases its pollen so lavishly
that the butterfly gets it all over its tongue.

225
00:24:36,240 --> 00:24:39,755
The mountain pride
lives in the hills around the Cape.

226
00:24:39,920 --> 00:24:42,229
Several red flowers grow here,

227
00:24:42,400 --> 00:24:47,793
and the butterfly, unusually among insects,
has a particular liking for that colour,

228
00:24:47,960 --> 00:24:51,748
which elsewhere seems
almost the prerogative of birds.

229
00:24:55,600 --> 00:25:00,833
Not only are there red crassulas,
there are also red gladioli,

230
00:25:01,000 --> 00:25:06,358
and they too squander pollen
on the butterfly most lavishly.

231
00:25:06,520 --> 00:25:10,672
But there's one flower
that has done something about that

232
00:25:10,840 --> 00:25:15,118
and loads its pollen
onto the mountain pride butterfly

233
00:25:15,280 --> 00:25:18,670
in a much more accurate
and therefore economical way.

234
00:25:18,840 --> 00:25:22,799
And it grows at the head
of this spectacular gorge.

235
00:25:40,440 --> 00:25:43,557
And this is it, a red orchid.

236
00:25:43,720 --> 00:25:47,076
It's got a vessel at the back
which is full of nectar,

237
00:25:47,240 --> 00:25:50,755
and the butterfly knows exactly where it is.

238
00:25:53,200 --> 00:25:57,193
Orchids have a special way
of rationing their pollen.

239
00:25:57,360 --> 00:26:01,273
They parcel it up
into a pair of packets called pollinia.

240
00:26:01,440 --> 00:26:05,991
Here, they're hidden at the back,
behind those two white knobs at the top.

241
00:26:06,160 --> 00:26:08,958
The white lump at the bottom is the stigma.

242
00:26:15,520 --> 00:26:20,640
Like other orchids, this one
provides its visitors with a landing platform.

243
00:26:20,800 --> 00:26:26,591
There's only one position in which a butterfly
can stand in order to reach the nectar.

244
00:26:31,800 --> 00:26:35,509
As the mountain pride pushes forward
to get the last drop,

245
00:26:35,680 --> 00:26:39,798
a pad from one of those white knobs
is glued onto its back legs.

246
00:26:39,960 --> 00:26:45,592
And as the butterfly moves again,
it pulls out the yellow pollinia.

247
00:26:58,040 --> 00:27:03,353
When it visits its next flower,
it must once again alight on the landing platform

248
00:27:03,520 --> 00:27:05,476
in precisely the same position,

249
00:27:05,640 --> 00:27:10,191
and that now causes the pollinia
to be dragged across the stigma.

250
00:27:12,120 --> 00:27:14,680
That, too, is sticky.

251
00:27:17,040 --> 00:27:19,998
The orchid has been fertilised.

252
00:27:28,600 --> 00:27:30,636
Here in South Africa in spring,

253
00:27:30,840 --> 00:27:34,594
the veldt is covered
with as spectacular a display of flowers

254
00:27:34,760 --> 00:27:37,274
as can be found anywhere in the world.

255
00:27:37,440 --> 00:27:42,116
Some are advertising meals of pollen,
some drinks of nectar.

256
00:27:42,280 --> 00:27:45,397
And those aren't the only treats on offer.

257
00:27:47,240 --> 00:27:52,030
This flower, a relative of the snapdragon,
has a more unusual product,

258
00:27:52,200 --> 00:27:56,716
a nutritious oil, which it holds
at the end of two long spurs.

259
00:27:56,880 --> 00:28:01,874
Only one customer, this bee,
has the right equipment for collecting it.

260
00:28:04,960 --> 00:28:11,991
Its front legs are specially elongated and
thickly covered with hair which mops up the oil.

261
00:28:20,480 --> 00:28:26,430
In South America, a group of orchids offers
an even more unusual and sophisticated product.

262
00:28:26,600 --> 00:28:30,639
It, too, is an oil, but not an edible one.

263
00:28:33,840 --> 00:28:38,311
The customers for whom it's produced
are tiny iridescent bees.

264
00:28:38,480 --> 00:28:41,392
But only males visit the flowers.

265
00:28:42,040 --> 00:28:43,871
The oil is very waxy,

266
00:28:44,040 --> 00:28:47,919
and the bees have to scrape it
from a pad at the back of the flower.

267
00:28:53,000 --> 00:28:55,673
It's not a food, it's a perfume,

268
00:28:55,840 --> 00:29:00,470
and the male bees use it to attract females
during their courtship rituals.

269
00:29:00,640 --> 00:29:04,599
Each species of bee
needs its own exclusive brand,

270
00:29:04,760 --> 00:29:11,154
so each species of orchid tailors its product to
match the taste of its own particular customers.

271
00:29:19,920 --> 00:29:22,354
But it doesn't come for free.

272
00:29:30,720 --> 00:29:35,032
The surface of the orchid
around the oil pad is particularly slippery,

273
00:29:35,200 --> 00:29:38,954
and the males have a lot of trouble
keeping their foothold.

274
00:29:56,880 --> 00:30:01,908
One slip, and he falls down a chute
to collide with a sticky knob.

275
00:30:02,080 --> 00:30:06,437
It fastens onto him so securely that,
when at last he struggles free,

276
00:30:06,600 --> 00:30:10,354
he pulls the yellow pollinia away with him.

277
00:30:15,480 --> 00:30:20,270
Another orchid in this group imposes its will
on customers in a different way.

278
00:30:20,440 --> 00:30:22,749
That white rod is a trigger.

279
00:30:22,920 --> 00:30:26,754
Small bees are not heavy enough to operate it.

280
00:30:28,160 --> 00:30:31,630
But this one is altogether heftier.

281
00:30:33,640 --> 00:30:39,954
And in a fraction of a second,
the orchid dumps its cargo onto it.

282
00:31:00,920 --> 00:31:07,917
Some plants produce a reward that only
one animal seems to like, or could even reach.

283
00:31:08,080 --> 00:31:15,270
This tropical fig tree in northern Australia
has a relationship with a wasp that is so complex

284
00:31:15,440 --> 00:31:22,232
that it's very difficult to imagine who initiated it
or who is getting the better of the bargain.

285
00:31:22,400 --> 00:31:26,439
The fig tree carries its flowers
inside these small green knobs.

286
00:31:26,600 --> 00:31:28,670
They never see the light of day.

287
00:31:28,840 --> 00:31:33,709
The only way to reach them
is through this tiny hole in the centre.

288
00:31:38,840 --> 00:31:43,834
Within, the cavity is lined
by both male and female flowers.

289
00:31:44,000 --> 00:31:46,389
Each is little bigger than a pinhead.

290
00:31:46,560 --> 00:31:49,950
But some of the female ones
have been parasitised.

291
00:31:50,120 --> 00:31:54,557
Weeks ago, a minute female wasp
crawled in through the entrance hole

292
00:31:54,760 --> 00:31:57,672
and laid her eggs inside their ovaries.

293
00:31:57,840 --> 00:32:00,593
Now those eggs are about to hatch.

294
00:32:00,760 --> 00:32:06,517
First to emerge are male wasps,
but they're difficult to recognise as such,

295
00:32:06,680 --> 00:32:09,990
for they have long,
worm-like bodies and no wings.

296
00:32:10,160 --> 00:32:14,995
They will never fly,
they won't even leave this chamber.

297
00:32:25,920 --> 00:32:33,554
They're searching for those parasitised female
flowers that contain unhatched female wasps.

298
00:32:33,720 --> 00:32:40,319
A male, having found what he seeks, mates with
the female while she's still inside the tiny flower.

299
00:32:43,160 --> 00:32:47,711
He crawls away and will soon die.
His work is over.

300
00:32:50,320 --> 00:32:52,356
Now the females begin to hatch.

301
00:32:52,520 --> 00:32:54,875
They are more recognisable as wasps,

302
00:32:55,040 --> 00:33:00,433
for, although they are barely bigger than
mosquitoes, they do at least have wings.

303
00:33:10,400 --> 00:33:13,915
They head for the exit hole.

304
00:33:16,800 --> 00:33:20,759
To reach it, they have to pass
the fig's male flowers,

305
00:33:20,920 --> 00:33:24,196
and they get loaded with pollen as they go.

306
00:33:45,320 --> 00:33:50,348
Out into the open air they fly,
to look for another fig tree in flower.

307
00:33:50,520 --> 00:33:55,753
If they find it, they will force their way
into the little globular flower capsules

308
00:33:55,920 --> 00:33:57,956
and so fertilise the fig.

309
00:33:58,120 --> 00:34:02,398
Their reward for that service
will be to use the fig's flower chamber

310
00:34:02,560 --> 00:34:05,791
as a nursery for the next generation.

311
00:34:07,040 --> 00:34:12,239
Some plants, however, do not give
their pollinators any reward of any kind.

312
00:34:12,400 --> 00:34:15,392
In the warmer parts of Europe
lives a whole group

313
00:34:15,560 --> 00:34:21,157
that bamboozle their pollinators into thinking
they're going to get a sensational reward,

314
00:34:21,320 --> 00:34:23,788
a sexual one.

315
00:34:23,960 --> 00:34:27,999
They're little orchids,
and their flowers reproduce remarkably closely

316
00:34:28,160 --> 00:34:34,599
the signals that enable a male bee or wasp
to recognise a female of the same species.

317
00:34:38,440 --> 00:34:41,079
Several have blue patches.

318
00:34:41,240 --> 00:34:44,471
One is fringed with what looks like fur.

319
00:34:48,400 --> 00:34:52,029
A wasp's wings, in the right light,
do flash iridescent blue,

320
00:34:52,200 --> 00:34:55,590
and its abdomen is covered with thick brown fur.

321
00:34:58,000 --> 00:35:01,913
A female wasp also pumps out
an identifying perfume.

322
00:35:02,080 --> 00:35:06,278
But the orchid does the same,
and the result is irresistible.

323
00:35:14,120 --> 00:35:17,829
As the male wasp nuzzles forward
in his attempts to mate,

324
00:35:18,000 --> 00:35:22,835
he butts the pollinia,
which stick to him like yellow horns.

325
00:35:39,800 --> 00:35:43,349
He seems well aware
that something has happened to him,

326
00:35:43,520 --> 00:35:49,277
but there's nothing he can do about it,
and he flies off to try his luck elsewhere.

327
00:35:50,160 --> 00:35:52,390
Which is what the orchid requires,

328
00:35:52,560 --> 00:35:57,270
because this time he deposits the pollen
on another bogus female.

329
00:36:04,480 --> 00:36:10,077
The hairs on many such orchids run downwards,
as though the female is sitting head-up.

330
00:36:10,240 --> 00:36:13,471
But some reproduce her clinging head-down,

331
00:36:13,640 --> 00:36:17,349
and then the male must land that way
if he wants to mate.

332
00:36:17,520 --> 00:36:21,354
And he will get the pollen stuck to his rear.

333
00:36:27,600 --> 00:36:32,799
This one, too, seems fully aware
that he's got more than he bargained for.

334
00:36:38,920 --> 00:36:42,435
The orchid's mimicry
is so convincing and enticing

335
00:36:42,600 --> 00:36:48,118
that sometimes a flower will attract
a whole scrum of sex-crazed suitors.

336
00:36:49,680 --> 00:36:54,470
Some are trying to get to the orchid
and will inadvertently deliver the pollen.

337
00:36:54,640 --> 00:37:00,431
Other males, as there seems to be a full house,
attempt to mate with one another.

338
00:37:05,080 --> 00:37:07,594
In the heathlands of Western Australia,

339
00:37:07,760 --> 00:37:12,231
orchids perpetrate
an even more complex sexual charade.

340
00:37:12,400 --> 00:37:18,191
This time, the victims are a particular group
of wasps known as the thynnids.

341
00:37:20,120 --> 00:37:23,635
In spring, the female thynnid
emerges from the sandy soil

342
00:37:23,800 --> 00:37:26,439
where she's been feeding on beetle grubs.

343
00:37:26,600 --> 00:37:28,272
She's now ready to mate.

344
00:37:28,440 --> 00:37:34,470
If you burrow, it's difficult to develop wings,
and she has none, so she can't travel far.

345
00:37:34,640 --> 00:37:38,713
But the males can,
for they feed by hunting and do have wings.

346
00:37:38,880 --> 00:37:42,156
They will have to come to her.

347
00:37:52,400 --> 00:37:59,397
Once settled, she begins to emit a message
of perfume detectable a long way downwind.

348
00:37:59,560 --> 00:38:04,429
Then she waits, and usually not for long.

349
00:38:07,080 --> 00:38:11,596
The male carries her away
and will mate with her in mid-air.

350
00:38:17,320 --> 00:38:22,792
This, however, is plainly not, to our eyes,
a wingless female wasp,

351
00:38:22,960 --> 00:38:24,837
it's a tiny orchid.

352
00:38:25,000 --> 00:38:30,711
But it does carry the signals which indicate
"female wasp" to a male wasp.

353
00:38:30,880 --> 00:38:33,917
And not only that, it backs those visual signals

354
00:38:34,080 --> 00:38:38,358
with a perfume that is virtually identical,
chemically,

355
00:38:38,560 --> 00:38:41,711
to the smell emitted by a female wasp.

356
00:38:41,880 --> 00:38:48,592
And the two things between them
are quite enough to delude a poor male. Watch.

357
00:38:58,960 --> 00:39:01,520
He tries to fly away with her.

358
00:39:04,840 --> 00:39:07,149
But how is this helping the orchid?

359
00:39:07,320 --> 00:39:13,031
The answer lies in the ingenious
mechanical construction of the flower.

360
00:39:13,200 --> 00:39:16,749
The purple part is the bogus female.

361
00:39:16,920 --> 00:39:23,314
The other half has a little cup, with the pollinia
attached to another of those sticky pads.

362
00:39:23,480 --> 00:39:29,635
A black head and a furry body is all, apparently,
you need to disguise yourself as a female.

363
00:39:29,800 --> 00:39:36,638
This simplified mock-up is attached to the other
part of the flower by a delicate but strong hinge.

364
00:39:39,320 --> 00:39:43,279
When the male tries to carry off
what he assumes is the female,

365
00:39:43,440 --> 00:39:49,629
he's thrown upwards by the force of his own
exertions towards the cup and the pollinia.

366
00:40:04,240 --> 00:40:07,994
But the male's position
has to be absolutely correct.

367
00:40:08,160 --> 00:40:11,709
In spite of the enthusiasm
with which this one tries to mate,

368
00:40:11,880 --> 00:40:15,316
he isn't clinging in exactly the right way.

369
00:40:21,160 --> 00:40:24,835
Perhaps this time the orchid will be luckier.

370
00:40:28,280 --> 00:40:34,879
Obviously, there's little wrong with this orchid's
mimicry - two males are trying to get at it.

371
00:40:47,600 --> 00:40:51,832
There. The pollinia are attached to his back.

372
00:41:01,120 --> 00:41:05,352
But the most punishing
of fertilisation techniques used by plants

373
00:41:05,520 --> 00:41:11,629
involve not sexual deception but imprisonment,
penal servitude.

374
00:41:19,200 --> 00:41:23,352
Gull colonies in the Mediterranean,
as anywhere else in the world,

375
00:41:23,520 --> 00:41:26,353
are busy, noisy places, full of activity,

376
00:41:26,520 --> 00:41:30,877
as parent birds come and go,
tending their chicks.

377
00:41:38,480 --> 00:41:41,392
They're also messy, smelly places,

378
00:41:41,560 --> 00:41:48,033
with droppings, half-digested fish
and dead bodies lying about all over the place.

379
00:41:53,880 --> 00:41:58,476
In short, for flies and ants they are very heaven.

380
00:42:09,360 --> 00:42:14,718
And beside some gull colonies,
you may find one of these.

381
00:42:19,040 --> 00:42:22,794
This is not an image of a sexy,
seductive female animal.

382
00:42:22,960 --> 00:42:27,078
The mimicry is more gruesome.
This is a bogus corpse,

383
00:42:27,240 --> 00:42:32,633
mimicking rotting flesh covered with hair
and giving off the putrid smell of carrion.

384
00:42:32,800 --> 00:42:35,314
It's the dead horse arum.

385
00:42:35,480 --> 00:42:38,119
Blow-flies find this highly attractive.

386
00:42:38,280 --> 00:42:42,910
They need to find a hole to get into a corpse,
and this seems to be one.

387
00:42:43,960 --> 00:42:47,475
Within are a whole cluster of tiny flowers.

388
00:42:47,640 --> 00:42:51,758
Those at the top are male,
but they're not yet ripe.

389
00:42:51,920 --> 00:42:58,075
Below is a barricade of spines,
and below them, the female flowers.

390
00:43:17,120 --> 00:43:24,037
Some of the flies have already visited a flower
like this, and are carrying cargoes of pollen.

391
00:43:26,640 --> 00:43:28,551
Down here, in a real corpse,

392
00:43:28,720 --> 00:43:32,998
they might have found rotting flesh
on which to feast and lay eggs,

393
00:43:33,160 --> 00:43:37,756
so that later their maggots could also feed,
but they find nothing.

394
00:43:40,480 --> 00:43:45,110
As they continue to search,
pollen brushes off them onto the stigmas.

395
00:43:50,040 --> 00:43:52,793
The spikes discourage them from getting out.

396
00:43:52,960 --> 00:43:57,590
By now it's getting dark,
and flies don't fly at night. They're stuck.

397
00:43:57,760 --> 00:44:02,117
During the night, the male flowers
suddenly shed their pollen.

398
00:44:11,040 --> 00:44:15,670
And during the night, too,
the spikes of the barricade shrivel.

399
00:44:23,600 --> 00:44:27,593
So by the morning, the flies are free to go.

400
00:44:32,480 --> 00:44:37,315
And each takes with it a load of pollen
from the male flowers.

401
00:45:04,360 --> 00:45:07,875
One of the most extraordinary
of these insect-enticers

402
00:45:08,040 --> 00:45:12,318
Iives here in the tropical rainforest of Sumatra.

403
00:45:12,480 --> 00:45:15,916
It only flowers once in a thousand days,

404
00:45:16,080 --> 00:45:19,550
and when the flower develops,
it only lasts three days.

405
00:45:19,720 --> 00:45:25,795
So very few people have seen it, but here it is.

406
00:45:25,960 --> 00:45:30,397
Technically, it's a whole group of flowers
clustered around this,

407
00:45:30,560 --> 00:45:34,314
but you could be justified
in regarding it as one flower.

408
00:45:34,480 --> 00:45:39,679
And if you do that,
this is the biggest flower in the world.

409
00:45:39,840 --> 00:45:46,279
It's related to the dead horse arum,
but it's nine feet tall and three feet across.

410
00:45:46,440 --> 00:45:51,833
It's Amorphophallus titanum, the titan arum.

411
00:45:52,000 --> 00:45:56,596
The function of this great spike in the middle
is to produce a smell...

412
00:45:58,320 --> 00:46:02,996
..and if you smell it,
it smells very strongly of bad fish.

413
00:46:03,160 --> 00:46:05,720
This apparently attracts insects,

414
00:46:05,880 --> 00:46:09,998
which come along here
and go down into this great funnel

415
00:46:10,160 --> 00:46:13,436
to the small flowers that grow at the base.

416
00:46:15,800 --> 00:46:21,477
Until this film was taken, no one was sure
what insects pollinated the titan arum.

417
00:46:21,640 --> 00:46:26,714
As we watched, we saw that, without doubt,
the job was done by tiny sweat bees.

418
00:46:28,520 --> 00:46:32,149
Like other arums,
the male flowers form a band at the top.

419
00:46:37,200 --> 00:46:42,957
Below them, the female flowers,
with long, yellow-tipped stigmas.

420
00:46:47,040 --> 00:46:52,034
The bees seemed to find some reward
on the stigmas, for they crawled all over them,

421
00:46:52,200 --> 00:46:55,510
distributing the pollen
they had brought with them.

422
00:46:55,680 --> 00:46:59,673
But why should the titan arum
produce the biggest bloom in the world

423
00:46:59,840 --> 00:47:02,195
to attract such tiny pollinators?

424
00:47:02,360 --> 00:47:06,273
To be effective, these bees
must bring pollen from another bloom.

425
00:47:06,440 --> 00:47:09,989
But as the plant is rare
and only flowers once in three years,

426
00:47:10,160 --> 00:47:12,355
the nearest may be miles away.

427
00:47:12,520 --> 00:47:18,038
It's not easy to spread perfume over
such distances in the still air of the rainforest.

428
00:47:18,200 --> 00:47:22,830
Perhaps the best way is to disperse it
from the top of a towering spire,

429
00:47:23,000 --> 00:47:26,470
Iike smoke from a factory chimney.

430
00:47:31,640 --> 00:47:36,191
We tend to assume that flowers
are here to gladden our hearts.

431
00:47:36,360 --> 00:47:38,157
They're not, of course.

432
00:47:38,320 --> 00:47:41,949
Plants produced flowers
long before humanity appeared,

433
00:47:42,120 --> 00:47:46,159
to summon mammals, birds,
and, above all, insects.

434
00:47:46,320 --> 00:47:50,029
And though they sometimes
are given some payment,

435
00:47:50,200 --> 00:47:52,031
they are the servants.

436
00:47:52,200 --> 00:47:56,637
The masters are the plants.

437
00:47:57,305 --> 00:48:03,604
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