Original subtitles

David Attenborough: Plants cover

much of the land sun'ace of our planet.

But there is another extraordinary green world

that is often hidden from us.

It's one where plants have overcome huge challenges

in order to survive.

The world of freshwater.

At first sight,

a lake like this would seem to have

everything that life needs in order to thrive -

clear, oxygen-rich water,

plenty of dissolved nutrients and minerals

and lots of sunlight.

But in fact, life in freshwater

presents plants with huge problems.

To succeed, plants have had to abandon

many of the adaptations

that have served them so well on land

and evolve something quite new.

And in doing that,

they have created some of the most beautiful

and bizarre and important habitats on earth.

There are few places where it's more difficult

to make a permanent home

than a freshwater torrent like this one.

Violent currents rip across the riverbed,

scouring it clean...

Ripping land plants from their margins...

And drowning them.

How could any plant survive in a place like this?

Yet even here, some do manage to, quite literally, hold on.

They can grasp the bare rock with remarkable strength.

This ability allows plants to thrive

in these otherwise hostile environments.

This is the cano crista/es river

in Colombia.

These plants are red macarenia,

sometimes called the orchid of the falls.

They cling to the riverbed not with their roots

but with their stems,

glued to the rock surface

by one of the most powerful adhesives in nature.

The rock itself will break

before these anchors lose their grip.

These feathery filaments are their modified leaves,

and they do what roots normally do -

gather the minerals and nutrients they need

that are dissolved in the water.

With such spectacular colours,

it's hardly surprising

that the cano crista/es is sometimes called

the most beautiful river on earth.

But being rooted to the spot

is not always the best strategy

for living in a water world.

This is a water lettuce,

and it has some remarkable adaptations.

Its roots hang freely.

So it's not anchored to the ground.

And its leaves are thick and spongy

and covered in fine hairs,

so the plant itself is, more or less, unsinkable.

This combination of characteristics

enable the water lettuce to do something

that almost no land plant can do -

it can travel.

It is an ability that becomes invaluable

when, during the wet season,

flooded rivers become great highways,

as they do here, in South America.

This is the largest inland water world on earth,

the pantanal.

For a few months every year,

it provides water plants with ideal conditions.

But all too soon,

it becomes a battleground.

Plants are racing to claim their space on the surface.

The water lettuce rapidly expands

its network of hanging roots

so that it starts absorbing nutrients

before other competitors arrive.

Water hyacinth appears.

Its leaves are carried on stalks

filled with air

that also make it virtually unsinkable.

The race for space intensifies.

A new competitor arrives - ludwigia.

It spreads by developing a chain of tiny rafts...

Andjostles for space

with the densely packed leaves of mosaic plants.

All are racing to claim as much sunlight as possible.

They flower quickly, before the floodwaters recede.

And these surface dwellers also have competitors.

Including one that has been waiting

in the depths...

And is now stirring.

It's a monster.

It's well armed.

It clears space for itself...

By wielding one of its buds...

Like a club.

And now...

It dominates the surface.

This is a leaf of the giant waterlily.

It expands by over 20 centimetres a day

and eventually measures more than two metres across.

Its immense leaves are supported

by a network of air-filled struts

and protected by spines two centimetres long.

The leaves float high in the water,

and their surfaces are dotted with tiny holes - drains -

that help them ensure

that rainwater doesn't accumulate and sink them.

Nutrients from the fertile mud below

are carried up by tubes in its stem

to fuel the leaf's expansion.

Over the next few months,

the Lily will produce some 40 or so

of these gigantic leaves.

And as each one reaches the surface and expands,

more and more light is taken

from those plants

that are trying to grow beneath.

Competitors are pushed aside.

Some are crushed...

Or skewered.

Eventually, its immense leaves press their margins

against one another,

totally cutting off the light from the plants beneath them.

The battle is over...

And victory is total.

The frozen water world of lake akan,

in northern Japan.

Home to one of the strangest and most primitive of plants.

It's an alga,

like those that appear so mysteriously in our ponds.

But this one is truly extraordinary.

Each spring, the melting ice releases

soft, velvety balls of interwoven threads

called marimos.

This one is small, no bigger than a walnut.

But there are lots of them here.

They attract the attention of visiting whooper swans.

But there is one way for the marimo to escape

from the danger,

and it depends on a change in the weather.

Fortunately, in the spring,

winds sweep across the lake...

Creating currents that carry some of the marimos

beyond the reach of hungry swans.

It's the start of a remarkable journey.

They are gently carried back and forth

by the currents

so that the marimos become more and more spherical.

And slowly, they travel into deeper water.

Here, there are great numbers of them,

certainly many millions.

Some are the size of basketballs.

They are safe from swans

and the water is still shallow enough

for some sunlight to reach them.

It seems a perfect home.

And so it is.

Almost.

The snag is that these waters also carry a fine sediment

that can clog the marimos' surface,

cutting off the all-important light.

But the marimos are not entirely immobile.

They dance.

The winds blowing over the lake's surface

create currents beneath

that are sufficiently strong to move the marimos.

They rub against each other.

And, in just a couple of hours of gentle movement,

they're all clean once more.

As they spin,

every part of their surface

gets enough time in the sunlight

to keep growing.

This is the heart of the Amazon.

There are water worlds here that are so remote

that, even today, few people have ever seen them.

This barely explored tributary

is rio claro.

And here,

when conditions are just right,

it's possible to witness

a rare and remarkable spectacle.

The river is so crystal clear

that its bed is bathed in sunlight.

A magical landscape of miniature mountains

and valleys.

It's carpeted by pipewort,

fanwort and star grasses.

As the sun climbs in the sky...

Bubbles of gas appear.

Evidence of photosynthesis.

Deep inside the plant cells,

tiny structures called chloroplasts

move towards the light.

They absorb carbon dioxide

and use the sun's power to synthesise the sugars

that the plant needs to grow.

And, as a by-product, they release oxygen...

The gas that we

and all other animals

must have in order to breathe.

Now, in late afternoon,

bubbles of oxygen make the river water fizz

like champagne.

The plants can become so buoyant with gas

that they rise to the surface...

Even carrying the bedrock with them.

Only in this remote water world

can this spectacular natural wonder be seen.

Eastern Venezuela.

Here, rectangular table mountains known as tepui

stand above the tropical forest.

There are more than 50 such

isolated mountain plateaus here,

each home to a unique community of plants.

Downpours are so torrential that no soil can accumulate

on their broad, rocky summits,

and some plants living up here

have to find their nutrients from another source.

These are bromeliads.

Their leaves are shaped like a funnel

and collect rainwater,

which accumulates in the centre.

This small pond is colonised by all kinds of tiny animals.

And it is their bodies, when they die,

that provide some of the nutrients

the bromeliads need.

This makes a good partnership,

in which both parties can thrive.

But it can be exploited...

By a plant predator.

This probing stem

belongs to a plant called a bladderwort.

It too is in need of nutrients.

And a well-stocked bromeliad pool

is just the place to find them.

This one is full of aquatic animals.

The bladderwort begins to change...

Into a hunter.

It develops bladders

and removes sufficient of the water within them

to create a partial vacuum.

Each bladder has a trap door beside it with trigger hairs.

And now all the bladderwort has to do...

Is to bide its time.

It only takes one touch

for the trap door to snap open...

And suck in its prey.

It's all over in a millisecond.

And after it has fed,

a bladderwort has enough energy

to produce another tendril,

to search for another bromeliad pool.

Swamps and bogs are also poor in nutrients.

So several plants that live in such places

catch insects too,

if they can.

The leaves of sundews

are covered with long red hairs,

each tipped with a droplet.

These glistening globules are in fact glue.

Once the sundews detect

the taste of their victim's body...

They flood it with digestive enzymes.

The little body disintegrates.

And the sundew gets the nutrients it needs.

Another plant has an even more elaborate way

of catching a meal.

The Venus flytrap has leaves

that are lined with interlocking teeth.

It attracts insects by producing a sweet perfume,

just as a flower does.

It too has a hair trigger.

And another insect is caught.

But the technique is more complex

than it might seem.

The Venus flytrap has a problem.

It needs to avoid false alarms -

snapping shut on something inedible,

like a raindrop or a little bit of twig.

That would be a waste of both time and energy.

So how does it avoid that?

Well, it does it by counting.

If I touch this one sensitive hair just there...

No reaction.

That could be a false alarm.

But the plant remembers that for 20 seconds.

And if I touch it a second time within that time...

Then that's much more likely to be worth eating.

It closes!

So far, so good.

But now it needs to be absolutely certain

that it's got something worth eating,

so it continues counting.

Only after it has totted up five separate touches

to those hairs

will it give the final squeeze

and then begin to produce the liquid

from the surface of the leaf

which will dissolve the body of its unfortunate victim.

The flytrap now has enough energy

to produce flowers

and attract pollinating insects.

Wind and insects, between them,

pollinate virtually all land plants.

But neither method can be used

by plants that live entirely underwater,

so some lead double lives.

At York stream, in southern england,

and swaying in the current

is a plant for which these rivers are famous.

This is water crowfoot, a kind of aquatic buttercup.

For most of the year, it is underwater.

And if I take this underwater camera...

You can see its floppy stems grow horizontally.

That reduces the risk

of being swept away by the current.

But each spring, when it's time to flower,

it produces something crucially different.

A stem that is stiff enough to resist the current...

And lift its flowers into the air above.

And now, of course, they can get help from insects.

So, every year, in part at least,

water crowfoot becomes a land plant...

And provides us

with one of the loveliest natural spectacles

of the early English summer.

Water crowfoot is not the only water plant

to lift its flowers above the surface.

Plants do so all around the world.

From the swamps of the pantanal...

To the lakes of Thailand...

They all burst into spectacular bloom.

Once they've been pollinated, they produce seeds.

And now their flowers have done their job,

some return to a life...

Underwater.

Now they must ensure

that some of their seeds

will find suitable places in which to germinate.

Bulrushes, every year,

produce these long, brown, velvety objects.

Look what happens when I break one open.

It contains almost a quarter of a million seeds.

Each seed is attached to a delicate parachute.

Even the slightest breeze will lift it

and may carry it for very long distances indeed.

So even though suitable stretches of freshwater

are few and far between,

there's a good chance that at least one

will end up in a place where it can grow.

Much bigger seeds, of course, can't travel by air.

A river can provide transport,

but it's a one-way journey -

downstream -

that often ends up in the sea.

And that's not ideal.

So how can any riverside plant avoid this

and travel upstream?

Here, along the bonito river, in Brazil,

a variety of trees manage to do exactly that.

They embed their seeds

in the middle of soft, sweet fruit.

Monkeys, such as these capuchins...

Make a meal of them just as soon as they're ripe.

But monkeys are very wasteful feeders.

And what's not eaten...

Ends up in the river and is washed away.

But not all.

In the fruiting season,

hundreds of piraputanga fish

gather beneath these trees.

But the piraputanga want more than the monkeys' leftovers.

The brightly coloured fruits are clearly visible,

even to the fish in the water below.

And some manage to claim them

even before a monkey does.

This isn't a skill mastered

by just one particularly successful acrobatic fish.

Many of the piraputanga can do this.

Nor is this a disaster for the tree.

Far from it.

These piraputanga are migratory,

heading many miles upriver to spawn.

The trees, by enticing the fish to eat their fruits,

have a perfect means of transport for their seeds.

With luck, the seeds will be deposited

many miles upstream.

The ability to colonise new habitats

has allowed one group of flowering plants

to venture out of freshwater

and into a world that may look the same to us...

But for a plant is crucially different.

The much greater, saltier world -

the sea.

This is a fruit from one of the most important plants

on the earth today.

Sea grass.

This particular one is floating off the coast of formentera,

in the mediterranean.

100,000 years ago,

a sea grass seed like this

sank to the sea floor just here.

And eventually, it produced...

A great Meadow.

A Meadow that is still flourishing today.

It did so by cloning itself.

Now over ten miles across,

it's not only one of the largest

living organisms on earth...

It's also one of the oldest.

And it supports a rich community

of many kinds of animals.

It's become a kind of marine Savanna.

Over a thousand species now live here.

Some, like these elegantly camouflaged pipefish,

live nowhere else but amongst the sea grass.

Sea grass fringes many of the world's coasts.

Turtles depend upon it, too.

And so do dugong,

animals that are sometimes called,

very appropriately, sea cows.

Today, sea grass plays a critical role

in maintaining the health of our planet.

It creates stores of carbon around its roots

at an enormous rate -

35 times faster, in fact,

than plants that live on the floor

of a tropical rainforest.

Here, off formentera,

it's possible to see beneath the living sea grass

layer upon layer of trapped carbon

that the plants have accumulated

over the past 2,000 years.

Sea grass, however, is easily destroyed by human disturbance.

A third of the world's underwater meadows

have already been lost,

and many more are in decline.

Biologists are now striving

to not only protect the remaining meadows

but to restore them.

One plant at a time.

Sea grass could be a valuable ally

in our fight against climate change.

Today, water worlds everywhere are under threat.

Many of their inhabitants are disappearing

without us even being aware of their existence.

The plants that grow in water

are probably the least noticeable.

They're certainly the least studied.

But the more you know

about the problems of living in that way,

the greater the wonder of their success.

Surely, they deserve more of our attention

and, most importantly, our care.

This vast wetland is the pantanal.

The water worlds team

are heading to a plant battlefield -

the home of Brazil's giant waterlily.

This is like seeing the end of a war -

there are leaves growing on top of each other,

flowers going through leaves... Unbelievable.

To capture this story in all its detail

would take over a year

and require a unique green planet approach,

both filming here

and in a parallel mini pantanal,

in deepest, darkest...

Devon.

This is the unique world

of specialist time-lapse cameraman Tim Shepherd.

Tim has the reputation

of being able to think like a plant.

It's absolutely crucial

that you get the plant really happy.

And to make the giant Lily feel totally at home,

Tim must build a little piece of Brazilian wetland.

First, a 10, 000-litre tank.

Hundreds of bricks,

almost a thousand kilos of soil

and countless cups of tea later,

the foundations are complete.

So far, so good.

Now time to prepare

for the new green planet camera system.

That way.

We're trying to assemble the main gantry framework

so that we can mount the moving rig on top of it.

So it's a bit of a fiddle to get all the screws

in all the right places, basically.

After a few weeks,

the building works are complete.

The flood can now begin.

Tim needs to be sure everything in the room

is heated to tropical temperatures...

Ah!

Before the star of the scene can move in.

Carefully grown at the royal botanic gardens

at kew, especially for us.

Everything depends on this one plant.

There will be no time for a second attempt.

And even more important for Tim,

to keep his guest happy and healthy.

This big monster needs a lot of feeding.

We've found we need about five sandbags

full of compost every two or three weeks.

So we just sort of lower them in

and stick them down by the roots.

Whoa! There we go.

Whilst the Devon giant settles in...

The pantanal crew

are continuing to get their shots.

Time to see

some giant waterlilies underwater,

and I hope there's no anaconda.

Oof!

Mission accomplished.

The pressure is now on Tim.

After months of pampering,

the giant Lily is ready for action.

First thing to film is a leaf spike rising up

from the depths.

Luckily, there are no anacondas here.

The special camera weighs over 40 kg.

It's suddenly become less heavy, which is good.

The new rig

means Tim will be able to follow

the emerging plant in any direction.

Whoa! Fancy!

(Laughs)

The technology is working well,

but nature is starting to derail Tim's plans.

Getting really tangled up with all these weeds!

What happens is, we've got

a bit of an ecosystem developing here.

Before you know it, you get masses and masses

of algae growing in amongst it all.

Eugh!

Gah!

I think I've just released some anaerobic gases there.

No, not me, the...

The algae.

State-of-the-art tools help keep the algae at bay.

Eugh!

Just in time for Tim to film liftoff.

Well, that's quite nice, coming out of the water.

Look at that!

Tim's focus can now shift

to the battle that's starting to take place on the surface.

Well, I'm trying to film

this new bud coming out on this Lily leaf.

It's going to take about three days

to grow from where it is now

to somewhere in this zone, between these two other leaves.

I want that to last about ten seconds.

Ten seconds is about 250 frames.

That works out to about one frame every 20 minutes.

But plants don't read scripts.

It's nature - it doesn't always do

what you think it's going to do.

We've had a few false starts,

where the leaf has swung out of shot and gone somewhere else.

Or it just grows a lot quicker than you thought.

It's a challenge to get things right,

but with the combination of Tim's expertise

and the new camera system,

results are starting to look good.

I think the difference now with this series

is we can bring the plants much more to life

as characters

and tell their story in a much more dynamic way.

It's great to be able to follow them around,

much more in the way you'd film an animal behaving.

These rigs have given us

a whole new realm of possibilities.

After over a year of filming and recording

100, 000 separate images,

the secret life of the giant waterlily

and the battle of the pantanal has been revealed.