All language subtitles for 00019.track_4768

DAVID ATTENBOROUGH:
Plants cover

much of the land surface
of our planet.

But there is another
extraordinary green world

that is often hidden from us.

The world of freshwater.

It's one which presents plants

with huge challenges
for their survival.

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 Cafio Cristales 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 Cafio Cristales
is sometimes called

the most beautiful river
on Earth.

But when water levels fall,

plants like this
become vulnerable.

This is the Rio Roosevelt,
a remote region of the Amazon.

Here, exposed water plants
draw hungry visitors

from the surrounding forest.

Parrots.

They need minerals
that the plants

have extracted from the water

in order to come into
breeding condition.

(PARROTS CALL)

If the water drops further,

these plants
will dry out and die.

And so
where water levels fluctuate,

being rooted to the spot is not
always a plant's best strategy.

In Brazil,
during the wet season,

flooded rivers become
highways for travellers.

This water lettuce is not
anchored to the ground at all.

Its air-filled leaves help it

float along with the current.

It's not the only
traveller here.

Water hyacinths,
buoyed up by air bladders,

are also on the move.

Further downstream,

there will be new opportunities
for plants like these.

But the journey is hazardous.

Spider monkeys.

Their agility on thin branches

allows them to live where the
forest hangs over the water.

Passing plants are

a valuable addition
to their diet.

Only those that pass by
far from the bank are safe.

And the lucky ones
may reach the Pantanal,

the largest inland
water world on Earth.

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...

...and jostles 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.

But the losers in this war

do not go to waste.

These stranded water lettuce
break down and rot.

And as they do so,
they become a magnet

for swallowtail
and sulfur butterflies.

Every one of them is male.

Their reproductive organs
cannot mature

without essential salts.

The decaying plants

supply all they need.

The journey
of the water lettuce

may have
come to an end...

...but their influence will
continue in the form of

new generations of brilliantly
coloured butterflies.

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 headwaters
of the greatest of all rivers,

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 the 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 bladdervvort
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 bladdervvort 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 too has a hair trigger.

A lucky spider passes through.

The traps remain motionless,

waiting for something
that moves

with less care.

It attracts insects
by producing a sweet perfume,

just as a flower does.

A wasp has been lured
into the danger zone.

Distracted,
a mistake is inevitable.

A touch.

Nothing happens.

But the plant has remembered.

A single touch could be made
by a twig or a raindrop.

But another within 20 seconds
means prey.

The plant is still counting.

The trap has not fully closed.

Smaller prey, not worth
the effort of digesting,

can GSCGPG.

But for a bigger catch,

struggling seals their fate.

Five touches,
and the trap is clamped tight.

Digestive juices
flood the chamber,

and the victim is doomed.

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.

A chalk stream
in southern England,

and swaying in the current

is a plant for which
these rivers are famous.

It's called water crowfoot.

It's a kind of
aquatic buttercup.

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.

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.

But now, water-world plants

must ensure that
some of their seeds

will find suitable places

in which to germinate.

A river can provide transport,

but it's a one-wayjourney -

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

byjust 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.

Shallow seas, swamps,
rivers and lakes

are being damaged, drained
or even lost altogether

just as we are discovering

how essential they are
to the health of the planet.

The extraordinary plants
that live in our water worlds

are probably
the least noticed of all.

They're certainly
the least studied.

But the more you know about

the problems
of living in a water world,

the greater the wonder
of their success.

Surely they deserve
more of our attention

and, most importantly,

OUI' CGFG.