October 28, 2025 • 34 mins
The Millennium Seed Bank holds over 2.5 billion seeds – but where do they all come from, and how do they end up in those deep underground vaults?
In this episode of Unearthed: The need for seeds, Cate Blanchett joins UK Seed Conservation Coordinator Ted Chapman and UK Conservation Projects Officer Isabel Negri on a seed-collecting mission in the South of England. Searching for yellow rattle, she learns how scientists balance collecting enough for research while leaving nature undisturbed.
Seeds also arrive from across the globe. Nattanit Yiamthaisong, a PhD student, shares how her research at the MSB is helping her understand how temperature affects germination — skills she’ll take back to her forest restoration work at Chiang Mai University.
Back at Wakehurst, Seed Curator Sian McCabe guides Cate through the labs where seeds are dried, cleaned, and x-rayed before being sealed deep in the vaults — the beating heart of this global effort to protect plant life for generations to come.
You can support the vital work of the Millennium Seed Bank by donating here: www.kew.org/seeds
Unearthed - The need for seeds is a Fresh Air production for the Royal Botanic Gardens, Kew.
Series Producer: Hannah Fisher, Executive Producer: Annie Day, Director of Content: Michaela Hallam. Sound Design by Dan King.
With special thanks to everyone at Wakehurst and the Millennium Seed bank who helped with the production behind the scenes.
See omnystudio.com/listener for privacy information.
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Cate Blanchett (00:00):
You really are on the edge of South Downs. Could
(00:04):
you describe it as a natural landscape or...
Ted Chapman (00:06):
So, the landscape we're driving through now is not really
natural. No. So, these fields are arable fields, so they
would normally be gray cereals, but for this year, at
least they've been sown with it looks like some kind
of wild seed mix.
Cate Blanchett (00:20):
I'm in a Jeep lurching over a dusty single track
road where deep in the South Downs National Park, which
is just beyond Brighton on England's southern coast.
Ted Chapman (00:31):
Skylarks are taking advantage of that because they nest in
the ground. So, they're probably nesting.
Cate Blanchett (00:34):
You can hear them outside. That's Ted Chapman behind the
Wheel UK Conservation Partnerships Coordinator at Kew's Millennium Seed Bank
at Wakehurst. He's also my guide for today.
Ted Chapman (00:46):
So, these hills that we're driving over now are all
chalk, and the chalk is really close to the surface.
So, the soil here is only 10 or 20 centimeters deep and
that very chalky soil, very low fertility, very sharply drained,
it drains really quickly. That's really what informs the type
of vegetation that we have, and that's what makes this
(01:10):
habitat special because these types of soil conditions and rock
conditions are not found very commonly.
Cate Blanchett (01:18):
We're heading to Castle Hill National Nature Reserve, which is
looked after by Natural England, and I'm joining Ted and
his team to collect wild seeds. Is this somewhere where
you'd come see collecting a lot? Is this an annual pilgrimage?
Ted Chapman (01:33):
So, we've collected a lot of seed in Castle Hill
in sites like this, because the chalk grassland supports an
exceptionally diverse flora, and many of those species are highly
specialized and quite rare. So, because we're often targeting threatened
species, we're often found in places like this.
Cate Blanchett (01:59):
The MSB's central mission is to gather wild seeds from
across the globe, preserving them to safeguard the future of
our planet. This work focuses on species under threat around
the world, often found in far- flung countries. However, you
might be surprised to know that some of the species
most in need of protection are much closer to home.
(02:21):
It's just magnificent. It's so wide and open and there's a big smudge
of red down there though poppies.
Ted Chapman (02:28):
Yeah, we're going to get a close- up view of
these beautiful poppies.
Cate Blanchett (02:31):
But just as important as place is time. In seed
collecting, timing is everything. What we're hoping for today is that
our visit coincides with the precise moment the seeds are
ready to be gathered, so that we can follow their
journey as they're carefully processed and then stored for safekeeping
(02:54):
in the vaults of the Millennium Seed Bank at Wakehurst.
I am Cate Blanchett, Kew's ambassador for Wakehurst, and this
is Unearthed
Ted Chapman (03:12):
So, we need to get through this gate.
Cate Blanchett (03:14):
Yeah, I can do it. It's the gate etiquette. You
learn that in Australia very quickly. Oh, I see those
two bars there.
Ted Chapman (03:24):
So, the last thing we want is off- road bikes, off-
road vehicles coming into the reserve and destroying the habitat,
which would just happen so easily. You can imagine these
habitats takes centuries or millennia to evolve, but only seconds
to destroy.
Cate Blanchett (03:38):
Yes, yeah. Gosh, there's this team flowers, isn't it?
Ted Chapman (03:41):
Yeah.
Cate Blanchett (03:44):
They're heavy.
Ted Chapman (03:44):
They are heavier. Are you okay with that? And then you twist it at the top. That's
it. Oh, great. Okay.
Cate Blanchett (03:55):
Here we go.
Ted Chapman (03:55):
Okay. In we go.
Cate Blanchett (04:03):
We pass through multiple gates and descend into a valley.
It's wildly overgrown with shrubs and vegetation encroaching on the
track. And then as we lurch around a corner, the
tree's clear and I'm greeted with the most beautiful vista.
Oh my goodness, this is magnificent. It looks so ancient
(04:24):
because the hills are just given away to a flat
plane. It's got a smattering of poppies. And what's the
yellow? Is that this grass... Man, it's so beautiful. It's
almost like someone's taken a brush with a thousand colours.
Ted Chapman (04:39):
Yes, yeah. So, the reserve is on these steep hillsides
and then at the bottom of the valley, we've got
this flatter area with deeper soils. And then we've got
this wash of poppies. So, beautiful.
Cate Blanchett (04:50):
Something out of The Wizard of Oz. So, if you find
me asleep in there, rescue me.
Ted Chapman (04:57):
So, the slope ahead of us is where we're going
to be doing our harvesting today. And this is Castle
Hill itself.
Cate Blanchett (05:02):
You mean the green quite vertiginous- looking slope ahead of
us that's got the...
Ted Chapman (05:07):
Exactly. So, we can see-
Cate Blanchett (05:08):
The strawberry on the top.
Ted Chapman (05:08):
... we've got the scrub at the top. We've got
this arable field at the bottom. We've got this slightly
flatter, rough bit in between. And that area was ploughed
in the second world war. And that's why even now,
it's still very different to the ancient short grassland, which
is on the steep slope.
Cate Blanchett (05:29):
And what was attempted to be grown there?
Ted Chapman (05:32):
That would've been crops for eating in that dig for
victory effort. So, these soils are with chemical fertilizers, they're
quite amenable to growing things like cereals, wheat, barley, flax.
Now that farming ceased some decades ago, but even with
decades of very careful management, you can see the grassland
at the bottom of the slope is very different to
the grasslands on the sides.
Cate Blanchett (05:53):
It's really green and tufty.
Ted Chapman (05:55):
Yeah. So, that is good, but we don't want too
much of that. We need a good balance.
Cate Blanchett (06:01):
So, what makes this spot so special apart from its
incredible beauty?
Ted Chapman (06:06):
It's really the quality of the chalk grassland. So, we're
going to be in one of the nicest patches in
just a second. You'll see the diversity of species and they're
all tiny weeny because it's so infertile, but there are
many, many species packed in. So, we can record 40
or more species in a square metre here. So, this
is one of the most plant- diverse habitats in Western
(06:27):
Europe on this small scale. So, it's really special floristically
and it's of course the vegetation then supports the butterflies,
the other invertebrates, the birds that are associated with the
invertebrates and so forth. So, that's really why this is
such a special place.
Cate Blanchett (06:44):
After a quick safety briefing from Ted and his colleague,
Isabel Negri, UK Conservation projects officer at the MSB, we start
to clamber up the hill. We wade through some tall
grasses at the bottom, but they soon thin out. There's
so many varieties of plants and I'm sure a myriad
of insects all thriving underneath my feet.
Ted Chapman (07:07):
We try to tread lightly in habitats like this where
we can. So, we've got into the chalk grassland. It's
very low.
Cate Blanchett (07:17):
And not as dense.
Ted Chapman (07:18):
Much, much less dense. And if you start looking into
the sword, you can see there are lots of different species, different
grasses, different species, and they're all little thistle there, a little bedstraw
there, all growing intermeshed, one with another. And underneath, you can
see it now looking very dry and droughty this grey soil.
(07:40):
That's the very chalky alkaline soil. So, this site is
grazed by cattle. Grazing is essential because without the grazing
this would revert through scrub to woodland and the grassland
would be lost. So, that sustained grazing at the right
level over centuries and centuries is what has created and
maintained this landscape.
Cate Blanchett (07:59):
As Ted started pointing out different plants, I began to
think I was getting rather good at spotting unusual species.
I should work at the MSB.
Ted Chapman (08:07):
Let's head up. We'll find... There's always so much to see.
Cate Blanchett (08:12):
Yes. It's hard not to get waylaid.
Ted Chapman (08:14):
Yeah.
Cate Blanchett (08:14):
What's that little?
Ted Chapman (08:17):
That is rabbit poo.
Cate Blanchett (08:19):
Oh, great. I might put that in my pocket
Ted Chapman (08:21):
So, we don't aim to collect that.
Cate Blanchett (08:23):
We can use it later. Chocolate covered rabbit poo. Here I
was, thinking I'd found a rare seed rabbit poo. Clearly,
I'm not going to get a job at Wakehurst. After
my identification of the rabbit poo, we continued up the
hill making our way towards some orange markers.
Ted Chapman (08:45):
So, these markers mark out where we've got a really lovely
population of yellow rattle. So, yellow rattle is what we've
come here to collect today.
Cate Blanchett (08:55):
And what's so important about the yellow rattle?
Ted Chapman (08:58):
So, yellow rattle is a semi- parasitic species. So, that
means it produces its own food, but it also parasitizes
other species growing with it. And that means it reduces
their vigor. And that makes it quite important in this
habitat, because it helps balance the really vigorous species against
the more delicate species and allows those more delicate species
(09:19):
to thrive. So, it's really very important for the kind
of function of the plants growing here.
Cate Blanchett (09:24):
It's a regulator.
Ted Chapman (09:25):
It's a regulator, like a community engineer almost. It's found
in a lot of grassland sites. We specifically need to
collect it now because we've used quite a lot of
the collection that we have for research work that we've
done looking at the germination needs of this species. So,
yellow rattle is actually a species which has a very
(09:46):
narrow temperature window in which it can germinate. And so,
we've done some work and Isabel has been involved in
this to work out exactly what the minimum and maximum
temperature range that yellow rattle needs. And then we model
that against climate change. So, we think in 50 years'
time, will the climate still provide the conditions that yellow
rattle and other species need to germinate? So, many species
(10:09):
are resilient and they will be able to regenerate successfully
in a warm climate. But yellow rattle is an example
of a species which is quite vulnerable, because it needs
cold winter conditions to break dormancy and germinate. So, it's
important to understand that and start thinking about how we
can manage grasslands and restoration projects to counter that and
(10:31):
build adaptation and make sure this particularly important species survives.
So, we've used seed to support that research, so we
need to replenish that seed in the seed bank. So, we've got it
for next time. So, the first thing we're going to
do is find similar rattle and take a look at
it. Some specimens here.
Cate Blanchett (10:50):
It's got a sort of a reddish brown stem with almost like
two little pods, green pods.
Ted Chapman (10:57):
That's right. Yeah. Will it rattle? That's the seed rattling
around and that's how it gets its name.
Cate Blanchett (11:06):
So, you want to collect them when they're dried?
Ted Chapman (11:08):
Exactly right. So, we want to collect seed at the
point of natural dispersal. So, that's when it's being dispersed
into the environment. That's when it's mature, it's when its
longevity. So, the amount of time it will be able to
survive in the seed bank is at its greatest.
Cate Blanchett (11:22):
It struck me as almost paradoxical that we were gathering
seeds from the very habitat where I just learned how
vital they are as nature's own community engineers. But Ted
and his team work by a clear principle. You never
take more than 20% of the seeds in the field.
Each of the pods are filled with tiny seeds. And
(11:43):
so, our collection begins with some counting.
Ted Chapman (11:50):
Okay, I make that 25 in my patch.
Cate Blanchett (11:55):
There's quite a lot here actually.
Isabel Negri (11:57):
How many did you find?
Cate Blanchett (11:58):
I think about between 35 and 40 in a square meter.
Isabel Negri (12:02):
Oh.
Ted Chapman (12:02):
Okay. Yeah, we average at about 20 plants per square meter.
Cate Blanchett (12:09):
And a little bit of maths.
Ted Chapman (12:11):
I've crunched the numbers and I can tell you that
we have approximately 1. 4 million seeds in our sampling
area here of yellow rattle.
Cate Blanchett (12:19):
Yeah, down.
Ted Chapman (12:20):
There's always tonnes more seed than you think there is.
Cate Blanchett (12:22):
And just before we start collecting, there's one more important step.
Ted Chapman (12:26):
If you've got some seed in your hand, Isabel-
Isabel Negri (12:28):
Yes.
Ted Chapman (12:28):
... shall we see if we can do a cut test?
Isabel Negri (12:33):
Yeah. I'll pass it to Kate. There you go.
Cate Blanchett (12:34):
A cut test is used to determine whether the seeds
are of good quality.
Ted Chapman (12:39):
So, I'm going to give you the tools of the
trade. So, some snips, just watch yourself.
Cate Blanchett (12:43):
Little, they're very sharp scissors.
Ted Chapman (12:45):
And so, the question is, can you grip that seed
in the end of your fingertips? Carefully slice off the top.
Cate Blanchett (12:54):
Am I going into the dark part of the seed?
Ted Chapman (12:56):
In the dark part, yeah, right through the middle. Nice. And then I'll give you that
lens. And then if you hold up joy and then
have a look, see if you can see-
Cate Blanchett (13:05):
Oh gosh.
Ted Chapman (13:05):
... anything white and flowery in there.
Cate Blanchett (13:10):
Well, on the edge of the seed, there's a tiny bit
of... It almost looks like someone's moved to a white pencil
along the edge of it.
Ted Chapman (13:19):
That's probably what it will look like is like...
Cate Blanchett (13:20):
Do you want to check?
Ted Chapman (13:20):
It will look like a little white,
Cate Blanchett (13:24):
Little tiny little dots. You see?
Ted Chapman (13:28):
So, that's the end of sperm of the seed. It's its
food store. So, sometimes we can also see the embryo,
which is the little seedling waiting to come out. And if we
can see those things, it gives a clue that the seed
has got the potential to germinate. We don't know if
it definitely will, but it potentially could. If it's empty
or moldy or there's a grub, then we know it's
not good. So, the cut test is a really important
(13:50):
way we go about in the field just assessing the
likely quality of the seed. Yep. That seed's good. Yep.
So, yellow rattles, it's a very thin seed.
Cate Blanchett (14:01):
Yes. And the bulk of it's dark.
Ted Chapman (14:03):
And the bulk of it's dark. But those white flowery bits tell me that that
seed is good. So, we've cut tested five in total,
four of which were good and one of which was
not good. So, we could say for the purposes of
our collection today, that about 80% of the seed here
is full and good. So, what I would do now
(14:26):
is I'm going to take my 1. 4 million seeds
in this whole population. I'm going to work out 80%
of that. So, you've got 1, 120,000 approximately good seed
in the population. But our absolute maximum that we could
collect here is only 20% of that seed, which is 224,
(14:48):
000 seed. So, there's tons of seed here. We don't
need worry about depleting the natural population.
Cate Blanchett (14:53):
Over one million seeds are available here, an astonishing number.
Ted Chapman (14:58):
To make our conservation collection, we're going to want to
get 25 heads each because there are three of us
collecting today. So, we're pretty much ready to go.
Cate Blanchett (15:06):
We fan out, walking slowly, each of us following our
own line in parallel with one another gathering as we go.
Ted Chapman (15:13):
We're walking towards that orange marker. It's fine if we
wave around a little bit. It doesn't have to be
a dead straight line, but it just means that we'll
cover the whole area between us.
Cate Blanchett (15:26):
This is when seed collecting gets competitive. I'm trying to
get a lot of heads. There we go.
Isabel Negri (15:33):
Don't be tempted to just collect the pretty ones.
Ted Chapman (15:36):
No.
Isabel Negri (15:36):
You want the ugly ones too.
Cate Blanchett (15:39):
No, that's a different one. Yeah, it hasn't got so
many heads on it. These ones are really rattley. I
may have felt slightly competitive, but ultimately, this is a
team sport.
Ted Chapman (15:54):
You've actually done it.
Cate Blanchett (15:55):
Have I?
Ted Chapman (15:55):
How many have you got?
Isabel Negri (15:56):
I think I've got about 25.
Ted Chapman (15:58):
Okay. All right.
Cate Blanchett (16:00):
I think I've got about 13.
Ted Chapman (16:01):
Okay.
Cate Blanchett (16:02):
Do I get the job?
Ted Chapman (16:03):
Yeah.
Cate Blanchett (16:06):
The yellow rattle heads are scooped up into a bag,
carefully labeled and a specimen is pressed. This part of
the process is now complete. So, once we've collected the
seeds, what happens now? Where do we go? Where do
these little seeds travel?
Ted Chapman (16:19):
So, those seeds would be returned as quickly as possible
to the drying room at the Millennium Seed Bank. And
that's where they'll start their drying and can begin their
journey through being cleaned and tested and ultimately banked.
Cate Blanchett (16:34):
Come on little seeds. Later, I'll be going inside the
MSB to see what happens to the seeds when they
arrive at Wakehurst. Collections like this are essential to the
work of the Millennium Seed Bank, but they're carried out
not just on its doorstep, but also in collaboration with
(16:57):
partner organisations all over the world. With a global network
across nearly 100 countries, the MSB works with experts to
help inform projects that will save biodiversity in myriad places.
Nattanit Yiamthaisong (17:11):
I am Nattanit Yiamthaisong. I am a PhD student in Chiang
Mai University. I'm working with FORRU, which is Forest Restoration Research
Unit or in Thai name we call, Nuay Wichai Fuenfu Pa. FORRU and
(17:31):
MSB is like we are the partnership for collaboration around more
than 25 years. FORRU do the research about the restoration
and we collect the seeds for sent to the MSB and I
am the small part in the team for collect the seeds to send
it here.
Cate Blanchett (17:50):
Nattanit is spending three months at the MSB as part
of her PhD studying how varying temperatures influence seed germination.
Nattanit Yiamthaisong (17:59):
We want to know if the climate change or the global warming in the
future, the temperature will increase is maybe effect with the seed
and germination of the seed. We want to know if
the temperature increases effect with the seed or not. For two species from Thailand
in different temperature from five to 45 degrees Celsius.
Cate Blanchett (18:22):
She has come to the Millennium Seed Bank to access
equipment she doesn't have in Thailand.
Nattanit Yiamthaisong (18:27):
I would like to learn about everything here because everything
is new thing for me. In Thailand, we have a
lot of limitation because we don't have enough incubator, we
don't have enough machine to handle with the seed. Then I have
to come here to use the facility, use the machine
here. It's like a x- ray machine, aspirator or the incubator
(18:52):
that I have to germinate the seed. After I finished
the germination here, I have to analyze it in Thailand.
Cate Blanchett (19:01):
Nattanit's research allows us to understand how different seed species
respond to shifting temperatures. Knowledge that could guide us in
choosing the right seeds to use for future restoration. Her
work was made possible by an MSB project called the
Western Global Tree Seed Bank. Nattanit says that their funding
(19:22):
has inspired and opened new doors for her career.
Nattanit Yiamthaisong (19:26):
The scholarship or the fund for the student is so
good for Thai student or every student who do the
research for approve the research and for learn the new things. And
everyone here is so nice. I like everything here. And the
machine is so good, it's so new. I think the
(19:49):
MSB and the Seed Bank is like a treasure in the future for everyone. It's like a
hope for everyone in the future, because we don't know what
happened in the future, right? If we have the result
in my hand, we can do anything in the future.
Cate Blanchett (20:06):
Once collected, the seeds must be carefully processed to ensure
that they survive in the seed bank so that researchers
both here at Wakehurst and around the world can use them
for study or habitat restoration. It's a meticulous and time-
consuming process. So, not many people get to do this.
(20:27):
I've been invited inside the lab in the Millennium Seed
Bank to get a better understanding of how the seeds
are actually banked. And showing me around is seed curator,
Sian McCabe. Hello, Sian.
Sian McCabe (20:40):
Hi, nice to meet you.
Cate Blanchett (20:40):
Hi. Hey, hey. Can you explain what are we going
to do today? Oh, is that to clean my feet?
Sian McCabe (20:48):
Yeah, yeah. Just to make sure you're not bringing any-
Cate Blanchett (20:50):
There we go.
Sian McCabe (20:50):
... outdoor.
Cate Blanchett (20:50):
Everything's nice and squeaky clean. Biosecurity is important at the MSB. So,
I slip on a lab coat. Very official.
Sian McCabe (21:00):
This is where the magic happens. We've stepped into the cleaning
lab, the space where every single seed is carefully freed
from dust and debris and seeds that are empty or
infested are removed. But before they're cleaned, there's a very
important stop they have to make.
Cate Blanchett (21:18):
So, this looks like a freezer, but it's more like
a sauna.
Sian McCabe (21:21):
So, it's 18 degrees Celsius and 15% relative humidity. And
this is really important because with every 1% a seed
is dried, it can double the lifespan of the seed.
Cate Blanchett (21:37):
And then what do you do with say, a recalcitrant
seed? So, the seeds that won't withstand the drying process.
Sian McCabe (21:42):
Yep. So, we have other different humidity rooms. So, this
one is at 70%, so we...
Cate Blanchett (21:49):
Quite a big difference humidity.
Sian McCabe (21:49):
So, yeah.
Cate Blanchett (21:51):
Sian told me that 90% of the seeds collected are
what we call orthodox. And those orthodox seeds can withstand
normal drying and freezing processes. The remaining 10% can't.
Sian McCabe (22:04):
We know not to put them into the dry room
and to treat them regarding...
Cate Blanchett (22:07):
And what's an example of a non- orthodox seed like that?
Sian McCabe (22:11):
They tend to be food, so quite yummy. So, we've
got avocado and I wouldn't recommend eating it, but acorns
are recalcitrant. So, they're just a few examples. So, there's
the door.
Cate Blanchett (22:23):
Okay.
Sian McCabe (22:23):
And this is the airlock area.
Cate Blanchett (22:28):
Ooh. Through double airlock doors, we move into a cool
unassuming room with every corner stacked and packed with crates.
Sian McCabe (22:37):
So, we need to make sure that door's shut, that's it,
before opening this one to protect our seeds.
Cate Blanchett (22:42):
Like Star Wars.
Sian McCabe (22:43):
Yeah, if you just push it.
Cate Blanchett (22:44):
It resembles a supermarket store room. Yet here, I'm surrounded
by seeds from all over the world. There's lots of
plastic storage trays and there's some seeds in envelopes of
South Africa, Sierra Leone, Georgia, Madagascar, they're from all over.
Greece, Ghana, Mozambique. Goodness.
Sian McCabe (23:05):
Yeah, all these crates to the right are ready to
clean and to process.
Cate Blanchett (23:09):
Given that you've got so many seeds, I mean they
all obviously need to drive for different amounts of time.
That's quite a complicated thing to matter.
Sian McCabe (23:17):
Yeah. Yeah, we have species that are super short- lived,
so they're outlined at the beginning. And with some seeds,
like with the orchid seeds, we come in, we have to process within
two weeks to keep the seeds alive and well. But
with most orthodox non- short lived seeds, six months seems
(23:38):
because we have really big seeds that will take longer
to drive. So, the default position of these collections are
in the dry room. And when we get out to
process them and after each process, they'll go back here
to re- dry.
Cate Blanchett (23:52):
Once the seeds are fully dried, the next step is
to clean them. Oh, there's a rack of metal. They
look like film canisters, but they're not.
Sian McCabe (24:04):
Yeah.
Cate Blanchett (24:04):
What goes on here.
Sian McCabe (24:05):
So, these are sieves. So, similar to what you'd have
in your kitchen, but they're all different pore sizes. So,
we go from the small this end. So, you can
see here that it's a very fine mesh.
Cate Blanchett (24:20):
So, that's for something like dust particle seeds like the
orchid I imagine?
Sian McCabe (24:23):
Yeah, exactly.
Cate Blanchett (24:24):
Wow, I can't imagine how... it feels so solid. How
could anything go through there?
Sian McCabe (24:29):
Yeah, it's sometimes to save the seeds above it and
then the dust falls behind. And then we have the larger
ones at this end. This is for the big tree seeds,
and this is what we use to get most of
the bulk from the collection to separate the seeds and the debris.
Cate Blanchett (24:47):
There's a more high- tech solution too. This looks like
something in a fun arcade.
Sian McCabe (24:52):
This machine is called an aspirator, and that uses airflow
to separate the light parts of the collection to the
heavy part.
Cate Blanchett (25:02):
Looks like you put a coin in and it will travel all the
way along. There's a almost like a big slide. There's
an opening in the top, goes into a slot, then
it goes along a strange convoluted journey bit. It's a
bit like a pinball machine. Is that to shake things
off the seed or...
Sian McCabe (25:21):
Yeah. So, here's the chute. So, it's a bit like
a funnel. We'll just turn it down so the seeds
don't escape.
Cate Blanchett (25:29):
So, you're popping the seeds in the top, like peppercorns.
Sian McCabe (25:34):
There we go. So, in theory, the heavy parts are the
good full seeds and the light parts are the debris
and the empty seeds. So, the light empty seeds get
exposed to the airflow and fly over to the right-
hand side.
Cate Blanchett (25:49):
Down the pinball machine sheet.
Sian McCabe (25:50):
Yeah. And then the heavy seeds fall down.
Cate Blanchett (25:53):
And that's done with air.
Sian McCabe (25:54):
So, this button, you turn right to vary the vibrations
of the plate to move the seeds along.
Cate Blanchett (26:02):
So, they're bouncing off the side of that chute and
then bouncing off it, that's shaking.
Sian McCabe (26:07):
You can see some bits of debris flying over onto
the right-hand.
Cate Blanchett (26:11):
I see the air takes the light debris up and down.
Sian McCabe (26:16):
So, we've got manual sieving, and this is a more high-
tech version. And then the very low- tech version is
we have a rubber mat and a rubber glove.
Cate Blanchett (26:26):
Once the seeds have been cleaned, they are x- rayed
to assess their quality. I hadn't really thought before that
a seed could actually be x- rayed.
Sian McCabe (26:36):
After cleaning, it's really good to see inside of the seed
to see whether there's still any empty seeds or invested
seeds. As you can see in this image, we have
a few different seeds. So, here, you can see the
embryo. So, this is the endosperm surrounding the seed. And
this is...
Cate Blanchett (26:55):
Tiny little thing.
Sian McCabe (26:56):
This is what's going to hopefully turn it into a plant.
So, we have some really bright white images of seeds,
which means that it's a solid, lovely, full content. But
here, can you see...
Cate Blanchett (27:10):
It's like a dark shadow in the middle
Sian McCabe (27:12):
It's a maggot.
Cate Blanchett (27:14):
Oh. It's a maggot?
Sian McCabe (27:17):
Yes.
Cate Blanchett (27:18):
You've got three maggots in that batch?
Sian McCabe (27:20):
Yep, but the problem with maggots is when it comes
to cleaning, if you think back to the aspirator that
it's all based on weight difference. So, we can't necessarily
clean out this collection because the weight of a seed with
a maggot in weighs a similar amount to a full
(27:41):
seed. So, we try our best, but the maggots are
usually not with us after six months of drying.
Cate Blanchett (27:50):
After being x- rayed, the seeds are counted and then
taken underground to the vaults, the seed bank itself. Downstairs?
Sian McCabe (27:59):
Yes.
Cate Blanchett (28:00):
Sian leads me there next, descending a steep metal spiral
staircase to arrive at the heart of the building concealed
behind a thick metal door. So, this is the door
of the vault.
Sian McCabe (28:13):
This is the door of...
Cate Blanchett (28:13):
And that is the longest key I've ever seen in my life.
Sian McCabe (28:16):
Say about 10, 15 centimeters long.
Cate Blanchett (28:20):
I would say it is.
Sian McCabe (28:20):
So, we just need to open the very heavy door. Welcome
in. This is actually the most biodiverse place in the world.
Cate Blanchett (28:36):
In this very room?
Sian McCabe (28:37):
Yeah, because we have so many species in.
Cate Blanchett (28:39):
So, are these technically called the vaults?
Sian McCabe (28:42):
Yeah, these are the vaults where their seeds are kept
at minus 20.
Cate Blanchett (28:49):
Oh my goodness. It is absolutely freezing in here. Arctic.
It feels so alien. Almost like an old- fashioned library.
You're expecting library cards to be pulled out from these
metal trays. But along the right- hand side from meters
and meters and meters are a whole lot of preserving
(29:09):
jars, which look like the ones that I've got at
home in my pantry.
Sian McCabe (29:13):
Yeah. So, the pickling jars are actually the best glass
jars that we have.
Cate Blanchett (29:18):
And on the right- hand side, ooh, it's really icy.
On this side here, they almost look like tiny little
medicine or pill bottles.
Sian McCabe (29:27):
Yeah.
Cate Blanchett (29:28):
And so, some seeds are stored in the preserving jars
and some?
Sian McCabe (29:33):
It all depends on the size of the collection. I
can show you some examples in the warmer.
Cate Blanchett (29:38):
So, that's minus 20?
Sian McCabe (29:39):
Yeah, minus 20.
Cate Blanchett (29:40):
I've been cold dipping, but really that is quite cold.
And how many times a day do you go in there?
Sian McCabe (29:45):
Probably once or twice a week, but we had a
fluffy hat with ears on to protect us, two gloves
and a really big coat that makes me look 10
times the size.
Cate Blanchett (29:58):
But not all the seeds remain here locked away indefinitely.
Sian McCabe (30:02):
When our seeds are ready to bank, we separate them
into two parts. So, we have an active part. That's
the parts that gets used for germination testing and for
research and for restoration. And then the other part, which
is the base just gets left there because we're not
(30:23):
sure. And taking seeds in and out of the bank
too often, we don't want to compromise the quality of a
collection. So, these are all glass. So, it's really nice
to see the seeds, but we're moving more onto these
foil bags.
Cate Blanchett (30:41):
Taking up less space.
Sian McCabe (30:42):
And if you drop them accidentally, they don't break.
Cate Blanchett (30:47):
But these new bags that you've got, look a little
bit like my daughter got some astronaut's ice cream.
Sian McCabe (30:53):
Oh, yeah.
Cate Blanchett (30:53):
That was look like it came into one of those pancakes.
Sian McCabe (30:56):
Yeah, this is exactly it. So, it's a thick foil
sachet that we heat seal. So, yeah, exactly what they
have in space.
Cate Blanchett (31:04):
Storing the seeds is one thing, but the team here
must also ensure that they can be brought back to
life revived as fully fledged plants when needed. Just as
we heard in episode one, after the fires in South
Australia, this process begins just a few months after the
seeds are first banked and then is repeated at 5-
or 10- year intervals. It is a meticulous and monumental
(31:29):
task.
Sian McCabe (31:31):
You ready for the heat?
Cate Blanchett (31:34):
Oh, and here we are.
Sian McCabe (31:36):
So, this is our germination lab.
Cate Blanchett (31:44):
Oh, wow. The smell is really, it's very strong, very earthy.
You can tell things are growing in here. You can really smell
the soil. These ones are growing, the clappers. Those ones are massive. They almost look like
cockroaches, and those ones almost look like a moldy chocolate.
(32:04):
They're very strange and the shape of them is really
varied because normally, you think about a seed as looking uniform.
Sian McCabe (32:10):
Yeah, a bit like humans. Even though we are the same
species, we all look a bit different, don't we?
Cate Blanchett (32:15):
Really?
Sian McCabe (32:17):
So, yeah.
Cate Blanchett (32:20):
We're surrounded by Petri dishes filled with germinating seeds. Tiny
emerging plants of every shape and size. Some are gnarled,
like potato roots, others almost otherworldly like something from science
fiction. The lab simulates day and night, 12 hours of
(32:40):
UV light followed by 12 hours of darkness. What's this
one here?
Sian McCabe (32:46):
So, this is a goat willow from Scotland. And as
you can see, it's got really good germination. So, you
can see the part that's coming out from the seed
is what we call a radical. And the cotyledons, which
are the first leads coming out. And this is really
good because Salix, the goat willow, it's supposed to be
(33:09):
super short- lived, but this has been in our bank
since 2019. So, this is five years after checking to
check it's still alive-
Cate Blanchett (33:18):
It's still doing.
Sian McCabe (33:18):
... and it's still alive.
Cate Blanchett (33:20):
And so, now that all of these little goat willows
have germinated, will any of those get planted out?
Sian McCabe (33:26):
Only if they're needed for identification purposes or restoration purposes.
Cate Blanchett (33:31):
Thank you. Thanks so much. I've had the privilege of going inside
the working spaces of the MSB and of witnessing the seed's
journey from collection to germination. But this is not a
world hidden away. Anyone visiting Wakehurst can step into the
(33:52):
atrium here at the Millennium Seed Bank, peer into the
labs, and even look down at the vault door. What
really strikes me is how these tiny, fragile beginnings hold
such extraordinary promise. I mean, each sprouting seed is a
quiet guardian of our future, a small, but vital piece
(34:13):
of the puzzle protecting our planet. Join me next time
as we look forward to the future these seeds may
protect to the vision driving the final chapter of our
story and the innovative science behind it. This is Unearthed:
The need for seeds. Please follow us wherever you find
(34:36):
your podcasts. And hey, leave us a review so others
can find us too. And I invite you to join
me in supporting the vital work of the Millennium Seed
Bank by making a donation today. You can just click
the link in the episode description to learn more. Until
next time, thanks for listening.
You really are on the edge of South Downs. Could
(00:04):
you describe it as a natural landscape or...
Ted Chapman (00:06):
So, the landscape we're driving through now is not really
natural. No. So, these fields are arable fields, so they
would normally be gray cereals, but for this year, at
least they've been sown with it looks like some kind
of wild seed mix.
Cate Blanchett (00:20):
I'm in a Jeep lurching over a dusty single track
road where deep in the South Downs National Park, which
is just beyond Brighton on England's southern coast.
Ted Chapman (00:31):
Skylarks are taking advantage of that because they nest in
the ground. So, they're probably nesting.
Cate Blanchett (00:34):
You can hear them outside. That's Ted Chapman behind the
Wheel UK Conservation Partnerships Coordinator at Kew's Millennium Seed Bank
at Wakehurst. He's also my guide for today.
Ted Chapman (00:46):
So, these hills that we're driving over now are all
chalk, and the chalk is really close to the surface.
So, the soil here is only 10 or 20 centimeters deep and
that very chalky soil, very low fertility, very sharply drained,
it drains really quickly. That's really what informs the type
of vegetation that we have, and that's what makes this
(01:10):
habitat special because these types of soil conditions and rock
conditions are not found very commonly.
Cate Blanchett (01:18):
We're heading to Castle Hill National Nature Reserve, which is
looked after by Natural England, and I'm joining Ted and
his team to collect wild seeds. Is this somewhere where
you'd come see collecting a lot? Is this an annual pilgrimage?
Ted Chapman (01:33):
So, we've collected a lot of seed in Castle Hill
in sites like this, because the chalk grassland supports an
exceptionally diverse flora, and many of those species are highly
specialized and quite rare. So, because we're often targeting threatened
species, we're often found in places like this.
Cate Blanchett (01:59):
The MSB's central mission is to gather wild seeds from
across the globe, preserving them to safeguard the future of
our planet. This work focuses on species under threat around
the world, often found in far- flung countries. However, you
might be surprised to know that some of the species
most in need of protection are much closer to home.
(02:21):
It's just magnificent. It's so wide and open and there's a big smudge
of red down there though poppies.
Ted Chapman (02:28):
Yeah, we're going to get a close- up view of
these beautiful poppies.
Cate Blanchett (02:31):
But just as important as place is time. In seed
collecting, timing is everything. What we're hoping for today is that
our visit coincides with the precise moment the seeds are
ready to be gathered, so that we can follow their
journey as they're carefully processed and then stored for safekeeping
(02:54):
in the vaults of the Millennium Seed Bank at Wakehurst.
I am Cate Blanchett, Kew's ambassador for Wakehurst, and this
is Unearthed
Ted Chapman (03:12):
So, we need to get through this gate.
Cate Blanchett (03:14):
Yeah, I can do it. It's the gate etiquette. You
learn that in Australia very quickly. Oh, I see those
two bars there.
Ted Chapman (03:24):
So, the last thing we want is off- road bikes, off-
road vehicles coming into the reserve and destroying the habitat,
which would just happen so easily. You can imagine these
habitats takes centuries or millennia to evolve, but only seconds
to destroy.
Cate Blanchett (03:38):
Yes, yeah. Gosh, there's this team flowers, isn't it?
Ted Chapman (03:41):
Yeah.
Cate Blanchett (03:44):
They're heavy.
Ted Chapman (03:44):
They are heavier. Are you okay with that? And then you twist it at the top. That's
it. Oh, great. Okay.
Cate Blanchett (03:55):
Here we go.
Ted Chapman (03:55):
Okay. In we go.
Cate Blanchett (04:03):
We pass through multiple gates and descend into a valley.
It's wildly overgrown with shrubs and vegetation encroaching on the
track. And then as we lurch around a corner, the
tree's clear and I'm greeted with the most beautiful vista.
Oh my goodness, this is magnificent. It looks so ancient
(04:24):
because the hills are just given away to a flat
plane. It's got a smattering of poppies. And what's the
yellow? Is that this grass... Man, it's so beautiful. It's
almost like someone's taken a brush with a thousand colours.
Ted Chapman (04:39):
Yes, yeah. So, the reserve is on these steep hillsides
and then at the bottom of the valley, we've got
this flatter area with deeper soils. And then we've got
this wash of poppies. So, beautiful.
Cate Blanchett (04:50):
Something out of The Wizard of Oz. So, if you find
me asleep in there, rescue me.
Ted Chapman (04:57):
So, the slope ahead of us is where we're going
to be doing our harvesting today. And this is Castle
Hill itself.
Cate Blanchett (05:02):
You mean the green quite vertiginous- looking slope ahead of
us that's got the...
Ted Chapman (05:07):
Exactly. So, we can see-
Cate Blanchett (05:08):
The strawberry on the top.
Ted Chapman (05:08):
... we've got the scrub at the top. We've got
this arable field at the bottom. We've got this slightly
flatter, rough bit in between. And that area was ploughed
in the second world war. And that's why even now,
it's still very different to the ancient short grassland, which
is on the steep slope.
Cate Blanchett (05:29):
And what was attempted to be grown there?
Ted Chapman (05:32):
That would've been crops for eating in that dig for
victory effort. So, these soils are with chemical fertilizers, they're
quite amenable to growing things like cereals, wheat, barley, flax.
Now that farming ceased some decades ago, but even with
decades of very careful management, you can see the grassland
at the bottom of the slope is very different to
the grasslands on the sides.
Cate Blanchett (05:53):
It's really green and tufty.
Ted Chapman (05:55):
Yeah. So, that is good, but we don't want too
much of that. We need a good balance.
Cate Blanchett (06:01):
So, what makes this spot so special apart from its
incredible beauty?
Ted Chapman (06:06):
It's really the quality of the chalk grassland. So, we're
going to be in one of the nicest patches in
just a second. You'll see the diversity of species and they're
all tiny weeny because it's so infertile, but there are
many, many species packed in. So, we can record 40
or more species in a square metre here. So, this
is one of the most plant- diverse habitats in Western
(06:27):
Europe on this small scale. So, it's really special floristically
and it's of course the vegetation then supports the butterflies,
the other invertebrates, the birds that are associated with the
invertebrates and so forth. So, that's really why this is
such a special place.
Cate Blanchett (06:44):
After a quick safety briefing from Ted and his colleague,
Isabel Negri, UK Conservation projects officer at the MSB, we start
to clamber up the hill. We wade through some tall
grasses at the bottom, but they soon thin out. There's
so many varieties of plants and I'm sure a myriad
of insects all thriving underneath my feet.
Ted Chapman (07:07):
We try to tread lightly in habitats like this where
we can. So, we've got into the chalk grassland. It's
very low.
Cate Blanchett (07:17):
And not as dense.
Ted Chapman (07:18):
Much, much less dense. And if you start looking into
the sword, you can see there are lots of different species, different
grasses, different species, and they're all little thistle there, a little bedstraw
there, all growing intermeshed, one with another. And underneath, you can
see it now looking very dry and droughty this grey soil.
(07:40):
That's the very chalky alkaline soil. So, this site is
grazed by cattle. Grazing is essential because without the grazing
this would revert through scrub to woodland and the grassland
would be lost. So, that sustained grazing at the right
level over centuries and centuries is what has created and
maintained this landscape.
Cate Blanchett (07:59):
As Ted started pointing out different plants, I began to
think I was getting rather good at spotting unusual species.
I should work at the MSB.
Ted Chapman (08:07):
Let's head up. We'll find... There's always so much to see.
Cate Blanchett (08:12):
Yes. It's hard not to get waylaid.
Ted Chapman (08:14):
Yeah.
Cate Blanchett (08:14):
What's that little?
Ted Chapman (08:17):
That is rabbit poo.
Cate Blanchett (08:19):
Oh, great. I might put that in my pocket
Ted Chapman (08:21):
So, we don't aim to collect that.
Cate Blanchett (08:23):
We can use it later. Chocolate covered rabbit poo. Here I
was, thinking I'd found a rare seed rabbit poo. Clearly,
I'm not going to get a job at Wakehurst. After
my identification of the rabbit poo, we continued up the
hill making our way towards some orange markers.
Ted Chapman (08:45):
So, these markers mark out where we've got a really lovely
population of yellow rattle. So, yellow rattle is what we've
come here to collect today.
Cate Blanchett (08:55):
And what's so important about the yellow rattle?
Ted Chapman (08:58):
So, yellow rattle is a semi- parasitic species. So, that
means it produces its own food, but it also parasitizes
other species growing with it. And that means it reduces
their vigor. And that makes it quite important in this
habitat, because it helps balance the really vigorous species against
the more delicate species and allows those more delicate species
(09:19):
to thrive. So, it's really very important for the kind
of function of the plants growing here.
Cate Blanchett (09:24):
It's a regulator.
Ted Chapman (09:25):
It's a regulator, like a community engineer almost. It's found
in a lot of grassland sites. We specifically need to
collect it now because we've used quite a lot of
the collection that we have for research work that we've
done looking at the germination needs of this species. So,
yellow rattle is actually a species which has a very
(09:46):
narrow temperature window in which it can germinate. And so,
we've done some work and Isabel has been involved in
this to work out exactly what the minimum and maximum
temperature range that yellow rattle needs. And then we model
that against climate change. So, we think in 50 years'
time, will the climate still provide the conditions that yellow
rattle and other species need to germinate? So, many species
(10:09):
are resilient and they will be able to regenerate successfully
in a warm climate. But yellow rattle is an example
of a species which is quite vulnerable, because it needs
cold winter conditions to break dormancy and germinate. So, it's
important to understand that and start thinking about how we
can manage grasslands and restoration projects to counter that and
(10:31):
build adaptation and make sure this particularly important species survives.
So, we've used seed to support that research, so we
need to replenish that seed in the seed bank. So, we've got it
for next time. So, the first thing we're going to
do is find similar rattle and take a look at
it. Some specimens here.
Cate Blanchett (10:50):
It's got a sort of a reddish brown stem with almost like
two little pods, green pods.
Ted Chapman (10:57):
That's right. Yeah. Will it rattle? That's the seed rattling
around and that's how it gets its name.
Cate Blanchett (11:06):
So, you want to collect them when they're dried?
Ted Chapman (11:08):
Exactly right. So, we want to collect seed at the
point of natural dispersal. So, that's when it's being dispersed
into the environment. That's when it's mature, it's when its
longevity. So, the amount of time it will be able to
survive in the seed bank is at its greatest.
Cate Blanchett (11:22):
It struck me as almost paradoxical that we were gathering
seeds from the very habitat where I just learned how
vital they are as nature's own community engineers. But Ted
and his team work by a clear principle. You never
take more than 20% of the seeds in the field.
Each of the pods are filled with tiny seeds. And
(11:43):
so, our collection begins with some counting.
Ted Chapman (11:50):
Okay, I make that 25 in my patch.
Cate Blanchett (11:55):
There's quite a lot here actually.
Isabel Negri (11:57):
How many did you find?
Cate Blanchett (11:58):
I think about between 35 and 40 in a square meter.
Isabel Negri (12:02):
Oh.
Ted Chapman (12:02):
Okay. Yeah, we average at about 20 plants per square meter.
Cate Blanchett (12:09):
And a little bit of maths.
Ted Chapman (12:11):
I've crunched the numbers and I can tell you that
we have approximately 1. 4 million seeds in our sampling
area here of yellow rattle.
Cate Blanchett (12:19):
Yeah, down.
Ted Chapman (12:20):
There's always tonnes more seed than you think there is.
Cate Blanchett (12:22):
And just before we start collecting, there's one more important step.
Ted Chapman (12:26):
If you've got some seed in your hand, Isabel-
Isabel Negri (12:28):
Yes.
Ted Chapman (12:28):
... shall we see if we can do a cut test?
Isabel Negri (12:33):
Yeah. I'll pass it to Kate. There you go.
Cate Blanchett (12:34):
A cut test is used to determine whether the seeds
are of good quality.
Ted Chapman (12:39):
So, I'm going to give you the tools of the
trade. So, some snips, just watch yourself.
Cate Blanchett (12:43):
Little, they're very sharp scissors.
Ted Chapman (12:45):
And so, the question is, can you grip that seed
in the end of your fingertips? Carefully slice off the top.
Cate Blanchett (12:54):
Am I going into the dark part of the seed?
Ted Chapman (12:56):
In the dark part, yeah, right through the middle. Nice. And then I'll give you that
lens. And then if you hold up joy and then
have a look, see if you can see-
Cate Blanchett (13:05):
Oh gosh.
Ted Chapman (13:05):
... anything white and flowery in there.
Cate Blanchett (13:10):
Well, on the edge of the seed, there's a tiny bit
of... It almost looks like someone's moved to a white pencil
along the edge of it.
Ted Chapman (13:19):
That's probably what it will look like is like...
Cate Blanchett (13:20):
Do you want to check?
Ted Chapman (13:20):
It will look like a little white,
Cate Blanchett (13:24):
Little tiny little dots. You see?
Ted Chapman (13:28):
So, that's the end of sperm of the seed. It's its
food store. So, sometimes we can also see the embryo,
which is the little seedling waiting to come out. And if we
can see those things, it gives a clue that the seed
has got the potential to germinate. We don't know if
it definitely will, but it potentially could. If it's empty
or moldy or there's a grub, then we know it's
not good. So, the cut test is a really important
(13:50):
way we go about in the field just assessing the
likely quality of the seed. Yep. That seed's good. Yep.
So, yellow rattles, it's a very thin seed.
Cate Blanchett (14:01):
Yes. And the bulk of it's dark.
Ted Chapman (14:03):
And the bulk of it's dark. But those white flowery bits tell me that that
seed is good. So, we've cut tested five in total,
four of which were good and one of which was
not good. So, we could say for the purposes of
our collection today, that about 80% of the seed here
is full and good. So, what I would do now
(14:26):
is I'm going to take my 1. 4 million seeds
in this whole population. I'm going to work out 80%
of that. So, you've got 1, 120,000 approximately good seed
in the population. But our absolute maximum that we could
collect here is only 20% of that seed, which is 224,
(14:48):
000 seed. So, there's tons of seed here. We don't
need worry about depleting the natural population.
Cate Blanchett (14:53):
Over one million seeds are available here, an astonishing number.
Ted Chapman (14:58):
To make our conservation collection, we're going to want to
get 25 heads each because there are three of us
collecting today. So, we're pretty much ready to go.
Cate Blanchett (15:06):
We fan out, walking slowly, each of us following our
own line in parallel with one another gathering as we go.
Ted Chapman (15:13):
We're walking towards that orange marker. It's fine if we
wave around a little bit. It doesn't have to be
a dead straight line, but it just means that we'll
cover the whole area between us.
Cate Blanchett (15:26):
This is when seed collecting gets competitive. I'm trying to
get a lot of heads. There we go.
Isabel Negri (15:33):
Don't be tempted to just collect the pretty ones.
Ted Chapman (15:36):
No.
Isabel Negri (15:36):
You want the ugly ones too.
Cate Blanchett (15:39):
No, that's a different one. Yeah, it hasn't got so
many heads on it. These ones are really rattley. I
may have felt slightly competitive, but ultimately, this is a
team sport.
Ted Chapman (15:54):
You've actually done it.
Cate Blanchett (15:55):
Have I?
Ted Chapman (15:55):
How many have you got?
Isabel Negri (15:56):
I think I've got about 25.
Ted Chapman (15:58):
Okay. All right.
Cate Blanchett (16:00):
I think I've got about 13.
Ted Chapman (16:01):
Okay.
Cate Blanchett (16:02):
Do I get the job?
Ted Chapman (16:03):
Yeah.
Cate Blanchett (16:06):
The yellow rattle heads are scooped up into a bag,
carefully labeled and a specimen is pressed. This part of
the process is now complete. So, once we've collected the
seeds, what happens now? Where do we go? Where do
these little seeds travel?
Ted Chapman (16:19):
So, those seeds would be returned as quickly as possible
to the drying room at the Millennium Seed Bank. And
that's where they'll start their drying and can begin their
journey through being cleaned and tested and ultimately banked.
Cate Blanchett (16:34):
Come on little seeds. Later, I'll be going inside the
MSB to see what happens to the seeds when they
arrive at Wakehurst. Collections like this are essential to the
work of the Millennium Seed Bank, but they're carried out
not just on its doorstep, but also in collaboration with
(16:57):
partner organisations all over the world. With a global network
across nearly 100 countries, the MSB works with experts to
help inform projects that will save biodiversity in myriad places.
Nattanit Yiamthaisong (17:11):
I am Nattanit Yiamthaisong. I am a PhD student in Chiang
Mai University. I'm working with FORRU, which is Forest Restoration Research
Unit or in Thai name we call, Nuay Wichai Fuenfu Pa. FORRU and
(17:31):
MSB is like we are the partnership for collaboration around more
than 25 years. FORRU do the research about the restoration
and we collect the seeds for sent to the MSB and I
am the small part in the team for collect the seeds to send
it here.
Cate Blanchett (17:50):
Nattanit is spending three months at the MSB as part
of her PhD studying how varying temperatures influence seed germination.
Nattanit Yiamthaisong (17:59):
We want to know if the climate change or the global warming in the
future, the temperature will increase is maybe effect with the seed
and germination of the seed. We want to know if
the temperature increases effect with the seed or not. For two species from Thailand
in different temperature from five to 45 degrees Celsius.
Cate Blanchett (18:22):
She has come to the Millennium Seed Bank to access
equipment she doesn't have in Thailand.
Nattanit Yiamthaisong (18:27):
I would like to learn about everything here because everything
is new thing for me. In Thailand, we have a
lot of limitation because we don't have enough incubator, we
don't have enough machine to handle with the seed. Then I have
to come here to use the facility, use the machine
here. It's like a x- ray machine, aspirator or the incubator
(18:52):
that I have to germinate the seed. After I finished
the germination here, I have to analyze it in Thailand.
Cate Blanchett (19:01):
Nattanit's research allows us to understand how different seed species
respond to shifting temperatures. Knowledge that could guide us in
choosing the right seeds to use for future restoration. Her
work was made possible by an MSB project called the
Western Global Tree Seed Bank. Nattanit says that their funding
(19:22):
has inspired and opened new doors for her career.
Nattanit Yiamthaisong (19:26):
The scholarship or the fund for the student is so
good for Thai student or every student who do the
research for approve the research and for learn the new things. And
everyone here is so nice. I like everything here. And the
machine is so good, it's so new. I think the
(19:49):
MSB and the Seed Bank is like a treasure in the future for everyone. It's like a
hope for everyone in the future, because we don't know what
happened in the future, right? If we have the result
in my hand, we can do anything in the future.
Cate Blanchett (20:06):
Once collected, the seeds must be carefully processed to ensure
that they survive in the seed bank so that researchers
both here at Wakehurst and around the world can use them
for study or habitat restoration. It's a meticulous and time-
consuming process. So, not many people get to do this.
(20:27):
I've been invited inside the lab in the Millennium Seed
Bank to get a better understanding of how the seeds
are actually banked. And showing me around is seed curator,
Sian McCabe. Hello, Sian.
Sian McCabe (20:40):
Hi, nice to meet you.
Cate Blanchett (20:40):
Hi. Hey, hey. Can you explain what are we going
to do today? Oh, is that to clean my feet?
Sian McCabe (20:48):
Yeah, yeah. Just to make sure you're not bringing any-
Cate Blanchett (20:50):
There we go.
Sian McCabe (20:50):
... outdoor.
Cate Blanchett (20:50):
Everything's nice and squeaky clean. Biosecurity is important at the MSB. So,
I slip on a lab coat. Very official.
Sian McCabe (21:00):
This is where the magic happens. We've stepped into the cleaning
lab, the space where every single seed is carefully freed
from dust and debris and seeds that are empty or
infested are removed. But before they're cleaned, there's a very
important stop they have to make.
Cate Blanchett (21:18):
So, this looks like a freezer, but it's more like
a sauna.
Sian McCabe (21:21):
So, it's 18 degrees Celsius and 15% relative humidity. And
this is really important because with every 1% a seed
is dried, it can double the lifespan of the seed.
Cate Blanchett (21:37):
And then what do you do with say, a recalcitrant
seed? So, the seeds that won't withstand the drying process.
Sian McCabe (21:42):
Yep. So, we have other different humidity rooms. So, this
one is at 70%, so we...
Cate Blanchett (21:49):
Quite a big difference humidity.
Sian McCabe (21:49):
So, yeah.
Cate Blanchett (21:51):
Sian told me that 90% of the seeds collected are
what we call orthodox. And those orthodox seeds can withstand
normal drying and freezing processes. The remaining 10% can't.
Sian McCabe (22:04):
We know not to put them into the dry room
and to treat them regarding...
Cate Blanchett (22:07):
And what's an example of a non- orthodox seed like that?
Sian McCabe (22:11):
They tend to be food, so quite yummy. So, we've
got avocado and I wouldn't recommend eating it, but acorns
are recalcitrant. So, they're just a few examples. So, there's
the door.
Cate Blanchett (22:23):
Okay.
Sian McCabe (22:23):
And this is the airlock area.
Cate Blanchett (22:28):
Ooh. Through double airlock doors, we move into a cool
unassuming room with every corner stacked and packed with crates.
Sian McCabe (22:37):
So, we need to make sure that door's shut, that's it,
before opening this one to protect our seeds.
Cate Blanchett (22:42):
Like Star Wars.
Sian McCabe (22:43):
Yeah, if you just push it.
Cate Blanchett (22:44):
It resembles a supermarket store room. Yet here, I'm surrounded
by seeds from all over the world. There's lots of
plastic storage trays and there's some seeds in envelopes of
South Africa, Sierra Leone, Georgia, Madagascar, they're from all over.
Greece, Ghana, Mozambique. Goodness.
Sian McCabe (23:05):
Yeah, all these crates to the right are ready to
clean and to process.
Cate Blanchett (23:09):
Given that you've got so many seeds, I mean they
all obviously need to drive for different amounts of time.
That's quite a complicated thing to matter.
Sian McCabe (23:17):
Yeah. Yeah, we have species that are super short- lived,
so they're outlined at the beginning. And with some seeds,
like with the orchid seeds, we come in, we have to process within
two weeks to keep the seeds alive and well. But
with most orthodox non- short lived seeds, six months seems
(23:38):
because we have really big seeds that will take longer
to drive. So, the default position of these collections are
in the dry room. And when we get out to
process them and after each process, they'll go back here
to re- dry.
Cate Blanchett (23:52):
Once the seeds are fully dried, the next step is
to clean them. Oh, there's a rack of metal. They
look like film canisters, but they're not.
Sian McCabe (24:04):
Yeah.
Cate Blanchett (24:04):
What goes on here.
Sian McCabe (24:05):
So, these are sieves. So, similar to what you'd have
in your kitchen, but they're all different pore sizes. So,
we go from the small this end. So, you can
see here that it's a very fine mesh.
Cate Blanchett (24:20):
So, that's for something like dust particle seeds like the
orchid I imagine?
Sian McCabe (24:23):
Yeah, exactly.
Cate Blanchett (24:24):
Wow, I can't imagine how... it feels so solid. How
could anything go through there?
Sian McCabe (24:29):
Yeah, it's sometimes to save the seeds above it and
then the dust falls behind. And then we have the larger
ones at this end. This is for the big tree seeds,
and this is what we use to get most of
the bulk from the collection to separate the seeds and the debris.
Cate Blanchett (24:47):
There's a more high- tech solution too. This looks like
something in a fun arcade.
Sian McCabe (24:52):
This machine is called an aspirator, and that uses airflow
to separate the light parts of the collection to the
heavy part.
Cate Blanchett (25:02):
Looks like you put a coin in and it will travel all the
way along. There's a almost like a big slide. There's
an opening in the top, goes into a slot, then
it goes along a strange convoluted journey bit. It's a
bit like a pinball machine. Is that to shake things
off the seed or...
Sian McCabe (25:21):
Yeah. So, here's the chute. So, it's a bit like
a funnel. We'll just turn it down so the seeds
don't escape.
Cate Blanchett (25:29):
So, you're popping the seeds in the top, like peppercorns.
Sian McCabe (25:34):
There we go. So, in theory, the heavy parts are the
good full seeds and the light parts are the debris
and the empty seeds. So, the light empty seeds get
exposed to the airflow and fly over to the right-
hand side.
Cate Blanchett (25:49):
Down the pinball machine sheet.
Sian McCabe (25:50):
Yeah. And then the heavy seeds fall down.
Cate Blanchett (25:53):
And that's done with air.
Sian McCabe (25:54):
So, this button, you turn right to vary the vibrations
of the plate to move the seeds along.
Cate Blanchett (26:02):
So, they're bouncing off the side of that chute and
then bouncing off it, that's shaking.
Sian McCabe (26:07):
You can see some bits of debris flying over onto
the right-hand.
Cate Blanchett (26:11):
I see the air takes the light debris up and down.
Sian McCabe (26:16):
So, we've got manual sieving, and this is a more high-
tech version. And then the very low- tech version is
we have a rubber mat and a rubber glove.
Cate Blanchett (26:26):
Once the seeds have been cleaned, they are x- rayed
to assess their quality. I hadn't really thought before that
a seed could actually be x- rayed.
Sian McCabe (26:36):
After cleaning, it's really good to see inside of the seed
to see whether there's still any empty seeds or invested
seeds. As you can see in this image, we have
a few different seeds. So, here, you can see the
embryo. So, this is the endosperm surrounding the seed. And
this is...
Cate Blanchett (26:55):
Tiny little thing.
Sian McCabe (26:56):
This is what's going to hopefully turn it into a plant.
So, we have some really bright white images of seeds,
which means that it's a solid, lovely, full content. But
here, can you see...
Cate Blanchett (27:10):
It's like a dark shadow in the middle
Sian McCabe (27:12):
It's a maggot.
Cate Blanchett (27:14):
Oh. It's a maggot?
Sian McCabe (27:17):
Yes.
Cate Blanchett (27:18):
You've got three maggots in that batch?
Sian McCabe (27:20):
Yep, but the problem with maggots is when it comes
to cleaning, if you think back to the aspirator that
it's all based on weight difference. So, we can't necessarily
clean out this collection because the weight of a seed with
a maggot in weighs a similar amount to a full
(27:41):
seed. So, we try our best, but the maggots are
usually not with us after six months of drying.
Cate Blanchett (27:50):
After being x- rayed, the seeds are counted and then
taken underground to the vaults, the seed bank itself. Downstairs?
Sian McCabe (27:59):
Yes.
Cate Blanchett (28:00):
Sian leads me there next, descending a steep metal spiral
staircase to arrive at the heart of the building concealed
behind a thick metal door. So, this is the door
of the vault.
Sian McCabe (28:13):
This is the door of...
Cate Blanchett (28:13):
And that is the longest key I've ever seen in my life.
Sian McCabe (28:16):
Say about 10, 15 centimeters long.
Cate Blanchett (28:20):
I would say it is.
Sian McCabe (28:20):
So, we just need to open the very heavy door. Welcome
in. This is actually the most biodiverse place in the world.
Cate Blanchett (28:36):
In this very room?
Sian McCabe (28:37):
Yeah, because we have so many species in.
Cate Blanchett (28:39):
So, are these technically called the vaults?
Sian McCabe (28:42):
Yeah, these are the vaults where their seeds are kept
at minus 20.
Cate Blanchett (28:49):
Oh my goodness. It is absolutely freezing in here. Arctic.
It feels so alien. Almost like an old- fashioned library.
You're expecting library cards to be pulled out from these
metal trays. But along the right- hand side from meters
and meters and meters are a whole lot of preserving
(29:09):
jars, which look like the ones that I've got at
home in my pantry.
Sian McCabe (29:13):
Yeah. So, the pickling jars are actually the best glass
jars that we have.
Cate Blanchett (29:18):
And on the right- hand side, ooh, it's really icy.
On this side here, they almost look like tiny little
medicine or pill bottles.
Sian McCabe (29:27):
Yeah.
Cate Blanchett (29:28):
And so, some seeds are stored in the preserving jars
and some?
Sian McCabe (29:33):
It all depends on the size of the collection. I
can show you some examples in the warmer.
Cate Blanchett (29:38):
So, that's minus 20?
Sian McCabe (29:39):
Yeah, minus 20.
Cate Blanchett (29:40):
I've been cold dipping, but really that is quite cold.
And how many times a day do you go in there?
Sian McCabe (29:45):
Probably once or twice a week, but we had a
fluffy hat with ears on to protect us, two gloves
and a really big coat that makes me look 10
times the size.
Cate Blanchett (29:58):
But not all the seeds remain here locked away indefinitely.
Sian McCabe (30:02):
When our seeds are ready to bank, we separate them
into two parts. So, we have an active part. That's
the parts that gets used for germination testing and for
research and for restoration. And then the other part, which
is the base just gets left there because we're not
(30:23):
sure. And taking seeds in and out of the bank
too often, we don't want to compromise the quality of a
collection. So, these are all glass. So, it's really nice
to see the seeds, but we're moving more onto these
foil bags.
Cate Blanchett (30:41):
Taking up less space.
Sian McCabe (30:42):
And if you drop them accidentally, they don't break.
Cate Blanchett (30:47):
But these new bags that you've got, look a little
bit like my daughter got some astronaut's ice cream.
Sian McCabe (30:53):
Oh, yeah.
Cate Blanchett (30:53):
That was look like it came into one of those pancakes.
Sian McCabe (30:56):
Yeah, this is exactly it. So, it's a thick foil
sachet that we heat seal. So, yeah, exactly what they
have in space.
Cate Blanchett (31:04):
Storing the seeds is one thing, but the team here
must also ensure that they can be brought back to
life revived as fully fledged plants when needed. Just as
we heard in episode one, after the fires in South
Australia, this process begins just a few months after the
seeds are first banked and then is repeated at 5-
or 10- year intervals. It is a meticulous and monumental
(31:29):
task.
Sian McCabe (31:31):
You ready for the heat?
Cate Blanchett (31:34):
Oh, and here we are.
Sian McCabe (31:36):
So, this is our germination lab.
Cate Blanchett (31:44):
Oh, wow. The smell is really, it's very strong, very earthy.
You can tell things are growing in here. You can really smell
the soil. These ones are growing, the clappers. Those ones are massive. They almost look like
cockroaches, and those ones almost look like a moldy chocolate.
(32:04):
They're very strange and the shape of them is really
varied because normally, you think about a seed as looking uniform.
Sian McCabe (32:10):
Yeah, a bit like humans. Even though we are the same
species, we all look a bit different, don't we?
Cate Blanchett (32:15):
Really?
Sian McCabe (32:17):
So, yeah.
Cate Blanchett (32:20):
We're surrounded by Petri dishes filled with germinating seeds. Tiny
emerging plants of every shape and size. Some are gnarled,
like potato roots, others almost otherworldly like something from science
fiction. The lab simulates day and night, 12 hours of
(32:40):
UV light followed by 12 hours of darkness. What's this
one here?
Sian McCabe (32:46):
So, this is a goat willow from Scotland. And as
you can see, it's got really good germination. So, you
can see the part that's coming out from the seed
is what we call a radical. And the cotyledons, which
are the first leads coming out. And this is really
good because Salix, the goat willow, it's supposed to be
(33:09):
super short- lived, but this has been in our bank
since 2019. So, this is five years after checking to
check it's still alive-
Cate Blanchett (33:18):
It's still doing.
Sian McCabe (33:18):
... and it's still alive.
Cate Blanchett (33:20):
And so, now that all of these little goat willows
have germinated, will any of those get planted out?
Sian McCabe (33:26):
Only if they're needed for identification purposes or restoration purposes.
Cate Blanchett (33:31):
Thank you. Thanks so much. I've had the privilege of going inside
the working spaces of the MSB and of witnessing the seed's
journey from collection to germination. But this is not a
world hidden away. Anyone visiting Wakehurst can step into the
(33:52):
atrium here at the Millennium Seed Bank, peer into the
labs, and even look down at the vault door. What
really strikes me is how these tiny, fragile beginnings hold
such extraordinary promise. I mean, each sprouting seed is a
quiet guardian of our future, a small, but vital piece
(34:13):
of the puzzle protecting our planet. Join me next time
as we look forward to the future these seeds may
protect to the vision driving the final chapter of our
story and the innovative science behind it. This is Unearthed:
The need for seeds. Please follow us wherever you find
(34:36):
your podcasts. And hey, leave us a review so others
can find us too. And I invite you to join
me in supporting the vital work of the Millennium Seed
Bank by making a donation today. You can just click
the link in the episode description to learn more. Until
next time, thanks for listening.
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