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Hi there!
You’re just in time.
Everyone at The Fort has been learning about redwood trees,
the tallest trees in the world.
My friend Sam the Bat has been learning about them, too,
and I was just about to check in with him.
Let’s see what he’s up to today!
Hi, Jessi!
Hi, Sam!
How is your redwood research going?
Uh, it’s going okay.
I was just reading about the habitat that redwoods live in,
but I’m a little confused by something.
Redwood trees tend to grow on the west coast of North America, mostly in California.
But that area of California has a dry season.
Every year, around the same time, it doesn’t rain much,
and the ground gets really dry.
But redwood trees are plants, and I know that plants need water to survive.
I also know that most plants use their underground roots to get water.
So, I was wondering how such big trees can survive the dry season
if there isn’t as much water in the ground.
My guess is that they don’t really need their roots to drink water.
They’re just using something else.
But I was talking to Squeaks about it,
and his guess is that the redwood trees are getting secret water from somewhere.
So, who’s right?
Wow, you two have some great ideas about how redwoods survive the dry season.
And you’re both a bit right!
What?
How?
Well, Squeaks is right that redwood trees have
a special source of water during the dry season.
And you’re right that the redwoods use a different part of the plant
to reach this water, instead of using their roots.
Redwood trees can use their needles to soak up water.
Now, even in the dry season, plants soak up water through their roots.
And they use it to help them grow and survive.
But their needles also come in handy.
They might not look like it, but needles are a type of leaf.
And like all leaves, they’re covered in teeny-tiny holes called stomata.
You wouldn’t really be able to see them without a microscope.
But they’re there, lots of them!
And these hole-like structures have an important job:
They let things in and out of the plant.
Like, when it’s hot outside, stomata let water vapor out of the plant,
and that helps them cool down.
It’s like how when you get too hot, some of the water leaves your body as sweat.
And that helps you cool down!
Water vapor is a little different than the drops of sweat on your body, though.
Water vapor is the same thing as water.
It’s made of all the same stuff, but it looks a lot different
because it’s what’s called a gas.
What does a gas look like?
Great question!
Breathe into your wing, or breathe into your hand.
What do you see?
Nothing?
Exactly!
Gases are invisible.
And believe it or not, you just breathed out a couple of gases,
including some water vapor of your own!
So, when plant leaves or needles let out a bunch of water vapor,
you can’t normally see it.
When water vapor leaves a plant through the leaves like this,
it’s called transpiration.
But transpiration gets rid of water.
How can it help redwood trees get more water?
Well, most of the time, plants use their leaves to let water vapor out.
But when there isn’t enough water being soaked up by the roots,
a plant can use its leaves to let water vapor in from the air around them.
This is called reverse transpiration,
because it’s like regular transpiration…just backward!
And it’s really great for plants that live in habitats like redwood forests.
Can you guess why?
Here’s a hint: What do you notice about this picture of a redwood forest?
Well, it looks really foggy there… wait, fog looks a lot like clouds.
And clouds are made of water!
If all of that fog is water, the redwood trees should be able to suck it up
with their needles using reverse transpiration!
You got it!
Nice work!
Redwood trees usually live in places that are really foggy.
So even when the ground is dry, there can be enough extra water vapor in the air
for plants to use reverse transpiration.
They'll open up the stomata on their needles and drink in the fog.
The redwoods are still using their roots during the dry season,
but since there isn’t a lot of water in the ground,
using their needles helps them get all the water they need.
Thanks for the help, Jessi.
It’s really cool that redwood trees can drink water from the air,
and not just the ground.
And it’s amazing that they can use their roots and their needles to get enough water.
Welp, see you later!
I want to take a closer look at some of the leaves growing on the trees outside!
Even if they aren’t redwood needles, maybe they’re doing something amazing, too!
Bye, Jessi!
Bye everybody!
Bye, Sam!
I’m so glad that Sam is having fun learning about redwoods.
If you’d like to keep discovering more about redwoods and all things science
with all of us here, make sure to hit the subscribe button below.
We’ll see you next time, here at The Fort.
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