Vascular Plants = Winning! - Crash Course Biology #37 - Lake Harding Association

Vascular Plants = Winning! – Crash Course Biology #37

Vascular Plants = Winning! – Crash Course Biology #37

By Micah Moen 100 Comments August 14, 2019


This is yarrow, a flowering plant found all over
the Northern Hemisphere. Its feathery leaves have
natural astringent properties, and its scientific name, Achillea,
comes from Achilles, the Greek hero, who is said to have used
it on the wounds of his soldiers. And this is snakegrass, also known
as horsetail or, to the kids, popgrass, because you can
just pop it apart, and then put it back together again. Although
on top there, it’s dead now. And this is a ponderosa pine,
one of my favorite trees. They can grow hundreds of feet tall, and on a warm day if you sniff
it, it smells like butterscotch. They all have different
shapes, sizes, and properties, but each of these things is a
vascular plant, one of the most diverse and, dare I say, important
families in the tree of life. Since their predecessors first
arrived on the scene some 420 million years ago, vascular
plants have found tremendous success through their ability to
exploit resources all around them. They convert sunshine into food.
They absorb nutrients directly through the soil without the
costly process of digestion. And they even enlist the help
of some friends when it comes to reproduction, so often when
they’re doing their thing it involves a third party.
Which, y’know, good for them. But these things alone can’t explain vascular plants’
extraordinary evolutionary success. I mean, algae was photosynthesizing long before plants
made it fashionable. And as we learned last week,
nonvascular plants have reproductive strategies that are tricked
out six ways from Sunday. So, like, what gives? The secret to vascular plants’
success is in their defining trait: conductive tissues that
can take food and water from one part of a plant
to another part of a plant. This may sound simple enough,
but the ability to move stuff from one part of an
organism to another was a huge evolutionary breakthrough
for vascular plants. It allowed them to
grow exponentially larger, store food for lean times,
and develop some fancy features that allowed them to
spread farther and faster. It was one of the biggest revolutions
in the history of life on Earth. The result? Plants
dominated Earth long before animals even showed up. And even today, they hold
most of the world records: The largest organism in
the world is a redwood in Northern California,
115 meters tall. Bigger than 3 blue whales
laid end to end. The most massive organism is a
grove of quaking aspen in Utah, all connected by the roots, weighing
a total of 13 million pounds. And the oldest living thing? A patch of seagrass
in the Mediterranean dating back 200,000 years. We’ve spent a lot of
time congratulating ourselves on how awesomely magnificent and
complex the human animal is, but you guys, I gotta
hand it to you. So you know by now, the more
specialized tissues an organism has, the more complex they are
and the better they typically do. But you also know that these
changes don’t take place overnight. The tissues that define vascular
plants didn’t evolve all at once, but today we recognize three types that make these
plants what they are. Dermal tissues make up their outermost layers and help
prevent damage and water loss. Vascular tissues do all of that conducting of materials
I just mentioned. And the most abundant
tissue type, ground tissues, carry out some of the most
important functions of plant life, including photosynthesis
and the storage of leftover food. Now, some plants never
go beyond these basics. They sprout from a germinated seed, develop these tissues,
and then stop. This is called primary growth,
and plants that are limited to this stage are herbaceous. As the name says,
they are “like herbs” small, soft and flexible, and
typically they die down to the root, or die completely,
after one growing season. Pretty much everything you see
growing in a backyard garden: herbs, flowers, broccoli
and that kind of stuff, those are herbaceous. But a lot of vascular plants
go on to secondary growth, which allows them to grow
not just taller but wider. This is made possible by the
development of additional tissues, particularly woody tissues. These are your woody
plants, which include shrubs, bark-covered vines called lianas,
and of course, your trees. But no matter how big they
may or may not grow, all vascular plants are organized
into three main organs, all of which you are intimately
familiar with, not just because you knew what they were when
you were in second grade, but also because you probably
eat them every day. First, the root. It absorbs
water and nutrients, and serves as a pantry of
leftover food, and of course, keeps the plant anchored
in the ground. Next, the stem. It contains
structures that transport fluids, stores nutrients, and also is
home to specialized cells called meristems that are
responsible for creating new growth. But their most important task
is to support the last organ: The leaf. This, of course,
is where the plant exchanges gases with the atmosphere and collects
sunlight to manufacture food, with the help of water and
minerals collected through the root and sent up through the stem. Now, each of these organs
contains all three tissues, which together work to
absorb, conduct, and exploit one of the world’s most
important molecules: water. So, since plants are pretty
much designed around water, let’s follow some H2O to see
how plants make the most of it. First, as with most organisms,
nothing can get in or out of a plant without getting past the skin,
in this case the dermal tissue. In smaller, non-woody plants,
most of this is just a thin layer of cells called,
fittingly, the epidermis. Naturally, this is great for
keeping the outside out and the inside in, but the
epidermis can also sport some snazzy features in
different parts of the plant. In leaves and stems, for example,
it often has a waxy outer layer called a cuticle that
helps prevent water loss. On some leaves, or on pods
that hold those valuable seeds, the epidermis can sprout hairlike
structures called trichomes that help keep insects at bay and
secrete toxic or sticky fluids. The same secretions that make
the yarrow useful for first aid, for instance, are
also what discourage ants from using it for lunch. Finally, in the roots, the epidermis
has similar features called root hairs that maximize the root’s
surface area for absorption, just like we’ve seen in
our own organ systems. This, of course, is where the plants
generally absorb the water they need. By the way, the cells that
make up this dermal tissue are the most basic, essential
building blocks of vascular plants, called parenchyma, or
“visceral flesh,” cells. These are the most abundant plant
cells, found not just in roots but also in stems,
leaves, and flowers. They’re thin and flexible
and can perform all kinds of functions depending
on their location. Now, after passing through the
skin of the root and through its starchy cortex, or outer layer,
water arrives in the first of two kinds of vascular
tissue: the xylem. The xylem’s main function is
to carry water and dissolved minerals from the root
up to the leaves. But, like, how?
How, by Zeus’ beard, can plants make water defy gravity? Well, a lot of the reason is that,
up top, the plant is continuously evaporating water through a
process called evapotranspiration. As water evaporates from the
leaves, which I’ll explain in greater detail when we get
up there, it creates negative pressure inside the xylem,
which draws more water upward. Plants can transpire truly
staggering amounts of water, and it’s because of this that
our atmosphere is habitable. A single acre of corn gives
off about 3,000 gallons of water every day.
A large oak tree, just one tree, can transpire 40,000
gallons in a year. Only 1% of the water that plants
absorb is actually used by plants, mostly in photosynthesis. The rest is slowly, and invisibly
released, providing one of Earth’s most crucial functions,
transporting water from the soil into the atmosphere,
where it then returns to the surface as rain, making
all life possible. Yeah. Chew on that as we
continue up the xylem. And as we get higher in the
plant, we begin to encounter a greater diversity of cells,
designed not only for moving stuff around but also for
providing structural support. For instance, elongated cells
with thicker cell walls, called collenchyma, help hold
up the plant body, especially in herbaceous plants and young
structures like new shoots. Celery is mostly made
up of these cells, so you already know
what they taste like. In larger, woody plants,
you also find sclerenchyma cells, especially in the xylem. These have even thicker cell
walls made from lignin, a super-strong polymer
that makes wood woody. What’s weird about
sclerenchyma cells, though, is that most of them when they
reach maturity, they die. They just leave behind their
hearty cell walls as a support structure, and new cells form
a fresh layer during the next growing season, pushing the
old, dead layer outward. In warm, wet years these layers
grow thick, while in cold, dry years they’re light and thin. These woody remains form tree
rings, which scientists can use not only to track the age
of a tree but also the history of the climate
that it lived in. Now, at the top of the
xylem, water arrives at its final destination: the leaf. Here, water travels through an
increasingly minuscule network of vein-like structures
until it’s dumped into a new kind of tissue
called the mesophyll. As you can tell from its
name, meso meaning “middle” and phyll meaning “leaf,”
this layer sits between the top and bottom epidermis
of the leaf, forming the bacon in the BLT that
is the leaf structure. This, my friends, marks our
entry into the ground tissue. I’m sure you’re as excited
about that as I am. Despite its name, ground tissue
isn’t just in the ground, and it’s actually just defined
as any tissue that’s either not dermal or vascular. Regardless of this low billing,
though, this is where the money is. And by money I mean food. The mesophyll is chock full o’
parenchyma cells of various shapes and sizes, and many of them are
arranged loosely to let CO2 and other materials flow between them. These cells contain the
photosynthetic organelles, chloroplasts, which as you know
host the process of photosynthesis. But, where is this CO2 coming from? Well, some of the neatest
features on the leaf are these tiny openings in
the epidermis called stomata. Around each stoma are two
guard cells connected at both ends that regulate its size and shape. When conditions are dry
and the guard cells are limp, they stick together,
closing the stoma. But when the leaf is flush with
water, the guard cells plump up and bow out from each other,
opening the stoma to allow water to evaporate and let
carbon dioxide in. This is what allows
evapotranspiration to take place, as well as photosynthesis. And you remember photosynthesis:
Through a series of brain-wrackingly complicated reactions sparked
by the energy from the sun, the CO2 combines with hydrogen
from the water to create glucose. The leftover oxygen is
released through the stomata, and the glucose is
ready for shipping. Now, if you’ve been paying
attention, you noticed that earlier I said that there are two
kinds of vascular tissue, and here the circle is
made complete as the sugar exits the leaf through the phloem. The phloem is mostly made
of cells stacked in tubes with perforated plates
at either end. After the glucose is
loaded into these cells, called sieve cells or
sieve-tube elements, they then absorb water from
the nearby xylem to form a rich, sugary sap to transport the sugar. This sweet sap, by the
way, is what gives the ponderosa its delicious smell. By way of internal
pressure and diffusion, the sap travels wherever it’s
needed, to parts of the plant experiencing growth during the
growing season, or down to the root if it’s dormant, like during winter,
where it’s stored until spring. So now that you understand
everything that it takes for vascular plants to succeed, I hope you
see why plants=winning. And I’m not just talking about
them sweeping the contests for biggest, heaviest,
oldest living things. Though, again,
congrats on that, guys. Plants are not only responsible
for, like, making rain happen, they’re also the first and most
important link in our food chain. That’s why the world’s
most plant-rich habitats, like rain forests and grasslands,
are so crucial to our survival. When those habitats
change, everything changes: weather, food supply, even the
incidence of natural disasters. So I, for one, welcome our plant
overlords, because they’ve done a great job so far,
making life on Earth possible. But, I know you’re curious,
how do different kinds of plants make more plants? That’s all
about the birds and the bees, which is what we’ll be
talking about next week. Thank you for watching this
episode of Crash Course Biology. And of course, thank you
to everyone who helped put this episode together. If you want to review anything,
there’s a table of contents over there, just click, and you
can go see the part of the episode that you want to
reinforce inside of your brain head. And if you have any questions,
we’ll be on Facebook or Twitter, or of course, down
in the comments below. And we’ll see you next time.

100 Comments found

User

Azzy Moore

Cramming at the last minute

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nyi lever

Was the vascular system the same a billion year ago?

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Jazzi Mae Villablanca

do you have app for offline users?

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K

I am not supposed to be watching this, I'm not – I'm not! I should be studying for Physics. I cannot help it.

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mSCI

Great video as usual, but isn't a huge fungus in Oregon the largest organism in the world, not a redwood tree? I think you said that in your fungus video.

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Neonas Rock

Oddly made me hungry

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Flaming Ravie

I’ve been attending a science class and the topic was vascular plants. Thanks for giving me an idea!

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Bob Vesting

You are the man u take something so mine nummin and make it fun …the only thing just please slow down a bit …but ty for not make it a snore fest

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Stacy Fisher

Running through crash course 2018

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Shah Consulting

this immature white man demeans Biology by presenting lessons in Biology in such a geeky and moronic manner! he should be taken out and made to collect garbage instead.

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ice cream

So effing tired of comments like "you talk too fast please speak slower" on Crash Course vids

For the last time people you CAN adjust the speed in the settings!!!!

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ice cream

Stop scrolling and concentrate on what Hank's sayin'!!

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Ano N. Ymous

Dicots have vessels and tracheids and monocots lack vessels, how come the tallest tree is a monocot? What's their secret?

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Chrissen Gemmill

vascular plants are not a FAMILY!

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h

That wasn't yarrow

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Luar Zaragoza

"smells like butterscotch"

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Anne-Marie Robinson

It would be great if these came in a downloadable audio format… Like a Podcast. Great review for when I'm biking to school or walking the dog or even just making lunch in the morning before a big test.
Cheers,
Anne-Marie

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ask.exe_has_stopped_working

I hope this counts as studying for my Biology exam

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Ellie Sullivan

I basically owe my entire biology degree to crash course

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alex smith

I'm not kidding when I say this channel literally saves my high school career.

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Arunabh Mishra

Awesome man!

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Joseph Acho

He looks like someone who got bullied as a child and was beaten by his parents. Just saying

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Milo Parker

Actually love how you talk fast btw, cause aint nobody have time for a droning voice.

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Elizabeth Picado

Please make a type of fruit video… for example drupe, berry etc

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Tayyaba Nudrat

GREAT ITS REALLY FUN SEEING CRASH COURSE THAN STUDING THROUGH BOOKS

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The Writer Artist Potato Nerd

Lol its dead on top.

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dRONGO

You made Biology fun…I thought that was impossible! YOU GET A LIKE FROM ME! 🙂

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Farya Arshad

conductive tissues take food and water from one part to another
meristems create new growth, support leaf
leaf gas exchange occurs
waxy outer layer cuticle in epidermis, helps prevent water loss
cells that make dermal tissue are parenchyma
negative pressure inside the xylem as water evaporates which draws more water upward
collenchyma help hold up plant body
ground tissues have chloroplasts
glucose is loaded into sieve cells (phloem)

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User

Minisushi 1212

112 non vascular plants disliked this video

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inbox0000

Wix are annoying hipster cheeseballs

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User

N&W 2156 Y6a

butterscotch pine

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Ovid Osophire

he squashed his nose on the tree in the beginning and it made me laugh so hard

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Katrina Garcia

Tony rodriguez

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Nashra Bodoraya

“A kill ya” plant Achilles used to heal wounds of soldiers 😂😂😂😂😂

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Omeesha Krishnan

WARNING , CAUTION : trypophobia triggers in this video ( and generally this whole section of biology)

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Daniella Collison

if only you were my lecturer at uni!!!

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Aksh Jain

I can't say how to react after seeing this video.Really awesome😎😎😎😎😎

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User

Mazhar Abbas Bukhari

sir u can copy trump too well ,also try it

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Happy Cat

As Hank started to express appreciation for plants toward the end of the video I was just like, I want to date this person.

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Matthew Niedbala

Stop with the yarrow lol

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Charlestone 17

LMAO AT 2:08 why is there a largemouth bass in the "Mediterranean Sea"???

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Maggie ambrosino

Hank you are the best Too many other foreign commentators too hard to understand or others too slow. You make it all make sense!!

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Rica Rants

Why does some of the plant parts sound like our body parts?

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Nisha Trivedi

nice vedio and nice information about plants

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Trishal Muthan

Damn so basically we got lucky af

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José Carlos Quispe Barreto

Amazing video and remarkable effort¡¡ <3

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Elizabeth Iyambo

damn you good..I have been missing out a lot. from now on, I'm aiming for As.

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haley foard

great video!

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ibrahim nazir

I'm a plant and I love this video ,I wood love to be featured in the next one

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Fardin Khan

Non-Vegans be like: ( ͡◉ ͜ʖ ͡◉)

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User

Garrett Lacey

Bark covered vines are called what? Thanks.

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J Evans101

Beastly introduction as always :O

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PaulEx

That's not yarrow. It's something in the carrot family.

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jay stick

I think it’s actually the Jeffrey pine that’s scented. Usually the areas where ponderosa grow are logged and the Jeffrey survive because they shouldn’t be milled. They are too flammable. They are almost identical. Almost.

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rainman

wow

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katie bishop

bouta fail my plant midterm tomorrow np tho

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hob

You have no clue how grateful I am for these videos they help me to understand bio from a different voice and you're so entertaining as well. Thank you Hank :")

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wareesha nadeem

throw a like ……….hanks a great man in bio

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DangerHevezi

Uneven shave

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gamer text

Im in class 7 and this topic is in my syllabus

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Miranda No Michi

I’m not even in school currently, but I always find myself watching these videos ❤️

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Xavier

Plants = winning – Vegans = losing.

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Princess Pinto

ah yes the super strong cells made from ligma

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swati karia

root hair is the extension of epidermal cell

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Blazepowder69

is there a buzz tree ?

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VampireDucks

The largest organism in the world is actually not a redwood or any other plant. It's a fungus. The giant honey mushroom in Oregon.

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Lizzy Siglin

1:18

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kamilladoc

Thanks man

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James Foster

You are awesome

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Aybüke Gökçe Yavaş

They teach this stuff to us in our seniour year. (Yup, I mean in highschool). I have been trying to find a decent vid on the subject but I couldn't find it in my language which is Turkish. This vid just saved my life for real. The final exam, here I come!
Thank you for the vid!

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Umakant Yadav

Kya bol rhe ho yar

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Andrew J.

So vascular weeds first appeared 420 million years ago? Nice.

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Ethan Vance

Two things: One, I don't like when he says "by Zeus's beard" because nothing in Greek mythology actually happened. Two, EVOLUTION NEVER HAPPENED!!! God created everything how it is now.

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Chastelle Bennett

At 1:08 there is a typo, should say “non vascular plants”

Still love you though Hank!

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Matiko Tiko

what a nice explanation

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poppy

I don’t get this shet

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Name Here

Sclerenchyma cells in wood (fibers and tracheary elements) proper do not get pushed out when new wood layers form. They remain inside the stem.

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maf m

I love your videos they are funny and easy to understand I love watching your videos to study science

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Suraj Swamynathan (student)

Does anyone have a fully labeled leaf cross-section?

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Tina Ayne

these videos got me through high school and now they're getting me through uni

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Nina Charlery

I love it.😄😄😄😄

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Jamaiya Penn

loved this scenery!!

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Tasnem Hatem

How can plant in the sea breathe??

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Tasnem Hatem

Plz answer me I have an exam and can u pkz hurry n making the new vd cuz I hava an exam next week 2 😭😭♥️

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William Churchman

anyone else here in 2019? XD

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Kerry Kingsley

I heard that the largest organism in the world was a fungus, not a redwood.

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Khizer tutorial tv

This is a good method of teaching.
I want to adopt in my videos
Nice sir.

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Juan Pablo Pedroza

Wow, pressure differences cause the water in the plant to defy gravity and move up? I wish pressure could do the same to my grades.

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Ethan Raughley

actually it smells like vanilla

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Magic Music

I've almost watched all 40 videos in preparation for my biology keystone test.

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E G F

Slow the F down!

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Richard

Last time I’ll ever watch a crash course vid as I have my final exam tomorrow. Just wanted to say thanks for helping me through my entire A level without you guys I would’ve definitely failed

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Nada Farouk

can you explain more about the structure of dermal ,ground and vascular tissue ?

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Patricia McGeorge

0:42 420MYA hehe

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Jason14500 A

Have a blessed

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Bangdon Solo

Sea grass living that long…. seriously

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LittleErn Wise

Great vid, thanks for making it.

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Abi Rosyidah

What a fresh video…. Soooo biologic

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Nathan Krause

were are you at to have the ponderosa trees smell like butterscotch here in Arizona they smell like vanilla

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Swapnil Patil

Much more in less time you complete 45 min lecture in just 10 min and saving my time⏳⏳⏳

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