The world of plants may seem quiet and calm.

But you don’t need to go much farther than your front door to find drama afoot. Like, that sweet, summery scent of freshly cut grass?

It’s actually the plant  equivalent of a scream. Through chemicals, grass is sounding a warning call to nearby plants, which start putting up their defensive dukes, getting ready to protect themselves from damage. And plants are smart.

They can tell the difference between mechanical damage, like that lawn mower, and being chomped by an insect. If bugs are attacking, plants can release special chemicals  that yell to other bugs nearby, "Please come eat whatever's eating me.” So your quiet, summer afternoon has just turned into a plant action movie, complete with elaborate fight sequences. We humans think we’re such a big deal, but if you squished up every living  thing on the planet into one big ball, eighty percent of it would be plants, and less than one percent would be mammals.

Some folks say we’re missing the forest for the trees, but we’re also missing the trees! And the ferns, and the mosses, and the palms and the sedges. There’s a whole other world here, and it’s all around us.

You see, plants aren’t just a bunch of wallflowers. You just weren’t a part of their group chat yet. But that’s all about to change, and they have so much dirt to dish out.

Hi! I'm Alexis, and this is Crash Course Botany. [THEME MUSIC] Botany is the scientific study of plants. That includes the huge ones, like towering 300-foot tall coastal redwood trees, and the tiny ones, like Wolffia globosa: green globs the size of a candy sprinkle. It includes the tasty plants, like sweet corn and mangoes; the super-stinky plants, like the corpse flower; and the super-stinky and tasty plants, like the durian.

There are plants that look like brains, plants that look like rocks, even plants that look like Demogorgons. Botany is all about this kaleidoscope of plant life. It’s the science of plants’ structure and their function, the way their parts work and how their genetic traits pass on.

But it’s also about plants’ relationship to other living things, including us. And it’s no overstatement to say our lives —and the lives of every other creature on Earth— depend on plants. You’ve probably heard of photosynthesis, the chemical process that plants use to turn water, sunlight, and carbon dioxide into energy for them to live on.

Well, the oxygen that comes out of that process is a byproduct, or something that’s made by  the nature of the process, not on purpose. And that incidental byproduct just happens to be the thing we evolved to breathe. Which, when you stop to think about it, is pretty amazing.

Plants also cycle water and nutrients that all living things need between the soil and the atmosphere and back again. Even a single tree can be an all-in-one bed-and-breakfast for dozens of organisms. Like a fully alive combination Airbnb and Taco Bell.

In fact, once you start noticing how deep this “plants are connected to everything” business goes, it’s hard to stop. Plants are not just in your garden or your bathtub or the woods behind your house. They’re in nearly everything.

Let’s head to the Thought Bubble… From the moment you wake up, you’re already in touch with plants —because you spent all night wrapped up in sheets made of cotton fibers. Stumble into the shower, and plants are there, too. You grab a luffa, which is actually a dried-out tropical gourd.

Give yourself a scrub and you come out smelling like a rose —because the oils in your soap came from roses. Your toothpaste contains cellulose gum, the same stuff that plants’ cell walls are made of. And it’s spiced with a little flavor from a mint plant.

Your floss glides against your gums with the help of carnauba wax, which comes  from palm tree leaves. And when you spot a little volcano erupting on your chin, you dab on some acne medication. It’ll work its magic thanks to oil from the Australian tea tree.

You’re running late by now, but there’s still time to get some breakfast. The kitchen smells like freshly-brewed coffee, made from beans of the Coffea plant, and you grab some avocado toast —a combo of wheat grown to be pest-resistant, spread with the insides of a big, green, buttery berry. Triple-threat that you are, you grab your baseball bat (made from a maple tree), your clarinet  (made from an African blackwood tree), and your lines for the play (printed on paper from a pine tree).

And don’t forget to dodge falling acorns on the way out. This is a plant’s world; you’re just living in it. Thanks, Thought Bubble.

For most of humans’ time on Earth, we gathered plants from the wild. See a berry, eat a berry. Find some tubers, share ‘em with your friends.

But around ten thousand years ago, some of us struck up a deal with plants: “Hey, we’ll stash your seeds and help you grow on purpose. In return, give us food we don’t have to wander for.” This alliance with plants was a history-bending, society-shaping big deal. It changed how people related to food and to each other, turning some people into farmers and some plants into crops.

Which, in the case of teosinte’s transformation into corn, was a major makeover. We call it the Neolithic Revolution. Agriculture turned small, mobile groups of people into big, permanent settlements, where more food was grown, supporting more people.

Soon those people started splitting up work, so only some people were in charge of growing food while others became shopkeepers, restaurateurs, and YouTubers. And, over time, this allowed human populations to grow dramatically. Eventually, thanks to the powers of agriculture and transportation combined, people could choose to live in cities or rural areas, because foods could be predictably produced and moved to people, instead of people moving to them.

So agriculture is a big part of the plant-and-people story. But there are lots of other ways we’ve used plants: as medicines and poisons, in our clothes and shelter. And the big field of botany is shaped by  diverse ways of relating to and knowing plants.

Like, all over the world, Indigenous Peoples have passed on generational knowledge of plants local to them. For example, the Hidatsa gardener Maxi’diwiac, also known as Buffalo Bird Woman, helped record her tribe’s ways of growing corn, squash, beans, and sunflowers in the early 1900s— using practices gardeners still follow today. Botany has also been shaped by the knowledge of enslaved people throughout history, like Edmond Albius.

In the 1840s, when Albius was only twelve years old and enslaved on the island of Réunion, he invented a way of pollinating vanilla plants by hand, making it possible to grow them profitably. Albius was freed a few years later, when slavery was abolished on the island. To this day, vanilla growers still use his techniques.

People like Maxi’diwiac and Albius had a secret weapon in their arsenal: close observation and knowledge of plants. And anyone can develop it, in the form of botanical literacy. That’s information that helps you read the language of the plant world and understand the science surrounding it.

Like, remember when I said plants use sunlight for photosynthesis? Well, the leaves of “living stone” plants found mostly in hot, dry areas of Africa, act like fiber optic cables— they bring sunlight underground so that the plant can perform photosynthesis where it's cooler. Or another thing speaking the language of plants lets you in on: some orchids can produce bee-shaped flowers— which fake bees out so that they’ll pollinate  what they think are potential mates.

With botanical literacy, you can also give an appropriate amount of side-eye to a package of Himalayan salt that’s labeled “not genetically modified.” Genetically modified organisms, or GMOs, are living things with genes that have  been altered in ways that don’t happen in nature. Like, scientists have created insect-resistant GMO crops by giving them genes from soil bacteria — genes they wouldn’t be able to obtain  just by breeding with other plants. So that non-GMO salt label …doesn’t make sense.

Because salt is a mineral, not a plant or an animal, and has no genes to modify to begin with. We’ll be getting more into GMOs in a later episode. The point is: botany is about much more than knowing your begonias from your bougainvilleas.

Although that part can be fun, too. But if you’ve never really noticed  plants before, you’re not alone.  [TV static] Do plants just fade into the background for you? Because they’re mostly green, do you tend to lump their features together into a solid wall of color?

Are you, like other humans, drawn to things that move and look like you? Well, you might just have plant awareness disparity. The cure is watching Crash Course Botany.

So, yeah, plants are like… the elephant in the room. Even that phrase doesn’t reference plants. Can we coin a new version?

When something’s like right in front of  you, but no one’s talking about it, let’s call it “the bamboo in the room.” “The tomato in the room?” “The giant redwood in the room.” Because when we don’t take heed of the bustling community of shoots, vines, and leaves around us, we allow sneaky false assumptions to take root instead. We start to think things like, “Plants don’t do anything,” or “Humans are running this show.” But if you’ve ever broken out in welts from brushing against poison ivy, or seen a telephone pole swallowed up by a Kudzu vine, well, you know plants do things. And we’re not as in control as we think.

The truth is, plants do perceive and react to the world around them —just not in the ways people do. They have their own ways of communicating and sensing information, which botany can help us tune into and understand. Like, plants can’t move when a threat is around.

But they can share information about incoming danger. When a plant isn’t getting enough to drink, for example, tiny openings on its leaves called stomata start to close up to conserve water. Signals about their stressed state can pass to any neighboring plants that touch roots, so those plants know to prepare for drought by closing their stomata, too.

Botanists only recently learned —and are still learning— about how roots allow plant communication to happen just beyond our perception. So if you haven’t thought much about plants yet, there’s still time. They’re waiting for you.

And possibly gossiping about you. To find out, you need to get in the group chat. It can be easy not to pay plants much notice in everyday life.

But you’re connected to them all the same. Without plants, you wouldn’t  just not have hot cocoa or chalupas— you wouldn’t be alive. None of us would be.

And there’s much to be gained by turning your attention to plants. Plants shelter us, clothe us, medicate us, feed us, and oxygenate us. We’ve structured our  civilizations around them, and they, in turn, make life possible for us and other organisms.

By studying plants, we can understand forces that shape our lives— and tune into the quiet communication that’s happening all around us. Let’s start learning some of plants’ secrets. Hey, before we go, let’s branch out!

Chewing gum was first invented using chicle, a substance that comes from what kind of tree? If you head down to the comments ASAP, I’m sure you’ll find the answer!  Thanks for watching this episode of Crash Course Botany which was filmed at the Damir Ferizović Studio and made in partnership with  PBS Digital Studios and Nature. If you want to help keep Crash Course free for everyone, forever, you can join our community on Patreon.