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Alright, so we all know that person who, every time you say anything, they're like "actually, technically, tomatoes aren't vegetables." And, I just, before we do this episode I would like to encourage you to not be that person, but knowing the real classification of the stuff that we eat can tell you a lot about where fruits and vegetables come from and how their developed. So it's pretty interesting, just don't use it to be an insufferable pedant. 

For example, officially speaking, anything that is a root, stem, or leaf of a plant qualifies as a vegetable, meaning that some things you might ordinarily consider a fruit, it's actually a vegetable.

Rhubarb, for instance, we think of kinda like a fruity thing because it's in pies and it tastes all sweet, but it's the stalk of a plant, so it's a vegetable. Vegetable pie, who would have thought of that.

Corn, zucchini, and green beans, on the other hand, all fruit. So are tomatoes, and that's because these foods are not roots, stems, or leaves. They're ovaries. Hopefully that doesn't make you feel too weird. 

So yeah, fruits are the ovaries of a flowering plant that develop after its seeds are fertilized or, sometimes, after they've been triggered to develop without fertilization. From the plant's perspective, surrounding its seeds with something soft and juicy and delicious increases the chance that those seeds will be eaten and then spread around in nice, fertile piles of poo.

So broccoli and cauliflower are not fruit even though they are flower buds because they're unopened; the flower hasn't transformed. True fruits come in lots of different types and some of them make for excellent anatomy lessons.

One key factor for botanists in categorizing fruits is how many ovaries the flower had, so berries, by definition, are fruits that come from a single ovary with multiple seeds. That makes grapes, bananas, peppers, and tomatoes all different types of berries.

But hold on to your shorts because raspberries and blackberries are something totally different called aggregate fruits, a whole bunch of little fruits grouped together. And strawberries aren't berries either, in fact the tasty red part of a strawberry isn't even a fruit. It's a special kind of plant structure called a fleshy receptacle. You actually have to look much closer at the receptacle to see the fruits which are called achenes. They are dry, one-seeded fruits that speckle the red surface of a strawberry.

Sunflowers produce another achene which you probably know as sunflower seeds. Nuts are fruits, too, and their shells, or coats, develop from the ovary wall. That includes things like chestnuts and hazelnuts. But technically, walnuts and pecans are not nuts, along with other single-ovary fruits like peaches and plums and coconuts, they're called drupes.

Drupes only have one seed with a distinct skin covering a fleshy middle layer. In a drupe, the inner layer is often called stone-like, and if you've ever accidentally chomped on a peach pit you understand why. 

Now if you want to get super fancy with your botanical terminology, raspberries and blackberries are specifically aggregate drupes,and each small section is called a drupelet. But many fruits are more than just a ripened flower ovary.

Take pome fruits, for instance, like apples and pears. Pome fruits are known as accessory fruits because there's so much more going on in them than a simple ovary. The ovary makes up only the core of the fruit. The flesh of the fruit is actually modified flower petals and sepals, the flower parts that cover a bud, and even a knobby receptacle at the base of the flower.

And when you eat hesperidium fruits you're also getting a mouthful of the unexpected. This category includes fruits with tough rinds and little partitions like limes and grapefruits and oranges. Turns out that those small packed-together juicy bits in each section called juice sacs were once tiny hair-like cells on the inside of the ovary but they filled the busting with goodness as the fruit ripened. So the next time you enjoy your pulpy glass of OJ enjoy your mouthful of fruit-hair.

Thank you for watching this SciShow dose which was brought to you by our patrons on Patreon, who allow us to explore the weird majesty of fruit science. If you want to get behind the scenes pictures or blooper reels or other cool stuff you can go to patreon.com/scishow, and if you want to keep getting smarter with us you can always, please, go to youtube.com/scishow.

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