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Go to Brilliant.orgSciShow to learn how you can take your STEM skills to the next level. [ intro ]. Have you ever cut into a bell pepper and found another pepper inside it?

Cause I have. It's like someone took a baby pepper and put it inside a bigger one. I thought it was, like, a bug at first.

Well, I have some good news: that mini pepper is totally edible. It's just a potential seed that got a little carried away. You see, the seeds inside fruits like peppers start out as ovules: the plant version of egg cells.

During the flower stage, they wait for sperm inside a structure called the carpel— the outer part of which actually becomes the pepper fruit. You get a pepper when pollen ends up on the top of that carpel. The sperm in that pollen travel down to the ovules and fertilize them, and that triggers the ovules to become seeds and the outer part of the carpel to become fruit.

But there are lots of ovules in a pepper and not all of them get fertilized. Sometimes, an unfertilized ovule goes rogue and starts to become a new pepper instead. Or, part of one anyway.

See, that inner pepper is actually a wanna-be carpel, or what botanists call a carpelloid structure. Basically, genetic mutations can cause an unfertilized ovule to start growing like it's that outer part of the carpel. It just… starts making a fruit!

Since this happens without the ovule being fertilized, these internal peppers are considered a type of parthenocarpy: the development of fruit without fertilization. And they're more common in peppers with genetic mutations that create misshapen ovules— ones which can't be fertilized properly. Right now, no one really knows exactly why this is, but researchers are eager to find out, because strains of pepper that produce carpelloid structures sometimes make entirely seedless peppers.

That's right — parthenocarpy doesn't just give us nested fruits, it can produce completely seedless ones!... something that we have taken advantage of. Bananas, pineapples, eggplant, and oranges are just a few varieties of seedless parthenocarpic fruits that we enjoy on a regular basis. And while pepper seeds might seem benign, plants that make seedless pepper fruits tend to be more reliable and make consistently larger peppers, so they'd mean a better harvest.

We're also not the only ones that benefit from parthenocarpy. Some wild plants use it as a way of dealing with predators. Like, wild parsnips.

They will produce some fruits with seeds and some without. The seedless ones are decoys for parsnip webworms: pests which eat and destroy the plant's seeds. They tend to attack the seedless fruits instead of the ones that contain the plant's actual offspring!

So parthenocarpy is a useful phenomenon, both as a natural defense and for our own snacking purposes. And yes, even though that tiny pepper isn't fertilized, it's a pepper all the same, which means that it is totally edible. Chop it up and put it in your taco.

Just think of it as, like, a two for one special! And if you love good deals, then I have more good news. Today's sponsor, Brilliant, is offering 20% off their annual premium subscription to the first 200 people to sign up at Brilliant.orgSciShow!

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