Seeds. Potent little packages of genetic material. You bury them in the ground and miraculously they grow food. And that food gives you new seeds. And the circle continues, and you never ever grow hungry again.
But what about seedless fruits and vegetables? Is this genetic modification? Grapes, watermelon, citrus, cucumbers. These were foods that had seeds in them when I was a kid. But now you go to the grocery store, at least here in the United States, and most of them are seedless.
So how? Let me just say right off the bat that we’re not dealing with GMOs here. You know, genetically modified organisms. Those are foods whose genetics are manipulated by scientists in ways that can’t occur in nature. Seedless plants are not common in nature, but they do exist. It’s called Parthenocarpy. And there’s actually a clue in the name. Where are my Greek scholars? It comes from Parthenos, which means virgin, and Karpos, meaning fruit. Virgin fruit means fruit grown without fertilization. And this gives you seedless fruit.
Okay, a quick recap on what fertilization actually is. If you think back to almost every How Does It Grow episode, we discover how farmers bring in bees to help pollinate their fields. As the bees buzz from plant to plant, they transport pollen and drop it on the female parts of the flowers. And those fertilized ovaries grow into fruit. And that fruit contains seeds.
Now get this. There are plants that can grow fruit without that transfer of pollen, including certain kinds of cucumbers. Seedless cucumbers are Parthenocarpic. They can grow fruit without fertilization. But it’s not all easy-peasy.
If you’re a farmer who wants to grow seedless cucumbers, you don’t grow them in an open field like you do seeded cucumbers, like the ones you saw in our How Does It Grow episode. You put those Parthenocarpic plants in a greenhouse. You lock them up. If a pollinator happens to drop some pollen and fertilize a flower, it will grow into a seeded cucumber, which totally defeats the purpose.
Okay, so we’ve got Parthenocarpy, an unusual but naturally occurring genetic condition. Well, there’s another one. Stenospermocarpy. Are you with me? Stenospermocarpy gives us seedless grapes. This is when the plant is pollinated and fertilized. Seed development begins. But the plant aborts the process before the seed matures. That’s why you’ll find tiny, soft, ghost-like seeds inside your grape instead of big, crunchy, bitter ones like you find in seeded varieties.
Now, in the case of seedless citrus fruit, farmers are basically outsmarting their trees. Lots of citrus trees can’t produce fruit with seeds inside of them unless their flowers are fertilized with pollen from a genetically different variety. So say there are two cara cara orange trees standing next to each other. They can’t pollinate each other and produce fruit with seeds inside. They’ll produce fruit, but fruits without seeds inside. See that?
So farmers looking to grow seedless fruit will grow entire orchards of just one single variety. And as we saw in our orange How Does It Grow episode, that means farmers are actually planting clones. Clones? Breathe, this is just good old-fashioned genetic selection. See, for millennia, plant breeders have chosen plants for different traits, like sweetness or color or hardiness, and they’ve hand-pollinated the plants to create new varieties of their choosing.
In the case of fruit like citrus, grapes, apples, bananas, cuttings are taken from these new varieties, and those cuttings, which are basically baby clones, are planted instead of the seed to ensure the fruit is exactly what the farmer wants.
I took a deep dive into this in our apple How Does It Grow episode, and you can check out that one and all of the episodes I’ve mentioned by clicking on the links in the description below.
You know what’s kind of crazy to think about? For thousands of years, we were eating watermelons and grapes and other fruits with seeds, and just in the last decade or two, the popularization of seedless varieties has made it actually difficult to find varieties with seeds.
Now I know that’s not the case in many parts of the world, but it is here in the US where it seems like for better or worse convenience conquers complexity of taste. That especially goes for seedless watermelon, but seedless watermelon is a whole other can of worms. In fact, it’s so unique, I dedicated an entire video to it, and amazingly you beautiful nerds really seem to dig it. If you haven’t checked it out, click that little banner thing up there.
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