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You are watching: Are strawberries the only fruit with seeds on the outside

“Why perform strawberries have their seeds on the outside, instead of ~ above the inside?” that was the question one of my daughters asked recently. I had actually no idea, so I got to out to kris Gunter, an associate professor that horticultural scientific research at NC State. And also the answer surprised me.

First off, strawberries don’t keep their seeds exterior their fruit. Those points we think of as strawberry seeds aren’t seed – and the big, red strawberry “fruit” isn’t technically a fruit.

In “true” fruits, prefer peaches*, a flower is pollinated and then the flower’s ovary swells and also becomes the fruit, through the particle or seed in the middle.

Not so v strawberries.

When a strawberry flower is pollinated, the fruit doesn’t swell. The fertilized ovaries in the flower type separate, small, dry fruits. Those “seeds” ~ above the external of a strawberry room actually the fruits, every of which contains a solitary seed.

The ripe, red, fleshy part that us think of together the strawberry “fruit” is actually swollen receptacle tissue – the part of the tree that linked the flower to the stem. Once a strawberry flower is pollinated, it triggers the receptacle tissue to grow and change.

But the still doesn’t answer the question, the just changes it a little. Why are the small, dry fruits located on the outside of the red, sweet point that us all choose to eat?

The quick answer is that we don’t really know which evolutionary pressures caused the strawberry to develop the method that it did.

However, Gunter notes, “there are a couple of fundamental factors why plants have actually evolved various kinds of fruits. One factor is to lure something the spreads seeds.”

A an excellent example is the avocado. Scientists believe the avocado, v its enormous wood-like seed, progressed to be consumed by enormous pets that lived hundreds of years ago. One of these animals would chow under on part avocados and also either leave partially-eaten fruit (and the seed) nearby, or the seed would pass all the method through the animal and also be left behind in that waste. Since those huge beasts space no longer with us, avocados are currently dependent on person intervention to spread out their seeds.

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“A second evolutionary method is because that plants to discover ways for your fruit come disperse on your own,” Gunter says. “For example, they might fly in the wind, prefer a dandelion, or be relocated by the water, prefer a coconut.”

The 3rd option is because that a tree to discover ways for a fruit to deter animals from eating it. “For example, the gingko fruit smells putrid,” Gunter says. “The score there is for the fruit to not get eaten, so the the seed deserve to rely ~ above the fruit’s nutrient to assistance its growth.”

Presumably, the strawberry went because that evolutionary alternative number one – attract something to spread the seeds. Yet we don’t recognize the specifics.

*Note: The example for a true fruit was initially an apple. And then who told me that apples space not true fruit either. In fact, they belong to a group dubbed pseudo-carps, or false fruits. That’s since the part we think of as the fruit is made from plant parts other than the ovary. And – surprised – the fleshy component of an apple is also made of the receptacle tissue. In other words, it to be just around the worst example I can have thought of to hold up together the alternate to a strawberry. Yet now I recognize that – and so perform you!