What Fruit Has Seeds on the Outside?

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Strawberries have seeds on the outside.
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The strawberry is unique in the fruit world and not only because it looks and tastes so good. It is the only kind of fruit that has what appears to be seeds on the outside. However, botanical experts say that they are not actually seeds.

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Fruits With Seeds on the Outside

Every strawberry has more than 200 brownish "seeds" on its surface, but botanists know that these features are really something else. Strawberry plants produce flowers, which are then pollinated. The fertilized ovaries within the flowers then separate into small, dry fruits (achenes) that appear on the red surfaces. Each of these contains one separate seed. Another example of a plant with achenes is the sunflower.

Interestingly, the familiar and fleshy red part of the strawberry is a "swollen receptacle tissue" that connects the plant's flowers to its stems. Once the flowers are pollinated, the receptacle tissues change and begin to grow and expand into the familiar triangular shape. Experts disagree as to why the achenes are on the outside rather than inside the strawberries. Some believe that it makes them more attractive to the animals who consume them.

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The achenes then become waste products that enter the environment, helping the plants to reproduce and flourish. Another theory is that being on the outside makes the achenes easier to spread. They do not have to be eaten and excreted; they can get stuck on fur or feathers and get moved about in that fashion. Achenes can even stick onto clothing and shoes.

What Exactly Is Fruit?

Fruits are defined as mature, ripened ovaries of flowers. Once the flower is fertilized and pollinated, its ovaries mature and ripen. The flower's structural layers change, the petals drop off and the ovaries increase in size. Not all fruits are edible, not all are sweet and they come in many different shapes and forms. The main role of fruit is to spread the plant's seeds to help it reproduce.

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Are you wondering how the field of botany classifies types of fruits? First is aggregate fruit, like strawberries, which develop from one flower that has many pistils. Drupe fruit has one seed, fleshy fruit and a hard covering – think coconuts, peaches and olives. Pome fruits are formed under the flowers' receptacles, and two examples of these are apples and pears.

When several flowers join together, you see multiple fruits, such as the pineapple. Grains, such as rice and barley, are also similar since they have both fruit and seed joined together. Another classification is berry fruits, which does not include strawberries.

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Types of Berries

It's true: Botanists do not consider strawberries, blackberries and raspberries as true berries. Real berries are formed from an ovary of one flower, with small seeds embedded within the fleshy fruit. Examples of true berries include:

  • Blueberries
  • Cranberries
  • Grapes
  • Gooseberries
  • Bananas
  • Peppers
  • Tomatoes

The big three (strawberries, blackberries and raspberries) are in the aggregate fruit category (one flower, many pistils). All three have achenes. Interestingly, quinoa, buckwheat, buttercup, caraway and cannabis are all examples of achenes. Another interesting botany fact is that although we call cucumbers, tomatoes and peppers vegetables, all are technically fruit, and so are maple keys, acorns and the outside of sunflower seeds.

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