The question of is an onion a vegetable or a fruit is an interesting one. But it isn’t difficult to answer. Onions fit both the scientific definition and the commonly used definition of a vegetable. They can be served and eaten in a wide variety of ways. While some prefer a thick slice to top a burger, others prefer the delicate flavor attained from sautéing them.
Is an onion a fruit or vegetable?
An onion is the edible underground bulb of the onion plant, making it a vegetable. Onions do not contain the seeds of the onion plant and are not fruit. Onions are typically served with poultry, fish, or meats, so they fit the common definition of vegetables, too.
What is the definition of a vegetable?
The technical definition of a vegetable is any plant part that is used for food. This includes leaves, stems, roots, tubers, bulbs, and flowers. But the common definition of vegetables reflects how it is typically served. Many people refer to vegetables as those plant parts that are generally prepared or served with meats, poultry, or fish.
This can lead to some confusion over which plant parts are vegetables and which are fruits. For example, tomatoes, cucumbers, and squash are technically fruits but are often referred to as vegetables because of how they are served.
What is the definition of a fruit?
A fruit is the mature ovary of a plant and contains seeds. Fruits develop from blossoms on the plant and are the plant’s way of reproducing. Many think that all fruits are sweet and used for desserts or making jams and jellies, but this isn’t always the case.
Tomatoes, peppers, eggplants, and squashes are actually fruits as they form when the blossoms are pollinated and contain the plant’s seeds. These fruits are typically referred to as vegetables because they are served with poultry, meats, or fish.
Is an onion a vegetable?
Onions are the edible bulb of the onion plant, making them a vegetable. They can be served raw, sautéed, deep-fried (onion rings or onion blossoms), boiled, roasted, or even cooked up on the grill. They are used to flavor soups, sauces, and stews.
This versatile vegetable is a staple in many households because it can be used in a wide variety of dishes to enhance the flavor of meats and poultry. Onions are prized for their intense flavor.
Why do people think onions are fruits?
Some people may think that onions are fruits because they are round and resemble the body of many fruits. But onions are actually the onion plant’s underground bulbs, making them a vegetable.
Where do seeds form on onion plants?
Onion plants produce a stalk with blossoms that make the seeds of the onion plant, but the onions you grow in your garden may not produce flowers and seeds. Onions are actually a perennial that will return each year if left in the ground. They typically do not bloom or form seeds in the first year.

Onions grown in the garden are generally harvested and eaten in their first year, but they will likely produce blooms in the second year and form seeds if they are left in the soil. Onions seeds form after the blooms are pollinated, and the flower petals drop from the plant. Onions blossoms look similar to chive blossoms and may be white, purple, or shades of lavender and pink, depending on the variety of onions.
Why do onions make you cry?
When you cut into an onion, it releases the chemical lachrymatory factor that contains sulfur. The enzyme alliinase (also present in onions) starts a chemical reaction that converts the sulfoxides in the lachrymatory factor to a vapor that irritates the eyes. This, in turn, causes your eyes to burn or tear and produces the customary “crying’ associated with slicing or dicing onions.
It is believed the onion’s ability to release eye-irritating vapors is a defense mechanism of the onion to prevent it from being eaten by animals in the wild and therefore ensure the onion plant will mature and reproduce.
Why are onions sweet when you sauté them?
Sautéing onions causes a chemical reaction in the onions as they lose moisture and heat up. The natural starches and sugars in the onion begin to break down, giving them the sweet flavor associated with sautéed or caramelized onions. Sautéed onions don’t actually contain more sugar than raw onions. The sugar is broken down into smaller molecules that our taste buds can detect.
Onions must be heated to 212 degrees to fully break down the starches and sugars in the onion’s flesh. This also causes the color of the onion to change and eventually turn golden brown.
Are there different kinds of onions?
Onions can be white, yellow, or red (purple). Some onions, like Vidalia and Walla Walla onions, are mild and sweet, while others, like white onions, are sharp and pungent. Yellow onions are typically considered an all-purpose onion as they are less pungent than white onions and not as sweet as sweet onions are.
Red onions have a similar flavor to yellow onions and are typically eaten raw in salads or salsas, where their color enhances the meal’s presentation. It should be noted that red onions lose much of their color when cooked.
How do you prevent onions from being too strong?
If you prefer the flavor of milder onions in your salads or in sandwiches but are working with strong onions, there is an easy solution. To eliminate some of the bite from pungent onions, you can soak the sliced or diced onions in water for at least 10 minutes.
Place the sliced onions in a bowl of ice water and set them on the counter for at least 10 minutes before adding them to sandwiches or salads. Stir them after 5 minutes to help wash away the sulfur compounds on the onion slices. Drain the onion slices and serve.
Summary
Onions are definitely vegetables, regardless of if you prefer the scientific or common definition of vegetables. They are used to enhance the flavor of soups and stews and used in tomato dishes to bring out the tomatoey flavor in Italian dishes. Onions are also served raw in sandwiches, salads, and salsas.
Links:
Red, Yellow and White Onions Sets (40 Blubs) for planting
Further Reading:
https://www.sciencenewsforstudents.org/article/why-onions-make-us-cry