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The Anatomy Of An Onion - Best Parts Of An Onion

Parts Of An Onion – The Anatomy Of An Amazing Vegetable

Onions are a staple food in many kitchens and a common ingredient in many dishes across different cultures of the world. But do you know what the different parts of an onion are? If you are interested in knowing about these different parts, let’s get learning.


You have probably eaten so many onions in your life over the years without much thought about the different parts of this vegetable. This seemingly simple vegetable has different parts that serve different functions in the growth, functioning, and reproduction of an onion. Let’s learn about them, shall we?

A bit of background about the onion

The onion  (Allium cepa L) is a widely cultivated root vegetable belonging to the genus Allium. It has many botanical varieties and is closely related to other vegetables such as garlic, scallions, leeks, and chives. The onion is a perennial or biennial plant but is mostly treated as an annual. When it is planted, it grows as green leaves aboveground and a bulb in the soil that has roots at the bottom.

Onions have been cultivated and bred for over 7000 years, which is why they are very well established. They are grown across the world and are used for the preparation of savory dishes, can be pickled, and also be used for non-culinary purposes such as hair growth oil.

Modern varieties of onions grow to about 6 to 18 in height and produce onion leaves of different shades of green depending on the variety and soil conditions in which the plants are grown. The underground parts or bulbs of the onion also come in different colors such as white, yellow, and red. All these onions have a pungent smell that adds wonderful flavors and aromas to foods. Onions can be eaten raw or cooked. When raw, however, they have certain substances that can cause eye irritation.

The Different Parts of an Onion

The onion has different parts that we shall now discuss.


First, it has 2 different types of leaves, that is scaly leaves and fleshy leaves. These are differentiated according to their position, look and texture or feel.

  • Scaly leaves are the dry, scaly, outermost part of the onion. These started as fleshy leaves over time and changed to become the way they are. The function of the scaly leaves is mostly protection for the rest of the bulb. These leaves protect the inner, softer parts of the onion bulb against pests and friction, giving the bulb room to grow.
  • The fleshy leaves are the most consumed part of an onion. Their primary function is to store antioxidants and nutrients such as flavonoids, anthocyanins, propanethial S-oxide, dimethyl Sulphate, and some vitamins and minerals.

Both the fleshy and scaly leaves of the onion have no photosynthetic activity as they receive no sunlight because they grow underground. They do however possess a lot of nutritional benefits and serve important functions for the onion.

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The bud

Inside the leaves is a small central bud at the tip of the stem. The bud is composed of embryonic cells that divide and multiply. The function of these cells is to help the onion grow. This bud is also where the flowers shoot out from. The flowers will eventually produce onion seeds.

Axillary buds

Around the central bud are axillary buds which are also important in the growth of the onion. They are specifically responsible for lateral growth as opposed to the central bud which is responsible for vertical growth.

The entire onion is often referred to as a modified stem. The condensed stem cells in an onion support the vital functions of the other parts of the onion and also transport nutrients to the bulb and roots of the plant.

All these parts described above make up the bulb of the onion, which is what we call “the onion”.

The roots

At the base of this bulb are short roots which extend a short way into the soil. These roots are called adventitious roots and are responsible for supporting the whole plant. They absorb all the nutrients and minerals from the soil, that the plants needs. Essentially, without these roots, the whole onion plant would not survive.

Green leaves

Aboveground are the leaves of the onion plant, different from the leaves of the bulb. These leaves are often green in color, fleshy, and fan-shaped. They alone can be used for culinary purposes and are actually regularly harvested and used even before the underground part of the onion, or the bulb is used.


This article taught you about the different parts of an onion as well as the different roles and functions these parts have. The next time you are chopping an onion to make your favorite dish or salad, take some time to appreciate this wonderful plant and all the complexities that go into making it the way it is, now that you know it is not as simple as a vegetable as it appears.

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why are parts of plants like an onion not green


Can I grow onions in my house?

Onions are hardy plants and easy to grow indoors. Green onions, or scallions, are popular with indoor and casual gardeners because of how easily they grow.

What is the difference between an onion and a shallot?

Shallots have a delicate and sweet flavor with a hint of sharpness, while onions bring a more intense heat.