Is Onion a root, stem,or a fruit?- kitchen garden Facts

Is Onion a root, stem, or a fruit?- Onion is neither a root nor a stem. It is a tunicate bulb having a cluster of fleshy leaves. Technically what we eat in an Onion are the fleshy leaves. Also, it is not a fruit, obviously, it doesn’t develop from a flower.

Is onion a Root?- No, Onion has a fibrous root system but it is not entirely a root. The entire root system develops from the basal portion of an Onion bulb. Rest is the stem and leaves.

Is onion a Stem?- Technically Yes. An onion is a modified underground stem structure. The modification has made Onion as a unique tunicated bulb. The actual stem gets reduced to the flat base of the bulb. The rest of the fleshy portion is the concentric leaf structure attached to the stem.

The onion plant stores its processed food in the bulged leaf structure at the base. This bulged structure is the onion.

Is Onion a root, stem,or a fruit
Is Onion a root, stem,or a fruit?

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What makes an Onion different from Stem?

The discussion of Onion being root or stem is a generation old question. The opinions always differ but the fact is a fact. Some people say it a stem and others say a root. The answer comes from the point of consideration. It makes difference, whether you are talking about the entire bulb or just the part you like to eat.

According to biology, an Onion is a Bulb. It has a modified underground stem and a fibrous root structure. Does it mean an onion is a stem or root?

No certainly not. Every plant has these characterizations but when we talk specifically about the part of onions we eat. Then precisely it a group of concentric fleshy leaves. The entire edible bulb portion of an onion is a group of leaves.

The main stem of onion is the only flat disc stem at the base of the bulb. It does not have any segments, nodes, or intermediate nodes. Most important it is hard and we don’t eat it. So an onion is not a stem at least to the part we eat.

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What is an Onion- a Root or stem or anything else?

Onion is a tunicated bulb. The bulb resembles a flat disc-like underground stem structure that supports the root system and develops the leaves.

This scientific classification states that an onion is a modified stem. It contains a flat stem with the roots. This stem has a central concentric leaf structure. This is exactly what we see and eat.

If you slice an onion vertically then you can see a defined circular compact structure of fleshy leaves. New leaves originate at the center. The leaves grow big and get replaced by more new leaves. This continuous growth increases the size of the entire bulb.

The major portion of an onion bulb is comprised of leaves but these are not photosynthetic leaves. The onion plants need green leaves for photosynthesis like others. This is how we get our green sprout onions.

Onion is a perennial plant but commercially it is grown as annuals. It is harvested before attaining its maturity. We do so because when onion plants get mature it grows along a central stem tube and starts blooming. At this time the starch store in the bulb is used to feed the flowers and seeds it produces.  This means we have nothing left to eat now.

If you let an onion plant to get mature then you will get lots of onion seeds but not any bulb to eat.

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Is Onion a fruit?

No, never. Onion does have flowers and fruits i.e., seedpods but entirely it is the bulb we eat. There is nothing more explainable instead of saying that onion is developed with the roots, not the flowers.

So there is no chance of considering it a fruit.

More About a Simple Onion Bulb

Scientific Name Allium Cepa
Family Amaryllidaceae
Parts of Onion
  •      The top is the remains of previous green growth. (Tunic Leaves)
  •      Papery brown Scale Leaves
  •      Fleshy Leaves. Most of the edible part.
  •     Central lateral buds (Apical & Auxiliary buds)
  •     Modified stem or bulb. Mostly hard & inedible.
  •    Fibrous root System (Adventitious Roots)
Average Size 2cm to 8cm or 1-3.5 inch in diameter
Root Specialty  The Contractile or Pulling Root System. The roots of onion can contract to adjust the positioning of the bulb.

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Final Words

I know this debate does not end yet, still, I would like to conclude it in a more balanced way. Those who think an onion as a modified stem or fleshy bulgy basal leaves are both correct. If you think it is a root then think again. After all, it is what you can actually do. Overall this entire discussion is my own point of view. I would love to hear what you think about- Is Onion a root, stem, or a fruit?

Write down your views comments or suggestions in the comment box. I’ll be back with something more interesting than this. Till then keep reading keep gardening.


Hi, My name is Sukant. I am an I.T professional. Gardening for me is not just a hobby, it's a way of living life with nature. My Ancestors were Commercial farmers: So I personally feel attached to the green. I am not an expert, I'm here only to share my gardening experiences. It's always Refreshing.

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