304 North Cardinal St.
Dorchester Center, MA 02124
The simple onion is ubiquitous!
There’s practically no school of cuisine in the world that doesn’t utilize healthy onions in their regionally tasty recipes. Many chefs cultivate their own onion bulbs in kitchen gardens.
But are these bulb vegetables or bulb fruit?
And how do we make this distinction for a plant species?
We asked some botanists and top chefs and this is what they told us.
While there are botanical definitions of these things, in the United States, the United States Department of Agriculture (USDA) defines these things and they make no reference to the science of botany in their definition.
They have a definition of every fruit permitted to be sold in the United States and what standards it must meet to gain a particular grading.
They also have 5 categories of vegetables and the 5th is “anything the USDA deems a vegetable that doesn’t fit in the other four categories”.
Onion plants have been deemed a vegetable.
These flowering plants are only considered useful for the root which produces sweet onions, yellow onions, red onions, etc. and thus, they are not seen as a flowering plant by the USDA but rather that special type of vegetable in the 5th category because that’s what the USDA says it is.
While the USDA may be arbitrary about these things, we would note that botanists are less so.
They say that because onion seeds develop into a plant where the onion is separate from the seeds inside – it is clear that the onion is a vegetable.
A fruit always contains seeds as it is, essentially, a plant’s ovaries.
Bulbous plants like onions can perform a special trick. You can plant the bulb and grow new onions.
This means that some people insist that an onion must be a fruit. But they’re wrong.
The bulb is not an onion seed, even if you get a similar result from planting a bulb as you would with a seed.
There are no seeds in the bulb at all and thus, it’s very much a vegetable.
We mentioned that bulb onions have flowers, right?
Well, seeds don’t come from the stem and scale leaves or the bulb they come from the flowers.
Onions grown from seeds must have the seeds fertilized prior to planting. We would also note that if you want your onions to be able to last through many generations it’s best to let some onion flowers grow and get those seeds every now and again.
This allows for genetic diversity in the onions that you grow and ensures that when you get more onions, they are healthy.
One really peculiar aspect of the arbitrary nature of vegetable classification is that in the US, sometimes it’s a court that decides whether or not something is a vegetable.
While we categorize onions correctly, an American court decided that tomatoes were a vegetable (not a fruit) simply because most people call a tomato a vegetable! This is also true of cucumbers, believe it or not.
Onions aren’t even a true root vegetable, though they are a vegetable.
Botanists distinguish true roots as those with tuberous roots like a potato or a carrot.
Not that we care, onions are tasty whether eaten raw, as pickled onions, or in pretty much any dish that we can think of. They’re one of our favorite vegetables, in fact.
Want some tasty recipes for your onions?