Cruciferous Vegetables

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Podcast Transcript

One of the most common food items consumed today are cruciferous vegetables. Even if you aren’t familiar with the term, you almost certainly have consumed some before, and there is a good chance you do so on a regular basis. 

What many people don’t know is that these vegetables are actually rather modern. 

Early neolithic humans never ate broccoli, cabbage, or Brussels sprouts because humans invented these foods. 

Learn more about cruciferous vegetables and where they came from on this episode of Everything Everywhere Daily.

If you are not familiar with the term cruciferous vegetable, you are almost certainly familiar with cruciferous vegetables themselves. 

Cruciferous vegetables are an entire category of vegetables that includes a wide variety of plants that seem, at first glance, to be very different. 

Without going through an exhaustive list, here are some cruciferous vegetables that you might be familiar with:

  • Kale
  • Collard Greens
  • Broccoli
  • Cauliflower
  • Cabbage
  • Red cabbage
  • Kohlrabi
  • Chinese Kale
  • Savoy cabbage

That list isn’t even close to being comprehensive, but it demonstrates the wide number of very common vegetables that are considered to be cruciferous vegetables.

Why are they called cruciferous vegetables?

It comes from the Latin word Cruciferae, which means cross-bearing, which is due to the four leaves the plants have and how they are arranged. Many of the vegetables I listed, like broccoli, are ones you might have consumed without ever having seen their leaves. 

All of these vegetables are plants in the family Brassicaceae. In addition to the vegetables I listed, it includes mustard plants and plants such as rapeseed, which is what canola oil is made out of.

But what this episode is really about is one particular species in the family, Brassica oleracea.

You probably haven’t heard of Brassica oleracea, and you probably haven’t eaten it, but without it, the foods we know today would be very different. 

Brassica oleracea can be found in the wild across southern and western Europe. It is a leafy plant that, if you saw it on the ground, you would probably think that it was a large weed.

It is a biennial plant that has a two-year growing cycle. In the first year, it stores nutrients and water in its large leaves, and in the second year, it creates a very tall flower spike that can grow as large as six feet or two meters.

The plant is relatively salt tolerant but doesn’t tolerate other plants growing in proximity.

Brassica oleracea typically only grows along cliffs made of limestone. The plant can be commonly found along the chalk cliffs in Dover, England. Likewise, many plants can be found along the coast of France. 

So, what does this cliff-dwelling European plant have to do with anything?

Every single vegetable that I previously listed is derived from Brassica oleracea. Or, to put it another way, none of the vegetables I listed are found in nature. 

There is no such thing as wild broccoli, cabbage, or cauliflower. It is possible you could come across a feral version of it, which somehow came from seed from a farm, but they never existed in the wild. 

If that is the case, then how and why do these plants exist? 

That story is what makes cruciferous vegetables so interesting. 

Humans began cultivating Brassica oleracea thousands of years ago. We aren’t sure exactly when or where it happened, but it began one of the most successful cases of human selective breeding of plants. 

Most people don’t realize that almost the crops we consume today are nothing like the wild varieties that were first cultivated. There were no big juicy apples and oranges out in the forest. There weren’t ears of corn the size you see today. 

The humans who cultivated Brassica oleracea simply collected the seeds from the plants they liked the best and kept planting them. Without even knowing it, they were engaging in selective breeding. 

The very first of these crops that was probably created was probably cabbage. 

Cabbage was first developed sometime around about 1000 BC, most probably by Celtic people who lived in Western Europe. However, there are theories that place the origin of cabbage along the Mediterranean. 

The ancient Greeks and Romans highly valued cabbage for its health benefits and versatility in cooking. The Romans, in particular, developed several varieties of cabbage and included it in their diet for both medicinal and culinary purposes.

The Romans really had a thing for cabbage. Pliny the Elder mentions a treatise on cabbages that was written by the Greek physician Chrysippus of Cnidos. However, that text has been lost to history. 

Pliny the Eldge also mentioned seven different cabbage varieties that were being grown in Rome at the time. 

Emperor Diocletian, after bringing stability to the empire, decided to retire to grow cabbages. When people begged him to return to power to restore leadership from Emperor Constantine, he reportedly said, “If you could show the cabbage that I planted with my own hands to your emperor, he definitely wouldn’t dare suggest that I replace the peace and happiness of this place with the storms of a never-satisfied greed.”

The cabbage grown and consumed by the Romans was probably something closer to kale than the modern version, with densely packed leaves in the shape of a sphere.

The first mention that makes a distinction between harder head cabbage and looser kale didn’t occur until the 13th century, and by the 14th century, records in England made a clear distinction between the two types of cabbage.

In the Middle Ages, cabbage was a food for both the rich and the poor. It was easy to grow, and in warmer climates, it could be grown almost year-round. 

Cabbage and kale might have been the first cruciferous vegetables to be cultivated, but they were hardly the only ones. 

As more cabbage and kale varieties were selectively bred, more vegetables were created as well.

Collard greens are a type of kale, and some form of them date back over 2000 years. 

Kohlrabi, whose name in German means cabbage turnip, was first documented as having come to Italy in 1536. 

Some early forms of broccoli and cauliflower certainly existed in ancient Rome, but we have no idea how close it was to the type we have today. We don’t know if cauliflower, for example, was independently created from other types of cabbage or if it came from broccoli. 

Cauliflower certainly does look like white broccoli, but that doesn’t necessarily mean that one was derived from the other.

The Romans knew a variety of cabbage they called cyma. Cyma found its way to the island of Cyprus, where it was then reintroduced in Italy around 1490. 

Broccoli most probably came from Roman varieties of cabbage, and it remained in Italy for centuries, where it underwent more selective breeding. It isn’t recorded as leaving Italy until the 18th century. 

If you remember, in one of my early episodes, the name Broccoli came from an Italian family that introduced the vegetable to the United States, and members of the  Broccoli family were responsible for producing the James Bond films. 

Brussels sprouts are derived from older forms of cabbage, and as their name would suggest, the variety we know, or something similar, was first created around the city of Brussels in the 13th century. 

It might seem odd that all of these vegetables are derived from the same plant, but it’s true. 

However, the story is actually even stranger. 

The list of vegetables I gave you is not complete. There are more cruciferous vegetables that are not directly descended from Brassica oleracea. 

Horseradish, radishes, turnips, Rutabaga, white mustard, black mustard, brown mustard, watercress, wasabi, arugula, and many others.

Most of these were selectively bred from two other species, Brassica rapa and Brassica nigra.

One of the reasons so many varieties of cruciferous vegetables were able to be created from just a small number of original plants is something called The Triangle of U. 

The “U” in the Triangle of U refers to Dr. U Jang-chun, a Korean botanist who studied plants in the family Brassicaceae in the early 20th century.

The Triangle of U is a concept used in plant genetics to understand the relationships and origins of crops within the Brassica genus. 

Imagine a triangle, where each corner of the triangle represents one of three ancestral wild species of the Brassica genus. Brassica rapa, Brassica nigra and Brassica oleracea. 

The sides of the triangle represent the hybrid species that are created when two of the ancestral species are crossed.

The triangle can explain how cross-breeding can occur and how new varietals can arise, in addition to the selective breeding of individual species. 

While these vegetables have been selectively bred for centuries, efforts in this area haven’t stopped. 

Centuries ago, the crops spread to Asia, Africa, and the Americas, and new varietals were created there, too. Bok choy, also known as Chinese cabbage, is descended from this original line. 

New cruciferous vegetables have been created recently, too. 

Broccolini is a cross between broccoli and Chinese kale, also known as gai lan.

Komatsuna is a leafy Japanese offshoot of Brassica rapa

In 1992, Dutch researchers identified the chemical in Brussels sprouts that made them biter and then selectively bred versions to remove the bitterness and taste better. 

Of course, as with almost all crops, varietals were created with attributes including increased production, cold weather and insect resistance, and better nutritional profiles. 

Not every green leafy vegetable is a cruciferous vegetable. Lettuce and spinach, for example, are not. 

Cruciferous vegetables differ from one another, but they are widely considered to be good sources of vitamin C and soluble fiber. 

Cruciferous Vegetables are a staple food in many people’s diets, and they are some of the most common crops that people grow in their own gardens. 

The Amazing thing is that the large number of diverse plants that all seem so different from each other are all actually the descendants of a few ancient plant species. 

They became so different because of the continued selective breeding efforts by humans over thousands of years who simply wanted to make better crops.