Get to know your brassicas!

In this era of rapid agricultural cultivation, hybridization, and even direct genetic engineering, a common refrain that often bubbles up is "Why can't we just leave vegetables the way God intended?"

The humour in such a statement, regardless of your individual religious beliefs, is that almost nothing we eat, whether flora or fauna, bears much resemblance at all to the natural organisms humans discovered when they arrived on the scene. See above for a beautiful photo of romanesco, a picture of the very miracle of life if there ever was one. God didn't do that. Evolution didn't do that either. People did.

To see what existed before humans got involved, behold the wild cabbage plant, the original Brassica oleracea:

We're lucky that it's one of relatively few pre-human agricultural plants that has survived in its original form into the modern era. A lot of original breeds of plants and animals have been lost to history. Wild brassica is still around thanks largely in part to its ability to survive in the barren highlands of northern England and Scotland where not much else grows. It's technically edible, but its hardy leaves are thick and tough, and recipes are best left to survivalists and forager hobbyists.

As early as the Greek and Roman times, people were selectively breeding Brassica oleracea into literally dozens of forms, many of which we know and love today: cabbage, broccoli, cauliflower, brussels sprouts, kale, collard greens. Yes, they're literally still all the same plant species and relatively cross-breedable.

Because for millennia, enterprising gardeners said, "Oh look, Antonio, this one does have the nicest leaves! Let's see if we can propagate more ones like this!" And the same goes for flowers, apical buds, lateral buds, roots, and so on.

Brassica oleracea variants spread across Asia too, and include beloved east Asian vegetables like Gai Lan.

You may have heard a lot of this before, as infographic memes about Brassica oleracea have become relatively common these days. Or maybe you hadn't and you're still taking in the awe of it all. But these infographics are leaving out half the story!

There's another wild Brassica, Brassica rapa, a type of wild mustard, that more or less got the same treatment.

Like its cabbagey cousin, Brassica rapa continues to thrive in the wild, often finding itself listed in various nuisance weed reference books. An edible weed, but still a nuisance. But what do you get when you add in a couple of millennia of human meddling? Another rainbow of instantly recognizeable supermarket veggies: bok choy, napa cabbage, Chinese cabbage, yu choy / choy sum, and even the lowly turnip root are all cultivars of the Brassica rapa species, painstakingly bred and selected for thousands of years.

"Well, okay, yeah, that's pretty cool, too," you may be thinking, "but what does this have to do with Brassica oleracea other than being a similar story of amazing gardening?" Well kids, when a cabbage loves a mustard very very much, sometimes they decide to have a baby. It turns out that Brassica oleracea and Brassica rapa are so closely related, that sometimes hybrids occur. And that's precisely what happened to create that Scottish favourite root, the rutabaga.

It seems somewhere along the line, and nobody's quite sure how, a turnip and a cabbage crossed to form a whole third species, Brassica napus. Swiss botanist Gaspard Bauhin first documented the rutabaga in 1612 in Sweden (hence one of its common names: swede), and Scottish folks have been eating their neeps and tatties ever since.

This might be the end of the story except for one interesting Canadian epilogue. The rutabaga is now known not to be the oldest Brassica napus. People had been expressing the seeds of various brassicas for cooking oils for some time. In fact the name of the Chinese green Yu Choy / You Cai 油菜 literally means "oil vegetable." And one plant processed in India for over 4000 years for cooking oil turns out to be a Brassica napus, just like the rutabaga. In English it has the unfortunate moniker of "rapeseed oil", after the Brassica rapa variant ("rapa" in Latin merely means root or turnip, nothing more salacious than that). You still sometimes see it sold that way.

At any rate, during World War II, an interesting thing happened. Supplies were scarce, and the Canadian war effort was desperate to find alternatives to petroleum for lubricating machinery, weapons, and vehicles. Rapeseed oil has the very useful characteristics of being extremely heat resistent (high smoke point) and also a relatively low viscosity compared to many plant based oils like peanut and olive and almost all animal based oils. Both are important if you're planning on greasing a tank with it (and also for high temperature cooking, a good topic for a future post). So Canadian scientists got to work analyzing the oil of various Brassicas and selecting a favourite.

Their initial choice for what ended up being known as Canola (Canada + Oil) was Brassica napus. The rutabaga plant. The little turnip that could.

The canola oil you buy in the store today for cooking (and please don't lubricate your engine with it) is from yet another wild mustard species, Brassica juncea, because selective breeding of that plant produces the best cooking oil results. That species also has some edible cultivars (some delicate mustard leaves mostly known in east Asia, like Japanese mizuna). But over the years Canola Oil has been made of all three of napus, rapa, and eventually juncea seeds as well.

A fascinating family history, is it not?

So next time your kid complains about "Boring old broccoli AGAIN?!?" you can tell them there's absolutely nothing boring about it.

[Disclaimer: Even with modern advances in DNA technology, discrete classification of various cultivars into one species or the other can be tricky, and some have been moved back and forth over time. Also, like canola, some have virtually identical versions in both family trees. Don't be surprised if you see different versions of this.]

Sources

• Canola Council. History of Canola Seed Development.

• Wikipedia. Rutabaga.

• Wikipedia. Brassica oleracea.

• Wikipedia. Brassica juncea.

• McGee, Harold. On Food and Cooking. 1984-2004, revised.