What’s your favourite green vegetable? Kale? Broccoli? Cabbage – regular, red, or savoy? Brussels sprouts? Cauliflower? Trick question. They’re all the same species.
In these blog posts I try to find facts that are interesting but not well-known. The trick is assessing just what is well-known and what is not. This one came as a surprise to me when I first learned it. You, on the other hand, might think this one was obvious.
Brassica oleracea has been cultivated for thousands of years, and in the process it has split off into a number of different cultivars. If people ate the leaves and bred for bigger leaves, they got kale and then cabbage; if people grew them for big chunky flowers, they got cauliflower and then broccoli. As well as the list above, cultivars include collard greens, kohlrabi (German turnip), and gai lan (Chinese broccoli). Here’s the rough timeline:
The original – wild cabbage
5th century BCE – kale
1st century CE – cabbage and kohlrabi
15th century CE – cauliflower
16th century CE – broccoli
18th century CE – Brussels sprouts
The original cabbage, the wild cabbage, grows in the northern Mediterranean. It looks kind of scrappy and weedy – but that’s no surprise.
My favourite cultivar has to be the Jersey cabbage: it grows upwards like a tree, 3 metres tall. The woody trunk is strong enough to be carved into a walking stick. The fractal pattern of the Romanesco broccoli (see the centre of the picture above) is also pretty cool. I’ll write about the math behind that broccoli another time.
The Generalist Academy 
You might enjoy the “Triangle of U”.
I’d never heard of it, but you’re right, I do! Definitely will use that as a future post, thank you eub.