Home gardening in winter is depressing. There is little in the way of instant seasonal gratification: vegetables in Melbourne grow at a slow and infuriating pace. The last of summer’s harvest that has been ferreted away at the bottom of the freezer runs out. I stare out at the thin tendrils of leek that poke through the mulch and deeply believe that they’re shrinking due to a seasonal disorder.
Looking at SBS’s guide to what is in season, the big winners in winter are cabbage and the rest of the brassica olearacea cultivars: broccoli, kale, brussel sprouts, kohlrabi and cauliflower. What is amazing about them, apart from their love of winter, is that they’re all cultivars of the same plant most of whom were only developed over the last 500 years through the slow process of selection.
In the wild, brassica olearacea is a leafy weed that is indigenous to coastal southern and western Europe. It endures salt and is a poor competitor with other weeds, limiting it to rocky limestone cliffs. It only looks cabbage-like in a very loose sense. It looks strongly like a coastal weed. In all likelihood, it was probably one of the earlier plants in the Mediterranean to have been domesticated in the region. It is not too hard to see that Kale was derived from this coastal weed, through the process of generations of farmers selecting to grow the plants with the largest (or tastiest) leaves.
As with practically every Mediterranean food, its spread around Europe has been ascribed to the Romans because they were the first people to document such things. The Celts probably had an earlier role in the dissemination of brassica around the world because the Latin name brassica seems to be derived from the Celtic word for cabbage, bresic.
The transition of brassica olearacea from a loose bundle of leaves to a tight head of cabbage is described by Brian Baldwin from the University of Saskatchewan as follows:
As time passed, however, some people began to express a preference for those plants with a tight cluster of tender young leaves in the centre of the plant at the top of the stem. Because of this preference for plants in which there were a large number of tender leaves closely packed into the terminal bud at the top of the stem, these plants were selected and propagated more frequently. A continued favouritism of these plants for hundreds of successive generations resulted in the gradual formation of a more and more dense cluster of leaves at the top of the plant. Eventually, the cluster of leaves became so large, it tended to dominate the whole plant, and the cabbage "head" we know today was born. This progression is thought to have been complete in the 1st century A.D. This plant was named Brassica oleracea variety capitata, which translates to "cabbage of the vegetable garden with a head."
At about the same time, in a part of Europe near modern Germany, kale plants with short fleshy stems were being selected, resulting in fatter and fatter stems. Selection on this basis eventually led to the ancestral "cabbage" plant developing into the vegetable we know as kohlrabi. The kohlrabi plant was named by botanists as Brassica oleracea variety caulorapa, with the last word meaning, "stem turnip." Both cabbage and kohlrabi have been cultivated for about two thousand years.
Similarly, a preference for eating the immature flower buds of brassica favoured the growth of ever larger flowering heads in the plant. By the 1600s, this had been developed into cauliflower and by 1700, broccoli. The last of brassicas to be developed was brussel sprouts, which while referred to in texts from the 1580s, were not cultivated widely around Europe and in the Americas until the 1800s.
As for what to do with the season's cabbages, SBS maintains a solid list of cabbage recipes.