I was just chopping up a head of cabbage for coleslaw, after peeling off some of the outer leaves. I started thinking about how we ended up with such a tightly packed mass of leaves. Aren’t leaves mostly for photosynthesis? How can they do their job when they’re all mashed in like that? Or are we eating immature leaves, and the head would open up more later?
Yes, I do realize that we’ve got umpty-ump centuries of human breeding here, but the starting place was still a bunched group of leaves, right?
I think kale is probably closest to the wild form. Kale, cabbage, Brussels sprouts, broccoli, and cauliflower are all the same species, just selectively bred for different features. Given the structures found in those plants, I suspect that the leaf-bunching originated as a way of protecting the flowers.
Cabbages have been intensively bread to improve their usefulness - to and by humans - for ages. The cabbage doesn’t care that it can’t photosynthesize (if that’s even true) as well as it’s cousins, as long as it can procreate, and humans can easily ensure that.
Yeah, I know, which is why I included my acknowledgment that it’s a matter of breeding now in the OP. I wasn’t clear about the ancestral cabbage.
A friend has told me via PM that we are, indeed, eating immature leaves, and that the cabbage very slowly opens, with outer leaves dying off as new ones separate from the head. The roots feed the plant until the leaves are ready to do their photosynthesis thing.
From what I recall, no one is quite sure what the ancestral plant was. Some think it was a plant that grows off the cost of England called sea cabbage (or maybe sea kale). At any rate, all the plants cabbage, kale, brussels sprouts, broccoli, cauliflower, kohlrabi, and collard greens are all the same species, Brassica oleracea. Turnip and mustard are closely related species.
The point is that all parts of the brassica are edible, roots, leaves, flowers, stems and the various varieties were created by emphasizing different parts of the plant. They are all genetically modified but by a hit and miss process rather than by design.
Some book on vegetable gardening reported that the Romans ate the stalk of the cabbage, not the leaves. I’ve never bothered to attempt to check this but this would seem resonable in view of Colibri’s link.
Emplasis added. From the Medieval book, Tacuinum Sanitatis, you can see that this is true. The TS was late 14th century. So unless they were simply copying from older manuscripts and ignoring what was growing in their gardens, head-forming is a late addition to the cabbage.
Just thought I’d post link to a quick Google search that ought to answer the question pretty well: Cabbage plant picture
The outer unfolded leaves are quite clear in most of these pictures. Farmers only harvest the internal head, but that head is really a small part of the total plant. But the pictures also show that the head is either missing altogether or quite small in certain varieties/ages of cabbages.
