Vigilant as ever, duty calls. There’s a slim chance you may see an article in French about the famed Tuscan cabbage known as cavolo nero. It is my sad responsibility to tell you that bits of it are mistaken. ((I’d tell the author, but she does not seem to have thought of the possibility.)) Most important, the photo is certainly not cavolo nero. If it were, it would hardly match her description. Cavolo nero is much more of a kale than a hearted cabbage, and if you were to look in the market for something resembling her picture (which looks to me like a very ordinary Savoy cabbage, or verza), you would not be getting the authentic black Tuscan kale.
Our picture, which is definitely the real thing, is from Geomangio at flickr; I can’t easily find one of the whole plant.