Brassica oleracea var. botrytis – brassica is latin for cabbage, and oleracea for vegetable- like; botrytis means grape-like in Greek.
This is a vegetable that does not exist in the wild because it derives from kale, which is of ancient cultivation. It was popular in ancient Rome but originated in Syria where it was supposedly grown for over a millennium beforehand. Also called cole-flower in Tudor times, when the heads were no larger than tennis balls.