Wikipedia Article About Kale on Wikipedia
Kale is a form of cabbage (Brassica oleracea Acephala Group) in which the central leaves do not form a head. It is considered to be closer to wild cabbage than most domesticated forms. The species Brassica oleracea contains a wide array of vegetables, including broccoli, cauliflower, and Brussels sprouts. The Cultivar Group Acephala also includes spring greens and collard greens, which are extremely similar genetically.