Kale is a highly nutritious, fast-growing winter crop that produces leaves that can be large and flat or with tightly curled or fringed edges. This species is known scientifically as Brassica oleracea (Acephala Group) and commonly as Kale, Borecole and Collards. The leaves can be green or purple depending on the variety. Tronchuda is a loose-leaf kale cultivar with a good flavour. The name means without head which is why you don't get a head of Kale.