Kale is a member of the species Brassica oleracea (Acephala group) which also contains a wide array of other vegetables – including broccoli, cauliflower, collard greens, and Brussels sprouts. Kale has green or purple leaves which do not form a central head. Most kales are either annuals or biennials, and are raised from seeds that resemble cabbage seeds. Kales are available as curly-leaved, plain-leaved, or a cross of both called “leaf and spear.”
Kale freezes well and tastes sweeter and more flavorful after being exposed to a frost. The tender greens of Kale can provide an intense addition to salads, particularly when combined with other such strongly flavored ingredients as dry-roasted peanuts or red pepper flakes. When combined with oils or lemon juice, Kale's flavor is noticeably milder. When baked or dehydrated, Kale takes on a consistency similar to that of a potato chip and can be seasoned with salt or other spices. Kale is very high in beta carotene, vitamin K, vitamin C, and rich in calcium.
There are several varieties of Kale grown during cooler weather explicitly for their ornamental leaves that are colored brilliant white, red, pink, lavender, blue or violet in the interior of the rosette. Ornamental Kale, however, happens to be as edible as any other type of kale.