Kale is a different species from Chinese kale and from collards, but the plants have several features in common. All have rather coarse and strongly flavoured leaves, and the stems are usually thick requiring more cooking time. Kale and cabbage are varieties of the same species and descended from the same wild ancestor, but kale is the more primitive of the two, like cabbage without a head.
Kale should be wrapped in a damp paper towel, placed in a plastic bag and stored in the refrigerator crisper. It should not be washed before storing since this may cause it to become limp. Kale can be kept in the refrigerator for several days, although it is best when eaten within one or two days after you receive it, since the longer it is stored, the more bitter its flavor becomes.
The Kailyard school of Scottish writers, which included J. M. Barrie (author of Peter Pan), consisted of authors who wrote about traditional rural Scottish life (kailyard = kale field) in the nineteenth century. Prior to that, such is the humble, but ubiquitous, origin of kale in human history that this hearty plant, referred to by one name or another, turns up in the recorded history of nearly every country of Europe and Asia.
As it turns out, our modern word 'kale' is a Scottish word derived from "coles" or 'caulis,' terms used by the Greeks and Romans in referring to the whole cabbage-like group of plants. For this family group the English language has no generic name. The French include them all under the term Chou and the Germans under Kohl.
Like broccoli, cauliflower and collards, kale is a descendent of the wild cabbage, a plant thought to have originated in Asia Minor and to have been brought to Europe around 600 B.C. by groups of Celtic wanderers. Curly kale played an important role in early European food culture, having been a significant crop during ancient Roman times and a popular vegetable eaten by peasants in the Middle Ages. Kale was brought to North America by English settlers in the 17th century.
One cup of kale contains 5 grams of fibre, 134 milligrams of calcium, and the full daily recommended allowance of vitamins A and C. Kale also contains beta-carotene, lateen, chlorophyll, indoles, sulforaphane and other powerful cancer fighters. Nutrients in kale are said to boost the immune system, reduce the risk of heart disease, and some research suggests that kale may help delay the onset of aging.
Unlike other greens that reduce in size up to eight times during cooking, kale only shrinks by half or a quarter. The older the leaf, the longer it will require cooking. Kale can be chopped and used raw in salads, cooked and added to rice or barley dishes, or served on its own as a side dish. The stalk and the leaf should be separated as each varies in its cooking times, with the stalks taking much longer than the leaf.