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.
Cultivation
The most important growing areas lie in central and northern Europe and North America. Kale grows more rarely in tropical areas as it prefers cooler climates. Kale is the most robust cabbage type - indeed the hardiness of kale is unmatched by any other vegetable. Kale will also tolerate nearly all soils provided that drainage is satisfactory. Another advantage is that kale rarely suffers from pests and diseases of other members of the cabbage family - pigeons, club root and cabbage root fly (Delia radicum).
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Origins
Until the end of the Middle Ages, kale was the common green vegetable in all of Europe. Curly leaved varieties of cabbage already existed along with flat leafed varieties in Greece, in the fourth century BC. These forms, which were referred to by the Romans as Sabellian kale, are considered to be the ancestors of modern kales. Today, one may differentiate between varieties according to the low, intermediate or high length of the stem, with varying leaf types. The leaf colours range from light green through green, dark green and violet-green to violet-brown. Russian kale was introduced into Canada (and then into the U.S.) by Russian traders in the 19th century.
Kai-lan, a separate cultivar of Brassica oleracea much used in Chinese cuisine, is somewhat similar to kale in appearance and is occasionally called "kale" in English.
Cultivars
Kale can be classified by leaf type:
* Curly leaved (Scots kales)
* Plain leaved
* Rape kale
* Leaf and spear (a cross between curly leaved and plain leaved kale)
* Cavolo nero (also known as black cabbage, Tuscan kale, Lacinato and dinosaur kale)
Because kale can grow well into winter, one variety of Rape kale is called 'Hungry Gap', named after the period in winter in traditional agriculture when little could be harvested.
Culinary uses
Kale freezes well and actually tastes sweeter and tastier after being exposed to a frost.
Tender kale greens can provide an intense addition to salads, particularly when combined with other such strongly-flavored ingredients such as dry-roasted peanuts, tamari-roasted almonds, or red pepper flakes.
A traditional Portuguese soup, caldo verde, combines pureed potatoes, diced kale, olive oil, broth, and generally sliced cooked spicy sausage. Under the name of couve, kale is also popular in the former Portuguese colony of Brazil, in caldo verde or as a vegetable dish, often cooked with carne seca (shredded dried beef).
A whole culture around kale has developed in north-western Germany around the towns of Bremen and Oldenburg. There, most social clubs of any kind will have a "Grünkohlfahrt" ("kale tour") sometime in January, visiting a country inn to consume large quantities of kale, sausage and schnapps. Most communities in the area have a yearly kale festival which includes naming a "kale king".
Curly kale is used in Halland, Sweden, to make långkål, an obligatory on the julbord in the region, and is commonly served together with the christmas ham.
Kale is very good source of iron, calcium, vitamin C, Folic Acid, vitamin K and Carotenoids (which provide vitamin A. Due to its high nutritional value it is often recommended as a way to consume many good nutrients.
Decorative uses
A variety called flowering kale is grown mainly for its ornamental leaves, which are brilliant white or violet on the interior. Most plants sold as "ornamental cabbage" are in fact kales.