Kale (Brassica oleracea) or leaf cabbage is a group of vegetable cultivars.
Until the end of the Middle Ages, kale was one of the most common green vegetables in Europe. Curly-leaved varieties of cabbage already existed along with flat-leaved 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. Russian kale was introduced into Canada (and then into the U.S.) by Russian traders in the 19th century. https://en.wikipedia.org/wiki/Kale