Kale (/keɪl/), or leaf cabbage, belongs to a group of cabbage (Brassica oleracea) cultivars grown for their edible leaves, although some are used as ornamentals. Kale plants have green or purple leaves, and the central leaves do not form a head (as with headed cabbage). Kales are considered to be closer to wild cabbage than most of the many domesticated forms of Brassica oleracea. Kale is usually an annual plant grown from seed with a wide range of germination temperatures. It is hardy and thrives in wintertime, and can survive in temperatures as low as –15.0° Celsius. Kale can become sweeter in taste after a heavy frost. (Source: Wikipedia.org, CC BY-SA)