Spring greens are a cultivar of Brassica oleracea in the cultivar Acephala Group, similar to kale, in which the central leaves o not form a head or form only a very loose one. It is considered to be closer to wild cabbage than most other domesticated forms, and is grown primarily in northern Europe, where its tolerance of cold winters is valued for an early spring supply of edible leaves. The Cultivar Group Acephala also includes curly kale and collard greens, which are extremely similar genetically.