People are inclined to think that spring greens are just cabbages harvested early, but they are in fact a cultivar of Brassica oleracea in the Acephala group, meaning that they do not form a heart as cabbages often do. Although this is thought to be closely related to the wild cabbage it is welcomed in northern Europe when it appears in spring for its sweetness. I really enjoy the first spring greens and cook them lightly with a little juniper and garlic.
Spring greens can also describe the loose outer leaves of other brassicas, which might be cooked separately and given this name. Spring greens are described as strong-flavoured sometimes, but I think this generally refers to these discarded outer leaves rather than true spring greens, freshly harvested.
