seakale Crambe maritima, is a member of the cabbage family, Cruciferae, as its generic name suggests (krambe being Greek for cabbage), but it is not a type of kale. Nor is it a relative of seakale beet (a kind of chard).
Seakale grows wild around the shores of Europe from the Atlantic to the Black Sea. If it grows normally it is bitter and inedible. If, however, the wind covers a young plant with sand, it is cut off from the light and develops a thick, blanched leaf stalk with a tiny, under-developed leaf at the tip. The result is a tender, mild stem vegetable which can be eaten like asparagus, although it takes longer to cook.