response: Well, in Europe it was very common up until Middle Ages' end.  In fact, of the green vegetables, it was the most common!
original_response: Ha! Until the end of the Middle Ages, kale was one of the most common green vegetables!
history: Kale is so good for you. I try to eat it every day. Nice!  I know that kale leaves don't make a head, like headed cabbages do.  Also, their leaves can be purple or green! Oh cool.  Do you know anything about the history of kale?
knowledge: Until the end of the Middle Ages, kale was one of the most common green vegetables in Europe.