Mistletoe as a Christmas Evergreen

Can any of your readers inform me at what period of time the mistletoe came to be recognised as a Christmas evergreen? I am aware it played a great part in those ceremonies of the ancient Druids which took place towards the end of the year, but I cannot find any allusion to it, in connexion with the Christian festival, before the time of Herrick. You are of course aware, that there are still in existence some five or six very curious old carols, of as early, or even an earlier date than the fifteenth century, in praise of the holly or the ivy, which said carols used to be sung during the Chris…