What is the meaning of the black ribbon?

well.. couldn't contain myself..

started researching young girls head attire in 16th century Germanic..

well..
mostly they have their hair let out and nothing on their heads or braided.. or a flower wreath.. perhaps a simple hat.. or the alluring little black ribbon..

Does it have a purpose? Is it a fashion statement?

Portrait of a young girl (presumably Magdalena Luther) by Lucas Cranach the Elder
Probably before 1537, possibly 1528/29

At the moment I've just started researching and I've made a pinterest board (well ofcourse I did..)

You can find it here: http://www.pinterest.com/aelfwynne/garb-ideas-germanic-15-16th-c-girlsyoung-women/

Know what's up?

Please let me know :)