I searched for variants on the Cruel Sister motif and found a ton of postings, but none that I saw mentioned this: The chorus of this song is frequently posted as "Lay the bent to the bonnie broom" or similar, with a lot of speculation on what "bent" means. I have no clue, but I know that a version sung by Old Blind Dogs as the line (as stated in the liner notes) as "Lay the bairn tae the bonnie broom." Not sure what that means, but as the note said, it gives a decidedly Scottish flavor to their version.

(Okay, I admit that I'm biased, but I think their version is the best I've heard yet!)

Cheers.