'Mulberries' in the Bible

and David asketh again of God, and God saith to him, 'Do not go up after them, turn round from them, and thou hast come to them from over-against the mulberries;

and it cometh to pass, when thou hearest the sound of the stepping at the heads of the mulberries, then thou goest out into battle, for God hath gone out before thee to smite the camp of the Philistines.'