Entry # 3 and #4 are both good, as the single letter N is an Icon worth exploring. Please release them back into the competition. I work with Steve above, so he won't mind me suggesting this.
Further, all your designs, where the Fern sits to one side of the Letter N, can you have the letter in say and brilliant turqois blue, smoothly transitioning to a wonderful Fern Green color for the fern. Such that the whole letter N including the fern, is of 2 colors?
R