Are you talking about the stem? Take your background 4 1/2" square and cut on the diagonal. Then center the long diagonal side of one of these triangles to a long side of the stem 1 3/4" x 7" and sew the seam. Do the same thing with the opposite side of the stem and the other triangle you cut on the diagonal. Press seams toward the stem. Then You need to square up this new square to be 4 1/2".
Does that make sense?
EDIT: I jumped ahead of you, this is later...