Ok here's how to work the stitch: First form a straight stitch by bringing the needle up at 1 and down at 2. Then bring the needle up again at 3 slightly to one side of the first straight stitch at an angle. Then take your needle back down at 2 and then up at 4 again slightly at an angle. Complete the stitch by taking the needle back down at 2, the stitch is now complete.
To work a row of fern stitch along a curve position the first three stitches at the tip of the line then bring the needle up slightly below at 1, then take the needle down again at 2. Bring the needle up again at 3 and then back down again at 1. Bring the needle up at 4 and down at 1 to finish the stitch. Work along the line in this way. The angle of the straight stitches can be altered in size and length to represent the foliage.