The combination of the buttonhole stitch and the stem stitch around a motif, in this case with three different colors, allows the motif to raise up a bit and provides more texture and a 3-D effect. One of the things I do the most is to use several rows of stem stitch. I love the way it feels and the shading possibilities. I consider it my signature style.
The Stem Stitch
I use the stem stitch to outline motifs and to make vines and lines. The stem stitch is sometimes confused with the Outline Stitch. The difference is that the Stem stitch needle comes out of the fabric above the thread and the Outline stitch needle comes out of the fabric below the thread. The stem stitch looks ropey with the threads being visible in each stitch. The outline stitch is much smoother with the visible distinction between stitch threads less discernible and less ropey. Both stitches have their good uses. I prefer the Stem Stitch because I generally like the ropey textured effect better.
Stitching over a drawn line. Note that you can see that I tend to give my leaves and branches a bit of a point effect using the stem stitch and a straight stitch to fill in the point.
Stitching around an applique motif the first time
Stitching around an applique motif the second time in a new color
Stitching a vein in a leaf freehand
The same motif from a different angle. Here you can note the leaf point with two rows of stem stitch in two colors, gives a nice effect I think.
The Tie Off: I like to bury my threads in the back of my work as often as possible. You can see that I do tie a knot at the beginning (to the left and below the point of the needle in the photo). When I’m done with the color I’m using or have completed my motif, I bring my needle and thread to the back of the work. Doing a shallow running stitch (make sure you don’t pierce the motif and have your knot show in the right side of your work) I work the needle through the ground fabric a couple stitches.
I turn my work and stitch back along those same few stitches so that I sew the thread to itself. This is a very sturdy tie off.