Chain stitch is very versatile. It can be used as a filler or for lines, and in the freestyle embroidery project, I used it to make some long, skinny leaves.
I used two strands of floss and a slightly different shade of green. I started near the bottom of a stem, and just made a line of chain stitch. Like most freestyle embroidery, I didn’t draw a line to follow, I just did it by freehand.