It's either called Ceylon stitch or in this case, Vandyke stitch with the single loop in the middle as you see in the picture (see here for genuine unadulterated Ceylon stitch). I think it's called Loop stitch too. Depends upon where you look. The tree trunk is Stem stitch, worked up and down, then Buttonhole stitched over the top. Oh, and a few stray Knots for fruit.
I've decided to call these knots Pekin Knots, which is the true name, excepting I've wrapped a few times. I grew up when French Knots were single wrap Bullion stitches, and they sit differently. Colonial Knots do that figure-eight thing. Pekin Knot is truly, really correct.
My decision is final and no correspondence will be entered into.