fern stitch is a simple stitch that can be used to make vines, stems, branches, and other types of foliage.
it's made up of three straight stitches worked in a group. all three stitches will share the same end point. you'll work multiple groups of three stitches downward to form a line.
you can use fern stitch along a straight or a curved line. you might keep your line of fern stitches very uniform and symmetrical, or you might make it more organic and freeform by varying the angles, lengths, and spacing of your stitches.