STRAIGHT STITCH
 
This stitch is a surface embellishment stitch, and is made on the tops of the pleats.  In other words, points A and B must both be positioned at the peak.  This causes a little awkwardness in positioning the stitch; sometimes starbursts don’t quite look as even as they would on flat fabric.

Whereas most smocking stitches involve the needle passing through at least one full pleat (two layers of fabric), with the straight stitch you just stab the needle straight down.