The Pineapple stitch is named for its resemblance to the skin of a pineapple.
It is a highly textured filling stitch worked in three sections. It can be worked in a single color (left) or two colors (right).
The first section is a group of vertical long stitches, which are latered by a standard cross stitch, finished with a tacking stitch over the intersection of the cross stitch.
While it may seem complicated at first glance, it's actually very easy to work. A perfect project to try using this stitch is the Pineapple Pattern, which includes a stitching diagram.
The link to print the Stitch Journal page can be found in Step 3.