You can see several diagonally arranged leaf bases that are light-colored.

The dark stripes of material are strips of remaining epidermis that was torn when the stem increased in girth. 

The photo at the bottom shows the cortical or bark layers. The stele is not present in this photo. 

The bulbous structures are leaf bases in cross sectino.  

The large white areas are partly due to poor preservation and partly the result of large air channels that typically accompany the leaf traces.