Slide 26: a cross section of phloem tissue, including fibers, is at the top of the slide. The phloem fibers and the phloem cells nearest the fibers are primary phloem, those closest to the vascular cambium were produced by the cambium and are therefore secondary phloem. The vascular cambium lies at the junction where the staining changes from green and red to red. The xylem cells just below the cambium are produced by the cambium and are secondary xylem. The primary xylem can be easily located on this slide because the cells have very large lumens and are closer to the pith. Notice that the tissue on either side of the vascular cambium is secondary tissue produced by the cambium. Where would the ray initials of the cambium be located? ...the fusiform initials?