Secondary Tissues in Stems

Secondary phloem tissue in stems is very similar to secondary phloem tissue in roots and is composed of the same cell types.
Secondary Phoem Sieve Tube Elements, Maceration

Secondary xylem tissue in stems is also very similar to that of roots. Two connected vessel elements are shown in the image at left. In addition to the end plates located between the two vessel elements, they also have lateral perforation plates. These plates allow water and minerals to move laterally through the tissue.

The granular material in the septate fibers is composed of amyloplasts-- starch storing plastids.


Secondary Xylem Vessel Elements and Septate Fibers.
At left is an image of pith parenchyma cells under polarized light.
Secondary Pith Parenchyma XS, Polarized Light.