#60 Distribution of Xylem and Phloem in roots, stems and leaves

Root

In the roots, xylem and phloem are in the centre to withstand stretching forces. 

In the stems, they are arranged in bundles near the edge to resist compression and bending. 

Stem

They are grouped together into veins and vascular bundles as they pass through leaves.

Leaf

The positions of xylem and phloem tissues as seen in transverse sections of unthickened, herbaceous, dicotyledonous roots, stems and leaves: