Light micrograph of a transverse section through a privet (Ligustrum sp. ) leaf, showing the vascular bundle which runs through the centre of the main vein. The vascular bundle is composed of xylem (pink), which supplies the leaf with sap from the roots, and phloem (green, immediately below the xylem), which carries away the products of photosynthesis for distribution to the rest of the plant. The elongated, column-like cells lying just below the ventral (upper) epidermis at (left & right of the central vein) are known as palisade cells, and are the principal sites of photosynthesis. Magnification: x50 at 35mm size.