Cross section in a petiole of grape – Vitis vinifera.

It is a paraffin section (10 µm thick) stained with safranin and alcian blue. The petiole contains a ring of vascular bundles (red arrows) and two small additional vascular bundles (white arrow). The parenchyma (par) in the center of the petiole is constituted of larger cells than those of the peripheral parenchyma, located below epidermis.

Below part of the section illustrating the different tissues in a vascular bundle: the xylem towards the center of the petiole and the phloem towards the outside. From the centre towards the periphery we find successively the xylem 1 (x1), the xylem 2 (x2), the cambium (c), the phloem 2 and 1 (Phl 2, Phl 1).