Polarised light micrograph of a transverse section through the root of Iris germanica, a monocotyledon, showing the central vascular tissues. Xylem vessels appear in section as the large purple areas that surround a central pith. Phloem vessels are smaller & are located between the xylem and the endodermis which surrounds the vascular tissues. Xylem vessels carry water & minerals absorbed by the root to the rest of the plant whilst phloem vessels carry sugar in the reverse direction, from leaves to root. The large outer cells form the root cortex. Magnification: X 25 at 35mm size, X50 at 6x7cm size.