Root section. Coloured scanning electron micrograph (SEM) of a section through a root of a woody dicotyledon plant. This root consists of secondary xylem tissue (yellow, centre), secondary phloem tissue (cream, surrounding the xylem) and an outer cork (green). The xylem contains many vessels that transport water and mineral nutrients from the roots throughout the plant. The phloem transports carbohydrates and plant hormones around the plant. The cells of the cork are reinforced with lignin, which helps to maintain structural support. Magnification: x80 when printed 10 centimetres wide.