Conifer needle. Coloured scanning electron micrograph (SEM) of a section through a needle (leaf) from a conifer tree, showing the vascular bundle (large round cluster). The vascular bundle consists of xylem (small orange openings, centre) and phloem (pale yellow, surrounding the xylem) tissues. Xylem transports water and mineral nutrients from the roots throughout the plant and phloem transports carbohydrates and hormones around the plant. Magnification: x400 when printed 10 centimetres wide.