Light micrograph of a transverse section through a six year old lime tree (Tilia sp.) stem. The image shows the pith (dark, centre), six annual rings of xylem (multicoloured area surrounding pith) & an outer layer (cortex) containing roughly-triangular areas of phloem (green), striped with pink phloem fibres. The xylem is composed of vertical, tube- like cells which conduct the sap upwards from the roots. It contains a radiating system of vascular rays (dark lines), which supply it with nutrients. The phloem is responsible for the distribution of the carbohydrates produced by photosynthesis in the leaves. Magnification: x3 at 35mm size.