DR KEITH WHEELER / SCIENCE PHOTO LIBRARY DR KEITH WHEELER / SCIENCE PHOTO LIBRARY
Elm stem (Ulmus procera) cross-section, polarised light micrograph. At centre is the pith (blue), outside of which is a ring of wood (brown/yellow), indicating that the stem is one year old. It contains xylem vessels (large holes), which transport water and minerals throughout the plant. The green/red ring is the cambium, and above this is a second woody ring (yellow) containing phloem vessels, which transport carbohydrates and hormones around the plant. The outermost layer is bark, consisting of cork. Magnification: x44 when printed 10 centimetres wide.
Model release not available. Property release not required.