DR KEITH WHEELER / SCIENCE PHOTO LIBRARY DR KEITH WHEELER / SCIENCE PHOTO LIBRARY
Sunflower stem. Light micrograph of a transverse section through the stem of a sunflower (Helianthus annuus) plant. At the centre of the stem is a large area of pith, consisting of parenchyma cells. Around this is a ring of vascular bundles. Each bundle contains phloem (dark blue tightly packed cells) and xylem (dark blue with white lumen) cells, which transport carbohydrates and water around the plant respectively. Magnification: x14 when printed at 10 centimetres wide.
Model release not available. Property release not required.