DR KEITH WHEELER / SCIENCE PHOTO LIBRARY DR KEITH WHEELER / SCIENCE PHOTO LIBRARY
Dahlia stem. Light micrograph of a section through the primary stem of a Dahlia (Dahlia sp.) plant, a typical dicotyledon. From the outside in: epidermis with cuticle (black); underneath the epidermis is lamella collenchyma (black) and a cortex of parenchyma cells (blue); next is a ring of separate vascular bundles made up of the outer phloem and xylem fibres (red); oval-shaped phloem (blue) tissue; single layer of cambium tissue; xylem vessels (red and white). Between the vascular bundles are files of parenchyma cells called medullary rays. At the centre of the stem is the pith of parenchyma cells (red). Magnification: x13 when printed 10 centimetres wide.
Model release not required. Property release not required.