False-colour scanning electron micrograph of a cut stem of the white dead nettle, Lamium album. The hollow centre is produced by the collapse of thin- walled pith cells. Surrounding this core is a layer of unspecialised cortical cells - the cortical parenchyma (yellow & blue). vascular bundles (red) serve to conduct water & nutrients: one near each of the 4 corners, & one half way along each side of the stem. In the extreme corners of the stem, the best position mechanically, small collenchyma cells (green) are visible. The hairs on the outside of the stem are designed to discourage insects from climbing the plant. Magnification: x10 at 6x4.5cm size. Reference: MICROCOSMOS, figure 4.6, page 70.