Eucalyptus leaf. Light micrograph (LM) of a transverse section through the leaf (pinna) of a eucalyptus plant. Eucalyptus is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family. This xerophytic (arid-adapted) leaf has a thick layer of cuticle made of wax with sunken stomata in order to reduce water loss. There are also large secretory (oil) cavities in the mesophyll. Present is a central vascular bundle made up of phloem sieve cells and xylem tracheids (red). Dicot leaves are dorsoventral as the upper and lower surfaces of the leaves are distinguished. The vascular bundle is large in dicot leaf whereas in monocot leaf, both small and large parallel vascular bundles are present. Magnification: x15 when printed at 10 centimetres wide.