Nicotiniana leaf. Light micrograph (LM) of a transverse section through the leaf (pinna) of a nicotiniana plant. Nicotiana is a genus of herbaceous plants and shrubs in the family Solanaceae, that is indigenous to the Americas, Australia, south west Africa and the South Pacific. Various Nicotiana species, commonly referred to as tobacco plants, are cultivated as ornamental garden plants. Present is a central vascular bundle made up of phloem sieve cells (green) 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.