Bean leaf. Light micrograph (LM) of a transverse section through the leaf (pinna) of a bean plant. A bean is the seed of one of several genera of the dicotyledonous flowering plant family Fabaceae, which are used as vegetables for human or animal food. Present is a central vascular bundle made up of phloem sieve cells (blue) 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.