(a) : The vascular tissue of the root is characterised by radial arrangement of vascular bundles i.e., xylem and phloem occur in separate patches on alternate radii. The number of xylem and phloem groups vary from two to six. But tetrarch condition (four vascular bundles) is more common. Monocot root generally has more than six vascular bundles (polyarch). Vascular bundles in dicot stems are conjoint, collateral or bicollateral, endarch and open. They are arranged in a ring. In monocot stems the vascular bundles are conjoint, collateral, endarch and closed. They are scattered in the ground tissue.