How leaves are classified on the basis of the arrangement of veins.
Leaves are classified into types, based on the arrangement of veins within the leaf lamina. This type of arrangement is called venation.
Reticulate venation – In this type, the veins and veinlets form a network. This type of leaves is present in dicotyledonous plants.
Parallel venation – The veins run parallel to each other towards the margin or the tip of the leaf. This type of leaves can be seen in monocotyledons.