Venation

The lamina, or leaf blade, is the green expanded part of the leaf and is traversed by veins and veinlets. Venation is the term used for the arrangement of these veins and the veinlets in the lamina of the leaf. Veins are important because they provide rigidity to the leaf blade and act as channels of transport for water, minerals and food materials; usually there is a middle prominent vein known as the midrib from which the smaller veins branch out. On the basis of how these veins are laid down in the lamina, two principal patterns of venation are recognised.

• Reticulate venation — when the veinlets branch and rejoin to form a network within the lamina, the venation is said to be reticulate. This meshwork of veins spreads irregularly across the blade. Reticulate venation is generally found in the leaves of dicotyledonous plants, which typically possess this pattern. …