Talk about leaves of vascular plants.

Intercept light, exchange gases and provide site for photosynthesis, some also store food and water, provide support or form new plants. Leaf has flattened blade and attached to twig by petiole. Within it there are veins, each angle between petiole and stem is called axil and contains bud. Arrangement of veins (venation) may be pinnate (one primary and many secondary) or palmate (several primary) or parallel.