Petiole is the short cylindrical part of a leaf. It attaches lamina to the stem. Petiole helps to twist the leaf towards the sun. It allows the transport of the energy synthesized in the leaf to the rest of the plant. It also enables the transport of nutrients and water to the leaf.
In some plants leaves do not have petiol, thery directly arise from the leaf base. The leaves that do not have a petiole are called sessile or epetiolate leaves.