The Petiole is the stemlike part of the leaf that joins the blade to the stem. Within a petiole are tiny tubes that connect with the veins in the blade. Some of the tubes carry water into the leaf. Others carry away food that the leaf has made. In many trees and shrubs, the petioles bend in such a way that the blades receive the most sunlight, thus assuring that few leaves are shaded by other leaves. The petiole also provides a flexible "handle" that enables the blade to twist in the wind and so avoid damage.
In some plants, the petioles are much larger than the stems to which they are attached. For example, the parts we eat of celery and rhubarb plants are petioles. In contrast, the leaves of some soft-stemmed plants, particularly grasses, have no petioles.