The image is that of a stain glass window in Chartres Cathedral which is in northern France. This ( and many others) gave rise to the idea of the Jesse Tree. Although it can take different forms, the essential idea is very simple. Jesus Christ, who we are waiting for, is son of David, he is a descendant of King David. The father of David was Jesse. The whole of the Old Testament is a longing and yearning for the coming of a Saviour and that is Jesus Christ.