Y lettuce on Passover?

Rabbi Ahawa the son of Rabbi Ze'ira has an interesting take on why we use lettuce for seder. Rabbi Ahawa explains just as lettuces is sweet at the beginning (the leaf) bitter at the end (the stalk), as so were the Egyptians sweet to the Israelites in the beginning and bitter at the end. For example: Genesis 47:6 reports Pharaoh told Joseph," the land of Egypt is before; you have your father and brother dwell in the best of the land". Then towards the end the Egyptians became bitter towards the Israelites . As Exodus 1:14 says "and they (the Egyptians) made their(Israelites)lives bitter". In "the big picture of life" it was the Egyptian's bitterness (hating) that ultimately push the Israelites towards greatness. Rather it's sweet or bitter the experiences of life are pushing you towards greatness!