Rebbi Ilaye mentions Arkabalin as being suitable for Maror on Pesach. This plant is mentioned in Mishnayos Shevi’is and is listed (according to some Girsa’os) amongst plants which are not Ma’achal Adam (meant for human consumption). Since the passuk states the word ‘Achila’ by Maror, how can one be Yotze the mitzvah of Maror with something not fit for eating?