Peppermint, a hybrid of watermint and spearmint, is a perennial plant. The essential oil comes from the aerial parts of the plant (everything above the ground). When peppermint is ready to harvest, it is cut down to the ground, then left in the field for a few days to dry. It is then chopped up before distillation. About one pound of peppermint leaves produces one 15 ml bottle. During autumn, the material left over from distillation is used as mulch.