European pennyroyal (Ger. Pole/) is derived from Mentha pulegium, L., (Pulegium vulgare, Mill.) or its hybrid varieties, and has been used medicinally since the middle ages3) and possibly earlier.4) The distilled Oleum pulegii is mentioned in the price ordinance of Frankfurt for 1582 and appears to have been used medicinally, like the plant and its distilled water, in the 16. and 17. centuries.