Mentha pulegium, commonly (European) pennyroyal, or pennyrile, also called squaw mint, mosquito plant and pudding grass, is a species of flowering plant in the Lamiaceae family, or mint family, native to Europe, North Africa, and the Middle East.
Pennyroyal is toxic to humans and has differing effects dependent on the volume and concentration ingested. The most concentrated and toxic form of the pennyroyal plant is pennyroyal oil. The oil contains 80% to 92% of cyclohexanone pulegone. Pulegone, the molecule in highest concentration in the pennyroyal plant, causes a variety of ailments in those who ingest it and is what causes the plant to have its peppermint flavour.