Plant · P-593

Pennyroyal

Mentha pulegium

Pennyroyal is a low, fast-spreading mint grown historically as a flea and rodent repellent, its leaves also used as a coarse, spearmint-like flavoring and tea. The plant is genuinely toxic in quantity - the essential oil in particular can cause abortion and is not safe in pregnancy, with overdose bringing on cramps, confusion and even hallucination, so it is treated as a poison rather than just a strong herb. It thrives on damp, even seasonally flooded ground in sun or partial shade, spreading by both seed and rhizome fragments so readily that it is rated invasive along waterways in some regions and is best kept off any wet ground that drains to a creek or wetland. Grown dry in a container or raised bed, it stays easy to manage.