Pennyroyal (Mentha pulegium) is a perennial herbaceous plant native to the United Kingdom, belonging to the Lamiaceae family. Historically, it was more common in the UK, but now it is relatively rare and often considered an introduced species in some regions.

Pennyroyal thrives in nutrient-rich, moist to wet soils, often favouring habitats with full sun or partial shade. It can be found in various locations such as marshes, riverbanks, ditches, and damp meadows across the UK.

Predators of Pennyroyal include herbivores such as grazing mammals and insects, which may feed on its foliage. However, its strong aromatic scent, attributed to the presence of essential oils like pulegone, often acts as a deterrent to browsing animals.

As a perennial plant, Pennyroyal can live for several years, forming spreading mats of creeping stems and producing clusters of small purple flowers in summer. It reproduces via seeds and also spreads vegetatively through rhizomes, allowing it to colonise suitable habitats.

Culturally, Pennyroyal has been historically used for its medicinal properties, particularly as a herbal remedy for digestive issues, menstrual cramps, and as an insect repellent. However, it is important to note that Pennyroyal can be toxic if ingested in large quantities and should be used with caution.

An interesting fact about Pennyroyal is its association with folklore and superstitions. In some cultures, it was believed to have magical properties, such as warding off evil spirits or promoting luck and prosperity. Additionally, it was used in traditional herbal medicine as a natural insecticide and to repel fleas and other pests.