Use: Probably the best use of pennyroyal is as an insect repellent. Crush pennyroyal leaves and rub them into your skin to keep away flies, mosquitoes, gnats, and ticks. Pennyroyal will leave a pleasant mint-like fragrance on your skin. Many commercial repellent spray and lotions contain pennyroyal oil. Pennyroyal is also an effective bug repellent for cats and dogs and has been used since Roman times as a flea repellent. Pennyroyal was a popular culinary herb in Britain for centuries. The leaves were put in puddings, mixed with stuffings and used in meat sauces. it is no longer considered a culinary herb, although a few herbalists sometimes still use it in tea concoctions. Warning: Pennyroyal is toxic and was taken off the list of official drug plants, and should not be ingested for home remedies, and especially not during pregnancy. Ornamental: Pennyroyal is a creeping mint that spreads quickly and sends up pretty 6" bluish lilac flowers. Use the plants between stepping stones, in rock gardens, for edgings or groundcovers. It's probably a little too weedy to use in a formal garden. Culture: Pennyroyal is easy to grow and thrives in moist, shady or sunny locations.