American Pennyroyal - Another Native Groundcover

While it may be a little late in the season to talk about starting annuals from seed, but I thought American Pennyroyal was worth mentioning here. It is a tough little plant that grows in dry, partly shady locations and is quick and easy to germinate.  It has a low-growing (6-12”) and spreading habit qualifies it as a native groundcover.

American Pennyroyal, Hedeoma pulegioides, is a low growing herb of the mint family that has been used extensively by both Native Americans and the colonists for its medicinal properties. Medicinal uses include treatment for colds and fevers, as a gastrointestinal aid (‘warming to the stomach’), and as flavoring agent in foods, like tea and ice cream. The colonists readily accepted this herb as a replacement for the European or English pennyroyal (Mentha pulegium) that they were accustomed to using. The plant is rich in a pungent, volatile oils including pulegone (whence the species name), which holds most of the medicinal properties; however, large doses are reportedly lethal. For the hikers, rubbing the leaves on your skin repels mosquitos and other biting insects.

The plant grows in dry upland woods and can occur as rather dense colonies. In nature, it is often found growing in openings in the woods and along paths. The native range runs all along the East Coast (except Florida) and west to Oklahoma and North Dakota.
Small blue tubular flowers are borne in the leaf axils of the erect stems from July to September. While the flowers do attract some tiny insects, they are difficult to see unless you get down on your hands and knees.

The real garden value of this plant is in its aromatic character and its ability to grow thickly in dry partly shady conditions. I am putting it along walkways so that you get a burst of the minty aroma anytime it is disturbed, or stepped on. I started my first ‘crop’ in 2009, with seed from Companion Plants, and am seeing new colonies springing up in adjacent areas. It is easy to distinguish from other sprouts, because as soon as you touch it you get a whiff of its minty aroma. This is a good example of what I am looking for in a native annual, that is, an annual plant that is able to persist on its own without my direct involvement and has desirable garden traits. In the case of American Pennyroyal those are its stimulating aroma and ability to grow in dry partly shady locations.