Northern Prairie Wildlife Research Center
Occurring nearly throughout North Dakota except for a few north-central counties bordering Canada, rough false pennyroyal ranges elsewhere from Ontario to Alberta and south to Mississippi and east Texas at elevations up to 5500 ft.
The plant is a small, hairy annual that grows up to 14 inches tall, but most North Dakota specimens are only 6 to 8 inches tall. Leaves are very narrow, less than an inch long, and crowded at the upper part of the plant. The tiny (1/4" long) flowers are lavender to bluish-white and occur in small groups of three to six opposite each other near the leaf axils. Fruits consist of four one-seeded nutlets with a hard cover.
Look for rough false pennyroyal in dry soils in native grasslands or along roadsides. Heavy grazing seems to improve the habitat for this species, likely through exposing soil for seed germination and reducing competition from other plants. The dried leaves of some Hedeomas are used for colds and stomach disorders, but H. hispidum is not mentioned in this regard. Little is known about economic uses for many of the plants in the Great Plains because there are so few historical records.
Rough false pennyroyal is a member of the mint family (Lamiaceae) which contains about 3,500 species worldwide. Mints are well known for producing a large variety of oils such as lavender, horehound, and thyme used in perfumes and flavorings. Catnip is also in the mint family. The generic name Hedeoma is derived from the Greek hedys, "sweet", and osme, "scent". There are about 25 species of this genus in the Western Hemisphere. The specific epithet hispidum means "with short stiff hairs" in botanical Latin. Rough false pennyroyal was first described for science by the German botanist Frederick Pursh in his monumental Flora Americae Septentrionale of 1814.