Native. Annual. Propagates by seeds. Time of bloom: July to September. Seed-time: August to October. Range: Cape Breton Island to Ontario and Minnesota, southward to Florida and Nebraska. Habitat: Thin meadows, upland pastures, and in open woods about old stumps.
The oil distilled from this herb is much used in making the "mosquito dopes" which hunters and fishermen and many other persons are obliged to use in localities where mosquitoes are a plague; the plant is also used medicinally and the leaves and flowering tops, collected in full bloom and dried, are worth one to three cents a pound. In taste and odor the plant is very like the true Pennyroyal, which is European.
Stem erect, square, very slender, softly hairy, much branched, six inches to a foot in height. Leaves a half-inch to an inch long, thin, oblong-ovate, sparingly toothed, obtuse at apex, and narrowed to short petioles. Flowers in small axillary clusters, on short, hairy peduncles; calyx hairy, the three upper teeth triangular, the two lower ones awl-shaped; corolla lavender or pinkish, about a quarter-inch long, the upper lip merely notched but the lower one three-lobed and spreading; perfect stamens two, rising against the upper lip, with two rudimentary ones below. The four nutlets within the persistent calyx, very small. (Fig. 249.)
Fig. 249.-American Pennyroyal (He-deoma pulegioides). X 1/2.
Meadows infested with the plant should be cut before the seeds develop. Cultivation and enrichment of the soil, where practicable, soon enables better plants to crowd out the weed.