Hedeoma pulegioides

Hedeoma pulegioides, also known as pennyrile, American pennyroyal, or American false pennyroyal, is a species of Hedeoma native to eastern North America, from Nova Scotia and southern Ontario west to Minnesota and South Dakota, and south to northern Georgia and Arkansas.

It is a low-growing, strongly aromatic herbaceous annual plant from 15 to 30 cm tall, with a slender erect much-branched, somewhat hairy and square stem. The leaves are small, thin, and rather narrow, with a strong mintlike odor and pungent taste. The flowers are pale blue, monoecious, produced in small clusters; it flowers from mid to late summer.

Other names are mock pennyroyal, squaw mint, tickweed, stinking balm, mosquito plant, and American false pennyroyal.

The term "pennyroyal" (or pennyrile, from a dialectal pronunciation) is also used to describe a geographic province of western Kentucky, the Pennyroyal Plateau, where H. pulegioides grew in profusion sufficient to lend its name to the whole area.