Hedeoma pulegioides (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 15–30 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, hermaphroditic, produced in small clusters; it flowers from mid to late summer.
Other names are mock pennyroyal, squaw mint, tickweed, stinking balm, mosquito plant, American falsepennyroyal, and American false pennyroyal.
The name pulegioides is derived from the Latin pulegium and oides, and means "like pennyroyal". Hedeoma pulegiodes is also known by the synonyms Melissa pulegioides L. (basionym), Cunila pulegioides (L.) L., and Ziziphora pulegioides (L.) Desf.
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.