Hedeoma pulegioides

Hedeoma pulegioides (American Pennyroyal, or American False Pennyroyal^[1]) 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.^[2]

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.^[3]

Other names are mock pennyroyal, squaw mint, tickweed, stinking balm, mosquito plant, American falsepennyroyal, and American false pennyroyal.^[4][3]

The name pulegioides is derived from the Latin pulegium and oides, and means “like pennyroyal“.^[5] Hedeoma pulegiodes is also known by the synonyms Melissa pulegioides L. (basionym), Cunila pulegioides (L.) L., and Ziziphora pulegioides (L.) Desf.^[1][6]

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.