This is virtually restricted to mesic woods on medium acid soils in central Appalachian regions, with a concentration in the northern Appalachian Plateaus, central Ridge & Valley, and central Blue Ridge. The only confirmed sites west of Appalachian regions are fromJESS (KY), on terraces of lower Jessamine Creek with beech trees on relatively acid, cherty alluvial soils; and an old coll. by R.Peter from FAYE at "Kentucky River, Rogers', at the Richmond Road" (MICH). Reports from Mammoth Cave National Park were based on misidentified Synandra hispidula (coll. of H. Lix at US). F's report from Ill. remains dubious. The pungent minty odor from crushed leaves is remarkable for a mesic woodland herb, and this species has had local medicinal use in Ky., including for relief of pain in teething children; a local name is "mountain catnip" (D. Barrett, pers. comm.). The chemistry of its volatile oils has been explored recently by Dein et al. (2020). Although the genus has only one species in North America, it has several in East Asia (Deng et al. 2015), where there has also been recent research into the special chemistry of this genus, with diverse spermidine alkaloidal glycosides (Murata et al. 2009) and novel phenolics (Murata et al. 2011). The genus is close to Glechoma, and overlaps in some chloroplast DNA markers (Deng et al. 2015).