This diploid (2n = 16) occurs in open swampy woods, seeps and wet meadows on acid soils in Appalachian regions, northeastern states and across southern Canada. There are also disjunct populations as far south as the Coastal Plain (K). In Ky. it is rare, with most records from remnants of significant wetlands in Appalachian regions or nearby (with a cluster centered on PULA). The outlying western coll. from CALL (MUR) was initially misidentified as A. praealtus: R. Athey #5132, 14 Oct 1985, Backusburg, West Fork of Clarks River at Ky 464, in pond bordering river.