This species of east-central states is often confused with the more southern rufidulum. Hybridization appears to be rare but it has been clearly demonstrated at one site in Ky., based on DNA-sequencing (Spriggs et al. 2019). The leaves of prunifolium are relatively thin and dull (versus somewhat coriaceous and glossy), glabrous or slightly brown-scurfy below (versus red-scurfy). Also, it tends to spread from underground runners, sometimes forming thickets. Peak flowering is about 1-2(3) weeks earlier (mid-April versus early May) in Ky. and elsewhere where ranges overlap; but there is little or no difference outside the overlap (Donoghue 1980. Spriggs et al. 2019). Both species are concentrated on base-rich soils, but prunifolium occurs on more mesic sites. There has been much medicinal use, especially for reducing cramps; the active chemicals appear to be iridoid glucosides (Cometa et al. 2009).