In its broad sense this widespread eastern species is highly variable, including polyploids (Wallander 2008, Nesom 2010c, W). Nesom revived division into three species: americana (2n = 46), smallii (supposed 2n = 92) and biltmoreana (2n = 138). All three taxa differ from other eastern ashes in their minutely papillose-reticulated, waxy-whitened lower leaf surfaces. Hybrids between the americana group and the pennsylvanica group are often suspected, but there is no conclusive evidence from the wild in Ky. (A cultivar "Cimmaron" is sometimes considered to be of hybrid origin but it appears to be americana.) Nesom found virtually no indication of hybrids anywhere, based on examination of many herbarium colls. Yet a few vegetative specimens (< 1%) cannot be confidently assigned; leaves of americana that are relatively young (Apr-May), less-stressed or more shaded seem to have less waxy lower leaf surfaces. Even slightly whitened lower leaf surfaces, with veins often less whitened, may indicate the americana group. F. americana, sensu stricto, has a relatively northern range, being rare to absent on the southeastern Coastal Plain. It differs from the other two taxa in its generally smaller fruits (mostly 25-32 mm long versus 33-54 mm), deeply notched petiole bases usually wrapped around buds (versus shallow-notched to truncate, the sides no more than level with tops of buds), usually glabrous leaves except along major veins (at least in Ky.), and usually glabrous twigs (versus glabrous or hairy). Its leaves tend to be smaller, on average, with upper surfaces usually plain yellowish-green (versus bluish) and less glossy. In Ky. confirmed records of americana, sensu stricto (mapped as solid symbols), are most abundant in the Bluegrass region plus surrounding Knobs. Typical americana appears to be less widely abundant in western regions of Ky. and Tenn., except along larger valleys of the Cumberland Rv. and Tennessee Rv. (Nesom 2010c).