Mapping is provisional. After 30 years of work in the field and herbarium, B concluded that no reliable separation of pycnanthemoides, loomisii and incanum is possible, and subsequent botanists in Ky. have generally shared this view. However, Chambers (1993) and others have insisted that pycnanthemoides is a distinct tetraploid species (2n = 72), with a largely Appalachian range but also extending to s. Ill., w. Ky. and perhaps n. Ala. See also notes under incanum, which has a similar range but more widely recorded. Remarkably, neither species is currently recorded from west of the Mississippi Rv. or in most of Miss., where they appear to be replaced abruptly by albescens (K),