Heterotheca villosa (Pursh) Shinners is includes a complex assemblage of morphotypes, some nearly allopatric ranges and others with mostly overlapping ranges.  Races are distinguished on the basis of leaf shape, hair density and gland density.  Most races occur at both the 2x and 4x level which increases the ranges of morphological variation. Numerous intermediates occur between the varieties listed below following Semple (1996, 2006).  Alternative classifications have been published by Cronquist and Nesom in regional floristic treatments and by others over multiple decades.