This hexaploid (2n = 48, or rarely 56) is known from most northeastern states, especially mid-Atlantic, New England and eastern Great Lakes region (but perhaps not Iowa, Mo. or Tenn.); it is defined here to include S. pilosum var. pringlei (Gray) Nesom of some recent treatments (e.g. Semple & Chmielewski 1985, FNA 20; see also, Ladd & Thomas 2015). The only clear difference from typical pilosum is its largely glabrous condition, except for cilate leaf margins. Also, inflorescence branches tend to be more ascending and condensed (thyrsiform to subcorymbiform versus divergent to virgate-spreading in F). However, there is little documented intergradation and habitats are generally distinct. S. juniperinum is typical of dry calcareous sites, forming relatively large uniform populations. In Ky. it is largely restricted to base-rich soils (often dolomitic) among the Knobs and other hills around the Bluegrass region. More robust plants with larger heads predominate in Ky., and were previously treated by F and others as A. pilosus var. demotus S.L. Blake. Var. pringlei has generally smaller dimensions, but might just be an environmental phenotype associated with "alvars" and similar habitats further north (FNA 20; J. Semple, pers. comm.). Further research is needed to determine if two taxa should be recognized. S. juniperinum is most similar to two smaller-headed species: S. depauperatum (Fern.) Nesom, a rare diploid of serpentine glades from N.C. to Pa.; and the largely diploid S. parviceps (Semple et al. 1993; and see above under this ame). It is also similar to the more southern octoploid, S. priceae (see below). But there is little overlap of ranges among these taxa, and although there is considerable variation within juniperinum, suspected introgression with other taxa has not been proven (J.C. Semple, pers. comm.).