This perennial diploid (2n = 24) occurs in southeastern states east of the Mississippi Rv. In Ky. virgatum is a somewhat conservative plant of southern regions, growing in remnants of open grassy woods or "barrens" on moderately dry, acid soils. It has been erroneously combined with the related diploid H. harperi R. Keller (centered on the Coastal Plain of Ga.) or the tetraploid H. denticulatum Walter (mostly along the Atlantic Coastal Plain), but nomenclature has now been clarified (W; Allison 2011). There is a coll. of typical denticulatum labeled as if from ROWA (MDKY), but this provenance is highly dubious (Campbell et al. 1992).