Mapping here is tentative. B. burkii is a biennial known mostly from the central Appalachians west of the Blue Ridge, from e. Tenn. to c. Pa. (K). It has recently been redefined as a distinct species by Windham & Al-Shehbaz (2007; FNA 7, W). However, the status of its disjunct records in c. Ky. remains somewhat uncertain. There has also been some confusion between burkii and plants of the shale barrens in Va. and W.Va. that are now known as B. serotina (Steele) Windham & Al-Shehbaz. B. burkii reportedly differs from typical laevigata as follows (F, FNA 7, W): cauline leaves usually numbering 18-28 (versus 7-15); mid-cauline leaves not auriculate or sagittate-clasping at the base (versus clearly auricled or sagittate-clasping), entire to subdenticulate (versus serrate-dentate or entire); petals mostly 0.5-0.7 mm long (versus 1-1.5 mm). Plants mapped here need further study; they may be better treated as a distinct narrow-leaved variant of laevigata, but still somewhat auriculate, perhaps typical of less calcareous soils with more shale or dolomite (F. Levy, pers comm.)..