This taxon is known only from somewhat calcareous subxeric glades and prairies in disjunct regions of the Carolina Piedmont, southern Appalachian foothills, adjacent Coastal Plain, and perhaps the southern Interior Low Plateaus; see W, Weakley et al. (2018, 2023) and their sources. B. aberrans appears somewhat intermediate between typical australis and B. minor Lehm., a species of the Great Plains; see notes under that name. As in minor, aberrans has relatively short stature with horizontally spreading branches, short petioles and small leaves. The flowers and fruits of aberrans are not as distinct from australis, and further research is need to compare populations. Weakley et al. (2018) stated: that aberrans "has the smallest flowers (in all measurements), the most widely divergent branching pattern, and is the only one of the three to regularly array all of the leaflets of a plant in a vertical plane as opposed to having them loosely and more horizontally disposed." In Ky., flowering dates are mid-May to early Jun, with seeds maturing mostly in July. flowers and fruits are similar in size to those of typical australis. However, given the striking disjunction in habitat from typical australis (on rocky river banks), species status is probably justified (W); similar biogeography exists in Physostegia praemorsa versus P. virginiana. There are only 4-5 populations of cf. aberrans in Ky. that are well documented. These sites are clustered in western sections of the Pennyrhile Karst Plain or its transitions, mostly in unplowed areas on low hills with some sandy or cherty fill in cracks between partially exposed blocks of limestone. The population in TODD (Highland Lick Rd 0.7 miles NW of Rt 181) is remarkable, with over 1000 plants. The old records from HOPK ("Madisonville" at KY-Agr., 16 May 1914, perhaps cultivated) and HARD (Wherry & Pennell #13659 at PH, 6 Sep 1927) are more tenuous. Without its distinctive blue flowers or its more elongated fruits, the australis complex (with aberrans) may still be distinguished from the alba complex (with leucantha) as follows (F, Isely1990): stipules conspicuous, longer than petioles, usually persistent at mid-stem (versus shorter than petioles, caducous); leaflets with L/W = 2-3 (versus 2-4.5).