This widespread eastern species appears to intergrade with communis and affinis at some sites; see notes under those names. There also appear to be occasional hybrids with hirsutula, palmata (= triloba) and other species. Leaf pubescence is usually the most obvious difference from communis, with sororia persistently pubescent on both leaf surfaces (versus generally glabrous or glabrate except sometimes for petioles or basal parts of blades); leaves are often relatively dark green and generally lack purplish hues. However, to quote H. Ballard (in prep.), sororia is : "A heterogeneous melange of incompletely understood extremes sharing glabrous spurred petals, obtuse to rounded sepals, short rounded auricles not elongating in fruit., and purple-spotted or -blotched cleistogamous capsules on very short prostrate to arching peduncles... Hybridizes with every Boreali-Americanae species growing locally sympatric with it." He has indicated that a confusing glabrous variant of sororia is widespread in Appalachian regions and mid-Atlantic states (Ballard et al. 2023).. Further west, this glabrous variant appears to merge into V. pratincola Greene (which is distinguished by dark seeds with darker blotches). In cooler regions, it may be more difficult to separate sororia from commuis, and plants known as V. septentrionalis Greene can appear intermediate (Cr, W)). However, Ballard et al. (2023) has treated septentrionalis as a distinct boreal species. Another largely glabrous variant has been called "hirsutula-like", with purplish rounded leaves; this may be largely restircted to central Appalachian regions (W; Ballard et al. 2023).