Treatment remains tentative. This midwestern taxon has been re-evelated to species status in W; see also Folk (2015) and Engle-Wrye & Folk (2026) But many plants have been considered by some authors (e.g. Wells 1984, Cr, FNA 8) to have resulted from introgression with the more western species, H. richardsonii R. Br. It was not recorded from Ky. by Wells, but the identification of colls. mapped here is confirmed. There is also an unmapped coll. from MADI (BEREA) that is misleading; it comes from cultivation of buried seed, "with forced flowering" (R. Thompson & Wade #87-2033), and its origin is unclear. Compared to typical americana, hirsuticaulis is said to differ as follows (W): petioles densely hirsute (versus glabrous to sparsely hirsute); free hypanthium 1.1-1.9 mm long with mean 1.5 mm (versus 0.6-1.5 mm with mean 1.1 mm), However, recent analysis of Engle-Wrye & Folk (2026) has indicated that plants of the southern Interior Low Plateaus (especially w. Ky. and w. Tenn.) are closer to H. americana var. brevipetala, as their "(South)" segregate. Yet they did not detail morphological differences between their South and North segregates. They supported the view "that the widespread and morphologically variable H. americana var. hirsuticaulis should remain recognized as a hybrid taxon closer to H. americana." An alternative view might be that there is a more or less continuous cline of increasing pubescence and larger flower size from southeastern states (especially caroliniana) towards to the northwest (especially richardsonii).