This occurs mostly in southeastern states east of the Mississippi Rv., centered on Appalachian regions and the Interior Low Plateaus (K). Some colls. from Ky. are difficult to distinguish from the more midwestern brevirostra, and should be rechecked; see notes under that species. Typical S. engelmanniana (which is largely on the southeastern Coastal Plain) and the related S. cuneata Sheldon (which is largely in more northern regions) have also been reported from the state, but probably based on misidentifications (M). Despite uniform chromosome number in the genus (2n = 22), there is little evidence of hydridization among these species or others (FNA 22).