Mapping here is provisiional. This species of east-central states is close to cordifolium and often confused. There may be frequent hybridization with cordifolium and drummondii, perhaps to lesser extent, undulatum and shortii, see notes under those species. In some recent treatments, circumscription of urophyllum has been tightened, with only diploids documented (2n = 16); compare FNA 20 with Cr. S. urophyllum has a wide range similar to cordifolium, but it is less common to rare in southeastern states. It is typical of more open, drier or disturbed habitats, where it appears most distinct. S. urophyllum is distinguished from cordifolium by its rays usually pale blue to white/cream (versus usually blue-purple), phyllaries with relatively long green blazes (L/W ca. 4-5 versus 2-3 and purplish); lower to mid-cauline leaves shallowly cordate to truncate (versus cordate) and shallowly toothed (versus sharply).