This largely Mexican species has been confused with the more widespread southwestern species, D. wrightii Regel. D.inoxia may differ as follows (W): corolla limbs with 5 acuminate lobes more or less equal to 5 lobules (versus longer); calyces and lower leaf surfaces villous-pubescent, especially along veins (versus canescent-pubescent), the hairs on leaves spreading (versus short-appressed or curved). Both taxa may be scattered in southeastern states, or they may not be distinct enough to separate (W). There are colls. from FAYE (KY), PIKE (M) and perhaps elsewhere in Ky., but these may only be from rare garden escapes.