This closely related segregate from ambrosioides is widely scattered across southern states, but perhaps mostly adventive except along the Atlantic and Gulf Coastal Plains (FNA 4, W). The only records from Ky are due to C.W. Short (BRU, and perhaps other herbaria); see also Short et al. (1833),but without locality. This taxon differs from ambrosioides as follows (FNA 4): inflorescence with leaves absent or shorter than the glomerules, up to 2-2.5 mm long (versus well-developed throughout, up to 25 mm long); glomerules 2.5-3.3 mm wide (versus 1.5-2.3 mm); perianth segments glabrous (versus glandularpubescent); seeds 0.6-0,8 x 0.8-1 mm (versus 0.6-1 x 0.4-0.5 mm), smooth (versus rugose to smooth).