This western taxon has been treated as a large flowered subspecies or variety of dodecandra by H.H. Iltis (FNA 7). In Mo. there is much intergradation and little overall difference in range or habitat (Y). But trachysperma is reportedly more weedy and perhaps only adventive in northeastern states (W). Colls. from a railroad in ESTI (VB) and from lakeshores in TRIG (APSC) have been referred to this segregate. All colls. of Polanisia from Ky. need review.