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 into northeastern states (W). A coll. from TRIG (APSC) has been referred to this segregate, and other colls. of Polanisia need review.