This tetraploid (2n = 32) is a comsopolitan, variable biennial or short-lived perennial of shorelines and wetlands. Flowers can be larger than described in some sources, with petals up to ca. 4 mm long. Proposed segregates may not be clearly distinct (Al-Shehbaz 1988b; FNA 7). In Ky. colls. have often been referred to the widespread North American var. fernaldiana (Butters & Abbe) Stuckey, but the Eurasian var. palustris also appears to be present, and further study is needed (W). Var. palustris reportedly differs in its less robust habit but generally longer siliques (4-9 mm versus 2.5-5 mm). Plants from EDMO and SCOT (KY) appear at least transitional to the native northern segregate, var. hispida (Desv.) Rydb. Hybrids with sinuata and sylvestris can also be expected (Y, FNA 7), and may be suggested by the relatively large flowers in some plants.