This species occurs mostly in marshes from New England through the Great Lakes region to the upper midwest; 2n = 30. C.W. Short made colls. (CINC, formerly KY, check PH) in 1835 from "lakes in the barrens of Ky.", probably in CHRI, TODD, LOGA or WARR. There is also a coll. from FULT (US) made in 1915, and Gattinger (1901) reported it from "Guthrie, Ky" (TODD) as well as "near Humboldt, W. Tenn." (Gibson Co.). These records are probably all referable to the largely midwestern var. interior, which is generally more robust than typical palustris, but that identifcation remains somewhat uncertain.