This is widespread in central North America, with extensions to Pacific and Atlatic coastal states in the cool temperate zone (FNA 24). In eastern regions, canadensis has often been confused with glabriflorus, riparius, virginicus (especially var. intermedius) and others. The few known Ky. colls. are from banks of the Ohio Rv. or Mississippi Rv., or within a few miles of these rivers. All colls. except the one from HICK (JC) are were made before 1950. E. canadensis is sometimes planted with seed-mixes from more western prairies, and records from probable plantings are excluded here. E. canadensis is highly variable but segregates are not well-defined. Most Ky. colls. are referable to the midwestern var. robustus (Scribn. & J.G. Sm.) Mackenzie & Bush, which may result from introgression with virginicus or glabriflorus (FNA 24). But the coll. from JEFF (DHL), along a railroad, resembles the more southwestern var. brachystachys (Scribn. & Ball) Farw.