| Elymus repens subsp. repens (L.) Gould, 1947 |
| Elymus riparius Wiegand, 1918 |
| Elymus robustus Scribn. & J.G. Sm., 1897 |
| Elymus robustus var. vestitus Wiegand, 1918 |
| Elymus simplex Scribn. & Williams, 1898 |
| Elymus simplex var. luxurians Scribn. & T.A. Williams, 1898 |
| Elymus sitanion Schult., 1824 |
| Elymus smithii (Rydb.) Gould, 1947 |
| Elymus spicatus (Pursh) Gould, 1947 |
| Elymus stebbinsii Gould, 1947 |
| Elymus subsecundus (Link) Á. Löve & D. Löve, 1964 |
| Elymus trachycaulus (Link) Gould ex Shinners, 1954 |
| Elymus trachycaulus (Link) Hoover, 1966 |
| Elymus trachycaulus subsp. subsecundus (Link) Á. Löve & D. Löve, 1975 |
| Elymus trachycaulus subsp. trachycaulus (Link) Gould ex Shinners, 1954 |
| Elymus trachycaulus var. trachycaulus (Link) Gould ex Shinners, 1954 |
| Elymus trachycaulus var. unilaterale (Cassidy) Beetle, 1984 |
| Elymus triticoides Buckley, 1862 |
| Elymus triticoides subsp. multiflorus Gould, 1945 |
| Elymus triticoides subsp. triticoides Buckley, 1862 |