| Soderstromia mexicana (Scribn.) C.V. Morton, 1966 |
| Sohnsia Airy Shaw, 1965 |
| Sohnsia filifolia (E. Fourn.) Airy Shaw, 1965 |
| Solenachne Steud., 1855 |
| Solenophyllum Baill., 1893 |
| Sorghastrum Nash, 1901 |
| Sorghastrum (Nash) Stapf, 1917 |
| Sorghastrum agrostoides (Speg.) Hitchc., 1911 |
| Sorghastrum albescens (E. Fourn.) Beetle, 1982 |
| Sorghastrum avenaceum (Michx.) Nash, 1901 |
| Sorghastrum brunneum Swallen, 1950 |
| Sorghastrum canescens (Hack.) Pilg., 1940 |
| Sorghastrum flexuosum Swallen, 1966 |
| Sorghastrum francavillanum (E. Fourn.) Hitchc., 1909 |
| Sorghastrum galeotii (E. Fourn.) Conz., 1946 |
| Sorghastrum incompletum (J. Presl) Nash, 1912 |
| Sorghastrum incompletum var. bipennatum (Hack.) Dávila, 1989 |
| Sorghastrum incompletum var. incompletum (J. Presl) Nash, 1912 |
| Sorghastrum liebmannianum Hitchc., 1913 |
| Sorghastrum linnaeanum (Hack.) Nash, 1903 |