| Sitanion longifolium J.G. Sm., 1899 |
| Sitanion marginatum Scribn. & Merr., 1902 |
| Sitanion minus J.G. Sm., 1899 |
| Sitanion molle J.G. Sm., 1899 |
| Sitanion montanum J.G. Sm., 1899 |
| Sitanion pubiflorum J.G. Sm., 1899 |
| Sitanion rigidum J.G. Sm., 1899 |
| Sitanion strigosum J.G. Sm., 1899 |
| Sitanion velutinum Piper, 1903 |
| Sitopsis (Jaub. & Spach) Love, 1982 |
| Sitospelos Adans., 1763 |
| Soderstromia C.V. Morton, 1966 |
| 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 |