| Steinchisma exiguiflorum (Griseb.) W.V. Br., 1977 |
| Steinchisma hians (Elliott) Nash, 1903 |
| Steinchisma laxum (Sw.) Zuloaga, 2003 |
| Stenochloa Nutt., 1848 |
| Stenochloa californica Nutt., 1848 |
| Stenofestuca (Honda) Nakai, 1950 |
| Stenostachys Turcz., 1862 |
| Stenotaphrum Trin., 1820 |
| Stenotaphrum americanum Schrank, 1822 |
| Stenotaphrum glabrum Trin., 1820 |
| Stenotaphrum glabrum var. americanum (Schrank) Döll, 1877 |
| Stenotaphrum glabrum var. glabrum Trin., 1820 |
| Stenotaphrum glabrum var. multiflorum Döll, 1877 |
| Stenotaphrum sarmentosum Nees, 1829 |
| Stenotaphrum secundatum (Walter) Kuntze, 1891 |
| Stephanostipa (Speg.) M.K. Elias, 1942 |
| Stephostachys Zuloaga & Morrone, 2010 |
| Stephostachys mertensii (Roth) Zuloaga & Morrone, 2010 |
| Stiburus Stapf, 1900 |
| Stilpnophleum Nevski, 1936 |