| Sophia millefolia Rydb., 1905 |
| Sophia myriophylla Rydb., 1901 |
| Sophia obtusa Greene, 1904 |
| Sophia ochroleuca Wooton, 1898 |
| Sophia pinnata (Walter) Howell, 1897 |
| Sphaerocardamum S. Schauer, 1847 |
| Sphaerocardamum compressum (Rollins) Rollins, 1984 |
| Sphaerocardamum divaricatum (Rollins) Rollins, 1984 |
| Sphaerocardamum fruticulosum (Rollins) Rollins, 1984 |
| Sphaerocardamum macropetalum (Rollins) Rollins, 1984 |
| Sphaerocardamum macrum (Standl.) Rollins, 1984 |
| Sphaerocardamum nesliiforme S. Schauer, 1847 |
| Sphaerocardamum ramosum Rollins, 1984 |
| Sphaerocardamum stellatum (S. Watson) Rollins, 1984 |
| Sphaerotorrhiza (O.E. Schulz) A.P. Khokhr., 1985 |
| Sprengeria Greene, 1906 |
| Sprengeria flava (Torr.) Greene, 1906 |
| Sprengeria minuscula Greene, 1906 |
| Sprengeria watsoniana Greene, 1906 |
| Stanfordia S. Watson, 1880 |