| Streptanthus longirostris (S. Watson) S. Watson, 1890 |
| Streptanthus micranthus A. Gray, 1849 |
| Streptanthus platycarpus A. Gray, 1853 |
| Streptanthus simulans (Payson) Jeps., 1924 |
| Streptanthus validus (Greene) Cory, 1936 |
| Stroganowia Kar. & Kir., 1841 |
| Strophades Boiss., 1842 |
| Stubendorffia Schrenk, 1844 |
| Stylocarpum Noulet, 1837 |
| Stylonema (DC.) Kuntze, 1891 |
| Synthlipsis A. Gray, 1849 |
| Synthlipsis berlandieri A. Gray, 1858 |
| Synthlipsis densiflora Rollins, 1959 |
| Synthlipsis elata Rollins, 1959 |
| Synthlipsis greggii A. Gray, 1849 |
| Synthlipsis greggii var. greggii A. Gray, 1849 |
| Synthlipsis greggii var. hispidula Rollins, 1939 |
| Synthlipsis heterochroma S. Watson, 1882 |
| Syrenia Andrz. ex Besser., 1822 |
| Syreniopsis H.P. Fuchs, 1959 |