| Castilleja scorzonerifolia Kunth, 1818 |
| Castilleja sessiliflora Pursh, 1813 |
| Castilleja setosa Pennell, 1940 |
| Castilleja socorrensis Moran, 1989 |
| Castilleja speciosa M. Martens & Galeotti, 1845 |
| Castilleja sphaerostigma Eastw., 1909 |
| Castilleja spiranthoides Standl., 1936 |
| Castilleja stenantha A. Gray, 1878 |
| Castilleja stenophylla M.E. Jones, 1908 |
| Castilleja stipifolia G.L. Nesom, 1992 |
| Castilleja subalpina Eastw., 1909 |
| Castilleja tancitaroana G.L. Nesom, 1992 |
| Castilleja tapeinoclada Loes., 1903 |
| Castilleja tenuiflora Benth., 1839 |
| Castilleja tenuiflora var. tancitaroana (G.L. Nesom) J.M. Egger, 2008 |
| Castilleja tenuiflora var. tenuiflora Benth., 1839 |
| Castilleja tenuiflora var. xylorrhiza (Eastw.) G.L. Nesom, 1992 |
| Castilleja tenuifolia M. Martens & Galeotti, 1845 |
| Castilleja tenuifolia subsp. tenuifolia M. Martens & Galeotti, 1845 |
| Castilleja tolucensis Kunth, 1818 |