| Wuerschmittia Schultz-Bip. ex Walp., 1846 |
| Wulffia Neck. ex Cass., 1823 |
| Wulffia angustifolia (A. Rich.) M. Gómez, 1890 |
| Wyethia Nutt., 1834 |
| Wyethia mexicana S. Watson, 1890 |
| Wyethia ovata Torr. & A. Gray, 1848 |
| Xanthidium Delpino, 1871 |
| Xanthidium ambrosioides (Cav.) Delpino, 1871 |
| Xanthisma DC., 1836 |
| Xanthisma arenarium (Benth.) D.R. Morgan & R.L. Hartm., 2003 |
| Xanthisma crutchfieldii (B.L. Turner) D.R. Morgan & R.L. Hartm., 2003 |
| Xanthisma gracile (Nutt.) D.R. Morgan & R.L. Hartm., 2003 |
| Xanthisma gymnocephalum (DC.) D.R. Morgan & R.L. Hartm., 2003 |
| Xanthisma gypsophilum (B.L. Turner) D.R. Morgan & R.L. Hartm., 2003 |
| Xanthisma johnstonii (S.F. Blake) D.R. Morgan & R.L. Hartm., 2003 |
| Xanthisma junceum (Greene) D.R. Morgan & R.L. Hartm., 2003 |
| Xanthisma pseudorestiforme B.L. Turner, 2010 |
| Xanthisma restiforme (B.L. Turner) D.R. Morgan & R.L. Hartm., 2003 |
| Xanthisma rhizomatum (M.C. Johnst.) D.R. Morgan & R.L. Hartm., 2003 |
| Xanthisma scabrellum (Greene) G.L. Nesom & B.L. Turner, 2007 |