| Odontotrichum napellifolium (S. Schauer) Rydb., 1924 |
| Odontotrichum nephrophyllum Rydb., 1924 |
| Odontotrichum pachyphyllum (Sch. Bip.) Rydb., 1924 |
| Odontotrichum palmeri (Greene) Rydb., 1924 |
| Odontotrichum paucicapitatum (B.L. Rob. & Greenm.) Rydb., 1924 |
| Odontotrichum platylepis (B.L. Rob. & Seaton) Rydb., 1924 |
| Odontotrichum pratense (Standl.) Cuatrec., 1955 |
| Odontotrichum pringlei (S. Watson) Rydb., 1924 |
| Odontotrichum purpusii (Greenm.) Rydb., 1924 |
| Odontotrichum radulifolium (Kunth) Rydb., 1924 |
| Odontotrichum scabrum Rydb., 1924 |
| Odontotrichum schaffneri (A. Gray) Rydb., 1924 |
| Odontotrichum silphiifolium (B.L. Rob. & Greenm.) Rydb., 1924 |
| Odontotrichum sinuatum (Cerv.) Rydb., 1924 |
| Odontotrichum tridactylitis (B.L. Rob. & Greenm.) Rydb., 1924 |
| Odontotrichum tussilaginoides (Kunth) Rydb., 1924 |
| Oedera L., 1771 |
| Oedera trinervia Spreng., 1800 |
| Ogiera Cass., 1818 |
| Oglifa (Cass.) Cass., 1822 |