| Name | From | To | Age range |
|---|---|---|---|
| Alnus scotica | Late Paleocene | Early Miocene |
|
| Alnus scotia | Late Paleocene | Early Eocene |
|
| Alnus rugosa | Tertiary | Early Pleistocene |
|
| Alnus rubriformis | Paleocene | Early Pliocene |
|
| Alnus rubra | Paleogene | Neogene |
|
| Alnus rhombifolia | Paleogene | Neogene |
|
| Alnus recollecta | Paleogene | Neogene |
|
| Alnus raris | Late Pliocene | Late Pliocene |
|
| Alnus quinquepollenites | Late Cretaceous | Early Pliocene |
|
| Alnus quaternaria | Late Cretaceous | Late Cretaceous |
|
| Alnus quadropollenites | Eocene | Priabonian |
|
| Alnus quadriangula | Early Oligocene | Early Oligocene |
|
| Alnus quadrapollenites | Late Cretaceous | Early Pliocene |
|
| Alnus quadrangula | Middle Pliocene | Middle Pliocene |
|
| Alnus ptolemais | Late Neogene | Late Neogene |
|
| Alnus principalis | Paleogene | Neogene |
|
| Alnus precordata | Late Eocene | Late Eocene |
|