| Alnus Mill., 1754 |
| Alnus acuminata Kunth, 1817 |
| Alnus acuminata subsp. acuminata Kunth, 1817 |
| Alnus acuminata subsp. arguta (Schltdl.) Furlow, 1977 |
| Alnus acuminata subsp. glabrata (Fernald) Furlow, 1977 |
| Alnus arguta (Schltdl.) Spach, 1841 |
| Alnus arguta var. cuprea Bartlett, 1909 |
| Alnus ferruginea Kunth, 1817 |
| Alnus firmifolia Fernald, 1907 |
| Alnus glabrata Fernald, 1904 |
| Alnus guatemalensis Gand., 1920 |
| Alnus jorullensis Kunth, 1817 |
| Alnus jorullensis subsp. jorullensis Kunth, 1817 |
| Alnus jorullensis subsp. lutea Furlow, 1977 |
| Alnus oblongifolia Torr., 1859 |
| Alnus ovalifolia Bartlett, 1909 |
| Alnus pringlei Fernald, 1907 |
| Alnus rhombifolia Nutt., 1842 |
| Betula L., 1753 |
| Betula arguta Schltdl., 1832 |