Northern Prairie Wildlife Research Center
A large fern family of which several taxa grow in swampy or boggy places.
| Lead | Characteristic | Go To |
| 1 | Fertile fronds brown, structurally unlike the green sterile fronds. | Lead 2 |
| 1 | Fertile and sterile fronds green, structurally similar. | Lead 3 |
| 2 | Sterile fronds pinnate at the base, pinnatifid upward; veins of the pinnae anastomosing. | Genus Onoclea (O. sensibilis) |
| 2 | Sterile fronds pinnate-pinnatifid; veins of the pinnae free. | Genus Matteuccia (M. struthiopteris) |
| 3 | Ultimate leaf segments mostly flabellate; sori borne beneath reflexed margins of the lobes on the leaf segments. | Genus Adiantum (A. capillus-veneris) |
| 3 | Ultimate leaf segments not flabellate; sori borne on the underside of the leaf segments. | Lead 4 |
| 4 | Indusium attached at its center in the middle of the sorus. | Lead 5 |
| 4 | Indusium attached along its margin to one side of the sorus. | Genus Athyrium (A. filix-femina) |
| 5 | Fronds pubescent, especially on the rachis and midnerves of the pinnae; petioles without scales. | Genus Thelypteris (T. palustris) |
| 5 | Fronds glabrous; petioles with membranous scales. | Genus Dryopteris |