| 1 | Teeth present at the bases of sinuses between pinna- or pinnule-lobes, the teeth projecting out of the plane of the lamina |
| 1' | Teeth of this kind lacking |
| 2 | Fronds simply pinnate with free veins; no unicellular glands on lamina or in sori |
| 2' | Fronds mostly bipinnate, their veins forming at least costal aréoles; cylindric glands present |
| 3 | All axes of the frond bearing copious scales, the smaller ones at least partly clathrate with isodiametric cells |
| 3' | Smaller axes of the frond bearing few scales which are not thus clathrate |
| 4 | Veins in sterile fronds anastomosing copiously; free veinlets in areoles (including those along costae) variously directed and in most species forked |
| 4' | Veins anastomosing to form costal areoles which lack free veinlets, or all veins free |
| 5 | Fertile fronds greatly contracted and bearing indusia |
| 5' | Fertile fronds not greatly contracted, or if so lacking indusia |
| 6 | Sterile fronds simple; fertile ones irregularly deeply lobed; indusia reniform |
| 6' | Sterile fronds pinnate; pinnae of fertile fronds linear, with continuous indusia along each side of the costae |
| 7 | Some thick multicellular hairs present between veins on the upper surface, at least near sinuses between lobes |
| 7' | No thick hairs present between veins on upper surface |
| 8 | Basal basiscopic lobe or pinnule of basal pinnae longer than the other lobes or pinnules |
| 8' | Basal basiscopic lobe of basal pinnae much reduced, these pinnae widest at about mid-length |
| 9 | Fronds not greatly longer than wide |
| 9' | Fronds greatly longer than wide, with many pinnae gradually increasing in size downwards |
| 10 | Veins anastomosing in some species; fertile fronds, if greatly contracted, not bearing very small pinnules |
| 10' | Veins all free; fertile fronds bipinnate with very small pinnules, exindusiate |
| 11 | Pinnae articulate to the rachis, entire or crenate |
| 11' | Pinnae not articulate, deeply lobed or pinnate |
