| 1 | Fronds bearing many buds on rachis |
| 1' | Fronds lacking buds. |
| 2 | Veins free (in some cases basal veins of adjacent groups just meet at the sinus). |
| 2' | Veins anastomosing. |
| 3 | Sori elongate along veins. |
| 3' | Sori not elongate, or slightly so if without indusia (Abacopteris Fee, Haplodictyum Presl). |
| 4 | No indusia. |
| 4' | Indusia present |
| 5 | Venation as in Cyclosorus; veins from adjacent costules uniting to form a single excurrent vein. |
| 5' | Venation irregularly anastomosing, often with additional enclosed areoles. |
