| 1 | Sori in cups at ends of veins. |
| 1' | Sori at ends of veins, variously protected, not in cups. |
| 2 | Rhizome slender, creeping, hairy |
| 2' | Rhizome stout, erect, scaly |
| 3 | Sori lacking protection; glandular hairs mixed with sporangia |
| 3' | Sori with indusium or covered when young by reflexed lobe of edge of lamina; no glandular hairs with sporangia. |
| 4 | Sori distinctly superficial, each at the end of a single vein and protected by an indusium which is pocket-shaped (attached by base and sides), opening towards margin. |
| 4' | Sori more or less protected by reflexed edge (or lobes of edge) of lamina, with or without an inner indusium also. |
| 5 | Sori almost continuous along edges of lamina. |
| 5' | Sori singly at ends of veins, or uniting a few veins, not continuous along all edges of lamina. |
| 6 | Veins anastomosing; no inner indusium |
| 6' | Veins free; inner indusium present |
| 7 | No inner indusium |
| 7' | Inner indusium present |
