| 1 | Sori deeply sunken, visible as protrusions on the upper surface |
| 1' | Sori superficial or slightly immersed |
| 2 | Rhizome white waxy, with both sclerified circumvascular sheaths and scattered sclerenchyma strands, scales peltate |
| 2' | Rhizome not white waxy, with either scattered sclerenchyma strands or sclerified circumvascular sheaths, scales pseudopeltate |
| 3 | Apex of lobes rounded or acute, rhizome dorsiventrally flattened, rhizome with sclerified circumvascular sheaths, lamina herbaceous, lamina margin entire. |
| 3' | Apex of lobes long-acuminate, rhizome terete, with only scattered sclerenchyma strands, lamina membranaceous, lamina margin undulate. |
| 4 | Sori ± regularly spaced, either in a single (sometimes irregularly doubled) row between costa and margin, or in two rows between the lateral veins |
| 4' | Sori irregularly scattered over the lamina |
| 5 | Lamina pinnatifid, membranaceous |
| 5' | Lamina simple, herbaceous or subcoriaceous |
| 6 | Lamina elliptic, scales peltate, round or elliptic, often with eroded margins, sori on distinct soral veins |
| 6' | Lamina narrowly elliptic, ovate, obovate, or linear, scales pseudopeltate, (narrowly) ovate or triangular, margin usually intact, sori predominantly on connective veins |
| 7 | Roots densely set, rhizome terete, sclerenchyma strands 50-110, sori 1 (or 2) per veinlet |
| 7' | Roots sparsely set, rhizome dorsiventrally flattened, sclerenchyma strands 0-15, sori 2-4 per veinlet |
| 8 | Rhizome white waxy, with only scattered sclerenchyma strands. |
| 8' | Rhizome not white waxy, with sclerified circumvascular sheaths and scattered sclerenchyma strands, or not sclerified at all |
| 9 | Roots sparsely set, scales densely set |
| 9' | Roots densely set, scales apically densely set, elsewhere more sparsely set |
| 10 | Rhizome with circumvascular sheaths and scattered strands of sclerenchyma, sori on the whole surface of the lamina |
| 10' | Rhizome with only circumvascular sheaths, sori absent from the basal parts of the lamina |
| 11 | Scales in central region glabrous, margin entire or denticulate, phyllopodia more or less distinct, lamina thin-herbaceous, base narrowly angustate, decurrent to a long wing, connecting veins 1-3, between midrib and margin, mainly anadromous |
| 11' | Scales in central region bearing hairs at least when young, margin dentate, phyllopodia not elevated, lamina herbaceous, base truncate or cuneate, not long-decurrent, connecting veins 4-7 between midrib and margin, catadromous. |
