| 1 | Sori in a single (sometimes irregularly doubled) row between costa and margin or between each pair of veins |
| 1' | Sori scattered on the lamina surface |
| 2 | Lamina simple |
| 2' | Lamina pinnatifid |
| 3 | Rhizome white waxy, scales (narrowly) ovate or triangular, sori deeply sunken, visible as protrusions on the upper surface |
| 3' | Rhizome not white waxy, scales round or elliptic, often with eroded margins, sori superficial or slightly immersed |
| 4 | Lamina elliptic, base cuneate-angustate, scales 0.8-1.2 mm long. |
| 4' | Lamina linear, base narrowly angustate, decurrent into a long wing, scales 1.5-2.5 mm long |
| 5 | Rhizome white waxy, rhizome with both sclerified circumvascular sheaths and scattered sclerenchyma strands |
| 5' | Rhizome not white waxy, with scattered sclerenchyma strands or with sclerified circumvascular sheaths |
| 6 | Sori in several rows between costa and margin, scales peltate. |
| 6' | Sori more or less in one row parallel to the costa, scales pseudopeltate |
| 7 | Apex of lobes rounded or acute, lamina margin entire, rhizome dorsiventrally flattened, with sclerified circumvascular sheaths, lamina herbaceous. |
| 7' | Apex of lobes long-acuminate, lamina margin undulate, rhizome terete, with scat-tered sclerenchyma strands, lamina membranaceous. |
| 8 | Scales round or elliptic, often with eroded margins, sori predominantly on veinlets, or on distinct soral veins |
| 8' | Scales (narrowly) ovate or triangular, the margins normally intact, sori mostly irregularly scattered on the smallest veinlets or predominantly on connecting veins |
| 9 | Connecting veins forming one row of large areoles parallel to the costa, bordered by several smaller areoles |
| 9' | Connecting veins forming several equally sized areoles between two adjacent veins, sometimes the first connecting vein forming one row of small primary costal areoles |
| 10 | Rhizome without sclerenchyma, sori generally absent from costal areoles. |
| 10' | Rhizome with sclerified circumvascular sheaths, sori generally present in costal areoles |
| 11 | Rhizome white waxy, without sclerified circumvascular sheaths. |
| 11' | Rhizome not white waxy, with sclerified circumvascular sheaths |
| 12 | Rhizome with circumvascular sclerified sheaths and strands of sclerenchyma. |
| 12' | Rhizome with only circumvascular sheaths |
| 13 | Sclerenchyma strands 50-100 |
| 13' | Sclerenchyma strands 0-15 |
| 14 | Veins zigzag, roots sparsely set, scales densely set, lamina herbaceous or subcoriaceous, sori predominantly on connective veins |
| 14' | Veins more or less straight, roots densely set, scales apically densely set, elsewhere more sparsely set, lamina thin-herbaceous, sori mostly irregularly scattered on the ultimate veinlets |
| 15 | Roots sparsely set, scales densely set |
| 15' | Roots densely set, scales apically densely set, elsewhere more sparsely set |
| 16 | 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 |
| 16' | Scales in central region bearing hairs at least when young, margin dentate, phyllopodia not elevated, lamina herbaceous, base truncate or cuneate, connecting veins 4-7 between midrib and margin, catadromous |
