| 1 | Fertile parts strongly contracted |
| 1' | Fertile parts similar to sterile part or narrowed |
| 2 | Sori in two rows between adjacent veins |
| 2' | Sori in one row between adjacent veins or forming coenosori |
| 3 | Hydathodes absent or sparse |
| 3' | Hydathodes frequent |
| 4 | Sori round or elongate |
| 4' | Sori confluent or forming coenosori |
| 5 | Rhizome scales entire, ground tissue with subperipheral sclerified sheath. |
| 5' | Rhizome scales short-dentate to long-ciliate, ground tissue not sclerified |
| 6 | Margin of fronds with notches regularly present, rhizome scales strongly dentate or ciliate, fertile fronds as long as or longer than sterile ones. |
| 6' | Margin of fronds without notches or notches sporadically present, rhizome scales short-dentate, fertile fronds usually shorter than sterile ones |
| 7 | Sori confluent across veins, forming longitudinal coenosori |
| 7' | Sori confluent across connecting veins only, forming transverse coenosori. |
| 8 | Rhizome radial (in part), sterile fronds narrow, index 6-18, sclerenchyma strands in the rhizome absent to many |
| 8' | Rhizome completely dorsiventral, sterile fronds wider, index 2-7, sclerenchyma strands in the rhizome very many |
| 9 | Rhizome not sclerified, rhizome scales narrow, 1-1.5 mm wide, remotely and weakly to strongly dentate |
| 9' | Rhizome with subperipheral sclerified sheath, rhizome scales broad, 1.8-3 mm wide, with a flabelloid, irregular margin |
| 10 | Fertile fronds to c. 1.4 cm wide, index c. 10, rhizome scales densely set, covering the glaucous rhizome |
| 10' | Fertile fronds to c. 1 cm wide, index 13-14, rhizome scales sparsely set, not fully covering the glaucous rhizome |
| 11 | Sori in two or more rows between adjacent veins (or indistinct) |
| 11' | Sori in one row between adjacent veins |
| 12 | Lamina thickly coriaceous, margin cartilaginous, very strongly thickened. |
| 12' | Lamina chartaceous to coriaceous, margin not differentiated, flat, or thicken- ed |
| 13 | Fertile fronds widest above middle, midrib with two sharply distinct, raised ridges on upper surface |
| 13' | Fertile fronds widest below middle or gramineous, midrib flat or with shallow ridges on upper surface |
| 14 | Fronds pinnate |
| 14' | Fronds simple |
| 15 | Hydathodes with persistent calcareous scales, rhizome scales peltate, strongly dentate or long-ciliate, margin of fronds without notches. |
| 15' | Hydathodes without persistent calcareous scales, rhizome scales pseudopeltate, entire or shortly dentate, margin of fronds regularly notched. |
| 16 | Rhizome scales obtuse |
| 16' | Rhizome scales acute or contracted to a narrow acumen |
| 17 | Rhizome scales densely set, overlapping, covering the rhizome, apex flat. |
| 17' | Rhizome scales sparsely set, not overlapping, not covering the rhizome, apex often cucullate |
| 18 | Sori sunken |
| 18' | Sori superficial or slightly sunken |
| 19 | Sori in transverse coenosori, veins distinct |
| 19' | Sori round, costa only distinct |
| 20 | Hydathodes absent, rhizome scales with subulate acumen |
| 20' | Hydathodes frequent, rhizome scales with acumen not subulate. |
| 21 | Rhizome scales contracted to a narrow acumen, with a lighter margin |
| 21' | Rhizome scales acute, often with irregular dark spots |
| 22 | Fertile fronds to c. 1.4 cm wide, index c. 10, rhizome scales densely set, covering the glaucous rhizome |
| 22' | Fertile fronds to c. 1 cm wide, index 13-14, rhizome scales sparsely set, not fully covering the glaucous rhizome |
| 23 | Sori 4-5 mm wide, lamina often with some persistent scales |
| 23' | Sori 3-4 mm wide, lamina glabrous |
