| 1 | All pinnae broadly adnate |
| 1' | At least the lower half of the frond fully pinnate, with articulate pinnae |
| 2 | Rhizome scales with an appressed base, rhizome green, turning brown when dry. |
| 2' | Rhizome scales erect, rhizome glaucous or white-waxy beneath the scales. |
| 3 | Venation with a single row of areoles, a second irregular row composed of scattered areoles without included veinlets sometimes present |
| 3' | Venation with 2 or 3 rows of areoles, at least 2 rows with included veinlets |
| 4 | Basal cells of rhizome scales not clathrate |
| 4' | Basal cells of rhizome scales clathrate |
| 5 | Large plants; stipe 3-5 mm thick at the base, lamina over 40 cm, widest above the base, rhizome scales gradually contracted into a wide, strongly dentate acumen (20 or more cells wide at the base) |
| 5' | Small plants; stipe less than 2 mm thick at the base, lamina less than 20 cm long, widest at the base, rhizome scales rather suddenly contracted into a narrow, shortly dentate acumen (12 cells wide or less) |
| 6 | Sori deeply sunken |
| 6' | Sori superficial or slightly sunken |
| 7 | Terminal segment 2/3 as long as or longer than longest lateral pinna, vascular strands without dark sheaths |
| 7' | Terminal segment about half as long as longest lateral pinna, vascular strands with dark sheaths |
| 8 | Rhizome dorsiventrally flattened, in cross section with less than 20 sclerenchyma strands |
| 8' | Rhizome terete, in cross section with over 40 sclerenchyma strands |
| 9 | Sori uni- to triserial, lamina less than 1.2 as long as wide, spores with very long polar excrescences |
| 9' | Sori uniserial, lamina 1.5 as long as wide or longer, spores with short polar excrescences |
| 10 | Sori small, less than 1 mm wide, deeply sunken, surrounded by a ring of dark paraphyses |
| 10' | Sori larger, c. 2 mm wide, slightly sunken, without ring of dark paraphyses. |
| 11 | Sori superficial, small rhizome scales abundant |
| 11' | Sori slightly sunken, small rhizome scales not abundant |
| 12 | Rhizome scales dull dark brown, with a relatively wide acumen, apex not filiform, superficial hairs absent; fronds dark green with firm stipe and rachis (living plants), rhizome with many (30-50) sclerenchyma strands, sori 1.5-2 mm wide, sporangia sometimes bearing acicular hairs |
| 12' | Rhizome scales light brown, with a narrow acumen and filiform apex, often with superficial hairs; fronds light green with very flexible stipe and rachis (living plants), rhizome with very many (100 or more) sclerenchyma strands, sori 1-1.5 mm wide, sporangia glabrous |
