1All pinnae broadly adnate
1'At least the lower half of the frond fully pinnate, with articulate pinnae
2Rhizome scales with an appressed base, rhizome green, turning brown when dry.
2'Rhizome scales erect, rhizome glaucous or white-waxy beneath the scales.
3Venation 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
4Basal cells of rhizome scales not clathrate
4'Basal cells of rhizome scales clathrate
5Large 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)
6Sori deeply sunken
6'Sori superficial or slightly sunken
7Terminal 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
8Rhizome dorsiventrally flattened, in cross section with less than 20 sclerenchyma strands
8'Rhizome terete, in cross section with over 40 sclerenchyma strands
9Sori 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
10Sori 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.
11Sori superficial, small rhizome scales abundant
11'Sori slightly sunken, small rhizome scales not abundant
12Rhizome 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