| 1 | Fronds simply pinnate, pinnae entire or at most serrate-crenate. |
| 1' | Fronds simply pinnate with deeply lobed pinnae, or bipinnate. |
| 2 | Apex of frond a deltoid deeply lobed lamina. Outer veins of each group joining to form a single excurrent vein. Pinnae sessile, base truncate or subcordate |
| 2' | Apex of frond a pinna of same shape as other pinnae. No anastomosis. Pinnae usually stalked. |
| 3 | Pinnae not over 15 mm wide, base narrowly cuneate, stalkes to 12 mm long. Sori in 1-2 rows on each side of costa, fully indusiate |
| 3' | Pinnae 2-4 cm wide, base rather broadly cuneate, stalked or not. Sori in fully fertile fronds in more than 2 rows, indusiate or not. |
| 4 | Pinnae not long-acuminate, upper usually sessile |
| 4' | Pinnae long-acuminate, all stalked |
| 5 | Fronds simply pinnate with deeply lobed pinnae, the largest sometimes with free pinnules at their base. |
| 5' | Fronds amply bipinnate. |
| 6 | Lower surface of pinna-midribs covered near base with long hairs; no free pinnules. |
| 6' | Lower surface of pinna-midrib lacking hairs; some free pinnules on largest pinnae. |
| 7 | Indusium present (sometimes hidden by mature sorus). |
| 7' | Indusium lacking. |
| 8 | Lower pinnae little narrowed at base, free leaflets as long as lobes, apex not long-acuminate; pinnae commonly 25 cm long |
| 8' | Lower pinnae narrowed to base so that free leaflets are very small, apex long-acuminate; pinnae to 18 cm long |
| 9 | Pinnae commonly 25 cm long; no long pale hairs on rachis |
| 9' | Pinnae much shorter; main rachis bearing long pale hairs |
| 10 | Pinnules entire or with crenate edges. |
| 10' | Pinnules distinctly lobed. |
| 11 | Indusia present; pinnules sessile |
| 11' | Indusia lacking; pinnules stalked |
| 12 | Sori indusiate. |
| 12' | Sori without indusia. |
| 13 | Pinnules of larger pinnae not lobed more than ¾ to costa throughout, no free basal segments, or sometimes one on lowest pinnule of lower pinnae. |
| 13' | Pinnules of larger pinnae always with one or more free basal segments. |
| 14 | Bullate scales lacking on costules |
| 14' | Bullate scales present on costules. |
| 15 | Basal pinnules of middle pinnae with stalks to at least 4 mm long; pinnules lobed less than ½ way to costa |
| 15' | Basal pinnules sessile or nearly so; pinnules lobed more than half way to costa. |
| 16 | Segments of pinnules acute, falcate; largest pinnules 20-30 mm wide. |
| 16' | Segments of pinnules rounded; largest pinnules not over 20 mm wide. |
| 17 | Indusium a disc hidden by sorus |
| 17' | Indusium complete, breaking and persistent at maturity. |
| 18 | Lower surface of costae densely scaly |
| 18' | Lower surface of costae not densely scaly |
| 19 | Copious long hairs on lower surface of veins as well as costules. |
| 19' | No hairs on lower surface of veins. |
| 20 | About half the tertiary segments free or separately adnate to costa on largest pinnules. Pinnules to 100 by 20 mm. Costae not densely scaly |
| 20' | One or two pairs tertiary segments free on largest pinnules. Pinnules to 80 by 12 mm. Costae densely scaly. |
| 21 | Costal scales not setiferous. Pinnules sessile |
| 21' | Costal scales strongly setiferous. Lower pinnules with stalks 2-3 mm long. |
| 22 | Free basal segments of largest pinnules deeply lobed. Rachis and pinna-rachis densely persistently scaly, scales small, sub-bullate, setiferous |
| 22' | Free basal segments entire. Rachises glabrescent. |
| 23 | Pinnules sessile, to c. 65 by 15 mm, often smaller |
| 23' | Pinnules stalked (stalks to 8 mm), to 100 by 25 mm |
| 24 | Long-spreading hairs abundant on lower surface of rachis and/or pinna-rachis, often also on costae. |
| 24' | Long spreading hairs lacking on lower surface of rachis and pinna-rachis. |
| 25 | Costules and veins bearing hairs like those of costae on lower surface. |
| 25' | Costules and veins lacking hairs on lower surface. |
| 26 | Pinnules to 110 mm long, cut to costa; costules 5 mm apart. |
| 26' | Pinnules to 65 mm long, cut to within 1 mm of costa; costules 3-3l/2 mm apart. |
| 27 | Hairs of lower surface confined, or almost confined, to main rachis. |
| 27' | Hairs of lower surface present on pinna-rachis and costae, few or none on main rachis. |
| 28 | Largest pinnules with a free segment at the base; pinnules on stalks to 4 mm or more long; texture firm |
| 28' | Largest pinnules lacking a free segment at the base, almost sessile. |
| 29 | Sori on 3-4 pairs of basal veins in each group only, not on distal veins, at maturity confluent. |
| 29' | Sori on almost all veins, not confluent at maturity. |
| 30 | Bullate scales lacking on costae and costules. Pinnules cut to less than 1 mm from costa; stout erect hairs abundant on upper surface of costules and veins. |
| 30' | Bullate scales present on costae and costules. Pinnules less deeply lobed; hairs on upper surface of costules few |
