| 1 | Reduced pinnae present at base of stipe, separated from normal pinnae. |
| 1' | Reduced pinnae, separate from the rest, lacking; lower pinnae in some cases reduced gradually almost to base of stipe, the lowest sometimes with narrow segments. |
| 2 | Sterile pinnules of normal pinnae c. 40 by 10 mm, fertile c. 30 by 8 mm; veins 4 pairs. |
| 2' | Sterile pinnules of normal pinnae 60-100 by 15-20 mm, fertile 40-100 by 11-15 mm; veins 6-10 pairs. |
| 3 | Segments of reduced basal pinnae all with very narrow lamina, forming a wing along each side of the veins. |
| 3' | Segments of reduced basal pinnae all with broad lamina |
| 4 | Lower sori medial on veins, distal ones close to costule. Paraphyses slender at base, widening to scale-like apex |
| 4' | All sori close to costules. Paraphyses thick and dark at base, tapering to apex. |
| 5 | Fronds simply pinnate with entire pinnae (sterile) or bipinnate with few pinnae and almost entire sterile pinnules; in either case the true frond-apex short and abortive, evident above attachment of uppermost pinna. |
| 5' | Fronds with normal apex. |
| 6 | Fertile pinnules lobed almost or quite to costa |
| 6' | Fertile pinnules only slightly lobed |
| 7 | Pinnules almost entire. |
| 7' | Pinnules distinctly lobed. |
| 8 | Sterile pinnules to 50 by 10 mm, on stalks to 1 mm long; bullate scales present on costules. |
| 8' | Sterile pinnules to 120 by 20 mm, on stalks to 4 mm long; no bullate scales on costules. |
| 9 | Scales on lower surface of costules bullate. |
| 9' | Scales on lower surface of costules not bullate. |
| 10 | Bullate scales present on lower surface of veins of sterile pinnules. |
| 10' | Bullate scales lacking on veins. |
| 11 | Pinnules to 100 mm long with several pairs offree segments at base. |
| 11' | Pinnules to 65 mm long without free basal segments |
| 12 | Axes very dark; scales on lower surface of costae bearing many setae. |
| 12' | Axes not very dark; scales on lower surface of costae sometimes with a few setae. |
| 13 | Pinnules to 110 by 30 mm, cut to 2 mm from costae; costules of sterile pinnules to 6 mm apart. |
| 13' | Pinnules to 70 by 20 mm, cut to within 1 mm from costa; costules of sterile pinnules to 4.5 mm apart |
| 14 | Pinnules lobed almost to costa. |
| 14' | Pinnules not lobed more than ⅔ towards costa. |
| 15 | Costal scales not setiferous |
| 15' | Costal scales bearing many setae |
| 16 | Scales on costae bearing lateral setae. Segments or lobes of pinnules rounded and subentire. Sori usually not converging towards apices of segments. Basal basiscopic vein from costule. |
| 16' | Scales on costae lacking lateral setae. Segments of lamina deltoid and distinctly toothed. Sori converging towards apices of segments. Basal basiscopic vein often from costa. |
| 17 | Stipe and basal part of rachis persistently scaly; largest pinnules with stalks at most 2 mm; veins to 6 pairs |
| 17' | Persistent large scales only at base of stipe; largest pinnules with stalks to 4 mm; veins 3-5 pairs |
