| 1 | Pinna-rachis hairy on the lower surface. |
| 1' | Pinna-rachis not hairy on lower surface. |
| 2 | Scales on costae setiferous. |
| 2' | Scales on costae not setiferous |
| 3 | Few or no bullate scales. Pinnules lobed to 2 mm from costa |
| 3' | Bullate scales present. Pinnules lobed to within 1 mm from costa |
| 4 | Indusium quite lacking. |
| 4' | Indusium present. |
| 5 | Pinnules almost sessile, to 28 mm wide |
| 5' | Pinnules long-stalked, to 45 mm wide |
| 6 | Pinnules on stalks to 6 mm long. Stipe to 60 cm |
| 6' | Pinnules sessile or on much shorter stalks. Stipe much shorter. |
| 7 | Pinnules to 35 mm wide, larger ones with lowest 1-2 lamina-segments free. No bullate scales. |
| 7' | Pinnules rarely over 25 mm wide, lowest segments not free. Bullate scales usually present on eostules. |
| 8 | Pinnules lobed only in basal half |
| 8' | Pinnules deeply lobed throughout. |
| 9 | Pinnules not over 20 mm wide, lobed to c. 3 mm from costa |
| 9' | Pinnules on largest pinnae in most cases over 20 mm wide, lobed to 1-2 mm from costa. |
| 10 | Scales on costae and costules bullate, mostly entire |
| 10' | Scales on costae mostly small and fringed or setiferous; bullate scales on costae and costules mostly fringed. |
| 11 | Pinnules of largest pinnae 22-28 mm wide. |
| 11' | Pinnules of largest pinnae less than 20 mm wide |
| 12 | Segments of lamina narrowed rather evenly from base to pointed apex, sinuses thus triangular. Scales on eostae not setiferous; bullate scales few. Lowest pinnae not greatly reduced. |
| 12' | Segments of lamina with rounded apex. Scales on costae often setiferous, bullate scales usually present. Lowest pinnae small, stipe very short |
