| 1 | Stipe-scales flabelloid; hairs on lower surfaces, if present, crisped and appressed; pinnules in most cases deeply lobed, basal basiscopic vein rarely from costa; indusia in some cases hemitelioid. |
| 1' | Stipe-scales setiferous; hairs on lower surfaces, if present, rather thick and spreading; where pinnules are shallowly lobed, basiscopic vein always from costa; indusia complete, or lacking, or formed of separate scales (in a few cases imperfect, and then not hemitelioid). |
| 2 | Indusiate (indusia in some cases very small) or if exindusiate hairy on lower surface of pinna-rachis; axes not very dark; little dimorphism between sterile and fertile pinnules. Spp. 1-103. |
| 2' | Exindusiate; axes very dark, not hairy beneath; fertile and sterile pinnules usually very dimorphous. Spp. 104-120 |
| 3 | Costules not widely spaced (rarely over 4 mm apart in pinnules 10 cm long); pinnules usually 10 cm or more long, lobed almost or quite to costa throughout, or fully pinnate. Spp. 121-151. |
| 3' | Costules widely spaced (at least 4 mm apart except where pinnules are under 4 cm long); pinnules mostly less than 10 cm long, not lobed to within 1 mm of costa except near base; basal basiscopic vein always from costa; indusiate or not. Spp. 152-191 |
| 4 | Fre tertiary leaflets few; indusia present or absent; sori never covered with overlapping scales. Spp. 121-143 |
| 4' | Free tertiary leaflets many; no indusia; sori covered with overlapping scales. Spp. 144-151. |
| 5 | Scales of stipe 1 cell thick throughout. Spp. 152-178 |
| 5' | Scales of stipe thick and fleshy at base, tapering and flat distally (Fig. 30). Spp. 179-191. |
