| 1 | Bases of pinnae, at least on their acroscopic side, cordate |
| 1' | Bases of pinnae hastate, their basal auricles acuminate |
| 2 | Pinnae of mature plants 10 cm or more long |
| 2' | Pinnae of mature plants c. 3.5 cm long |
| 3 | Few pairs of lower pinnae slightly reduced and more widely spaced; scales bearing marginal teeth |
| 3' | Many pairs of lower pinnae gradually much reduced; scales lacking marginal teeth |
| 4 | Sori exindusiate; acroscopic bases of middle pinnae not cordate |
| 4' | Sori indusiate; acroscopic bases of middle pinnae cordate |
