1 | Fertile fronds isomorphous with sterile ones, or nearly so, their lower surface glabrous be tween veins |
1' | Fertile fronds much contracted, their lower surface bearing many hairs between veins |
2 | Indusia distinct on all sori |
2' | Indusia very small, hidden by sporangia, or lacking |
3 | Costae densely short-hairy on upper surface |
3' | Costae glabrous on upper surface |