| 1 | Veins in pinnae less than 10 pairs, or if more than 10, sori indusiate; yellow spherical glands often present, at least on sporangia |
| 1' | Veins in pinnae 10 pairs or more, or if fewer, excurrent veinlets all free; sori exindusiate; spherical glands never present |
| 2 | Apical lamina pinna-like or much larger than pinnae; pinnae not auricled on acroscopic base; fronds of young plants simple, in P. beccarianum all fronds simple |
| 2' | Apical lamina not pinna-like, or if so pinnae auricled on acroscopic base; fronds of young plants rarely simple |
| 3 | No hooked hairs on any part of plant; sori rarely coalescent |
| 3' | Hooked hairs present on sporangia or on some other part of plant; sori often elongate or coalescent |
