| 1 | Fertile pinnae similar to sterile pinnae |
| 1' | Fertile pinnae distinctly contracted |
| 2 | Sori elliptic, in a single row between the veins, one in each main areole; rhizome scales without thickened midrib |
| 2' | Sori round, in many irregular rows between the veins, many in each main areole, rhizome scales with thickened midrib |
| 3 | Fronds pinnate, pinnae shortly stalked, nectaries on small appendages at the pinna bases |
| 3' | Fronds lobed to pinnatifid, pinnae sessile, nectaries on the lamina |
| 4 | At least fertile fronds stalked, without dilated base, rhizome scales appressed |
| 4' | All fronds sessile, with a dilated base, rhizome scales spreading or squarrose |
| 5 | Sterile sessile fronds present. |
| 5' | Sterile fronds, if present, stalked |
| 6 | Fertile fronds completely fertile, sori round, in several rows between costa and margin, rhizome scales peltate |
| 6' | Fertile fronds at the base sterile, sori on narrowed apical parts, quadrangular or elongated, in a single row between costa and margin, rhizome scales pseudopel-tate |
| 7 | Sori mostly forming a continuous coenosorus, but rarely interrupted. |
| 7' | Sori quadrangular or elongated, not a continuous coenosorus |
| 8 | Sporangia glabrous |
| 8' | Sporangia with 1-6 hairs |
| 9 | Fertile pinnae between the sori distinctly contracted to a narrow inconspicuous wing |
| 9' | Fertile pinnae not contracted between the sori |
| 10 | Rhizome not fully covered by the scales, with conspicuous phyllopods, fronds more than 20 cm distant |
| 10' | Rhizome completely covered with scales, phyllopods inconspicuous, fronds less than 10 cm apart |
| 11 | Sori linear, coenosoroid, rhizome scales without thickened midrib. |
| 11' | Sori separate, rhizome scales with a thickened midrib |
| 12 | Rhizome long-creeping, fronds over 20 cm distant, the midrib of rhizome scales black, sori round |
| 12' | Rhizome short-creeping, fronds less than 10 cm apart, midrib of rhizome scales brown |
| 13 | Sori in several rows, confluent into irregularly quadrangular patches, abscission vein glabrous |
| 13' | Sori forming a single row of regular, quadrangular, large patches, abscission vein with short hairs |
