| 1 | One pair of veins regularly anastomosing, at least near bases of larger pinnae; short hairs present between veins on upper surface. |
| 1' | Veins all free, or with casual slight anastomosis; upper surface between veins glabrous, or nearly so. |
| 2 | Sori exindusiate; pinnae less than 2 cm long |
| 2' | Sori indusiate; pinnae to 3 cm long |
| 3 | Pinnae to 1.3 cm long, almost entire; costules mostly forked, the branches of adjacent ones sometimes anastomosing |
| 3' | Pinnae (at least sterile ones) to 2 cm or more long, distinctly lobed at least on acroscopic side; veins all free. |
| 4 | Sterile pinnae to 2.5x1.0 cm, lobed equally both sides half-way to costa or more deeply, not conspicuously auricled; indusia setose |
| 4' | Sterile pinnae usually not over 2 cm long, 5-6 mm wide above the auricled base, lobed more deeply on acroscopic than on basiscopic side; indusia glandular |
