| 1 | Plants small (dwarfed) and/or fronds simple. |
| 1' | Plants not dwarfed. Fronds pinnate. |
| 2 | Bulbil ± terminal. Pinnae 16-30 |
| 2' | Bulbils subterminal (or absent). Pinnae less. |
| 3 | Veins irregularly anastomosing, usually with many ex- and recurrent free veins. Fronds entire or (bi)trifid |
| 3' | Veins regularly anastomosing, without free veins or with few ex- and recurrent free veins. Fronds entire. |
| 4 | Fronds coriaceous. |
| 4' | Fronds herbaceous (to subcoriaceous). |
| 5 | Areoles (except the costal one) all of about the same shape, decreasing in size towards the margin |
| 5' | Areoles of different size and shape, not decreasing in size towards the margin. |
| 6 | Fronds pinnate. Venation of terminal segment as in Fig. 31j, k |
| 6' | Fronds entire or if pinnate with a venation as in Fig. 31g or simpler. |
| 7 | Veins free. |
| 7' | Veins anastomosing. |
| 8 | Bulbil ± terminal on the lamina. Spines on the margin of the pinnae ± flattened at their bases. Base of pinnae symmetrical |
| 8' | Bulbil subterminal on the lamina. Spines on the margin not flattened at their bases. Base of pinnae symmetrical or asymmetrical. |
| 9 | Perispore smooth. Base of pinnae symmetrical, margin lobed 1/3-⅔(-¾) towards the costa |
| 9' | Perispore reticulate. Base of pinnae either symmetrical or asymmetrical; if symmetrical, margin of the pinnae entire or lobed to ⅓(-1/2) towards the costa |
| 10 | Fronds ± coriaceous. |
| 10' | Fronds herbaceous. |
| 11 | Terminal segment conform to the pinnae, though usually larger |
| 11' | Terminal segment triangular |
| 12 | Fronds drying reddish. Perispore undulate |
| 12' | Fronds drying greenish. Perispore undulate, cristate-undulate, or cristate. |
| 13 | Terminal segment conform to the pinnae or composed of 2 or 3 lobes. |
| 13' | Terminal segment triangular. |
| 14 | Venation pattern with many excurrent included free veins. |
| 14' | Venation pattern without or with only few excurrent (and recurrent) included free veins. |
| 15 | Perispore undulate. |
| 15' | Perispore cristate |
| 16 | Pinnae 2-10(-15) to a frond |
| 16' | Pinnae more than 15 to a leaf |
| 17 | Bulbil ± terminal. Small plant |
| 17' | Bulbil subterminal. |
| 18 | Terminal segment narrowly triangular. Perispore undulate |
| 18' | Terminal segment triangular. Perispore cristate or cristate-undulate. |
| 19 | Venation pattern irregular. See Fig. 27i |
| 19' | Venation pattern regular. |
| 20 | Base of pinnae narrow-acute or -cuneate. Pinnae 7.5-12 by 1-1¾ cm |
| 20' | Base of pinnae wider. Pinnae usually larger |
