| 1 | Sporangia in two rows, embedded in an almost terete spike. |
| 1' | Sporangia on branches of the fertile segment of a frond. |
| 2 | Fertile segment of frond compact, with many short branches; sterile segment tripartite, each part with few leaflets |
| 2' | Fertile segment of frond amply branched with spreading branches; sterile segment (in Malaysian species) pinnately branched with many small divisions |
