| 1 | Veins free. |
| 1' | Veins anastomosing, sometimes irregularly so and then some pinnules quite free-veined. |
| 2 | Pinnae in the basal part with segments only on the acroscopic side, in the apical part on both sides (Fig. 19); lamina pinnate + deeply pinnatifid |
| 2' | Pinnae equal-sided, or basiscopically more Compound than acroscopically; simply pinnate with entire pinnules, bipinnate, or more Compound. |
| 3 | Terminal segment of lateral pinnae narrow, acute, small in comparison to the pinnules next to it (Fig. 21); indusium not or scarcely erose, falling short of the margin by less than half its width |
| 3' | Terminal segment of lateral pinnae broad, rhombic, obtuse, or sometimes acuminate-caudate, large in comparison to the pinnules next to it; or lamina simply pinnate; indusium falling short of the margin by more than half its width (except often in L. javanensis). |
| 4 | Terminal segment of lateral pinnae (if any) as large as or often much larger than the basal pinnules of that pinna, rhombic to caudate-rhombic; no simply pinnate leaves with sharply dentate pinnules present beside the fertile ones; texture herbaceous to chartaceous; petiole dark, abaxially at least upward obtusely or usually acutely bi-angular |
| 4' | Terminal segment of lateral pinnae about as large as the larger basal pinnules of that pinna, flabellate, suborbiculate (Fig. 16); texture subcoriaceous to coriaceous; petiole dark, abaxially mostly rounded; sterile leaves with crenate pinnules often present. |
| 4'' | Terminal segment of lateral pinnae (if any) smaller than the larger basal pinnules of that pinna, rhombic, obtuse; texture herbaceous to chartaceous; petiole pale to dark, abaxially at least upward sharply bi-angular; unipinnate sterile leaves with sharply dentate pinnules often present |
| 5 | Larger secondary pinnules dimidiate, trapezoidal; pinnae without a large lanceolate undivided apical portion |
| 5' | Free secondary pinnules (if present) flabellate, not dimidiate; pinnae entire or with a large lanceolate undivided apical portion. |
| 6 | Veins even in larger pinnae (pinnules) irregularly anastomosing; upper (primary) free pinnules relatively wide, c. 1-3 times as long as wide |
| 6' | Veins regularly anastomosing, except in small secondary pinnules (if present); upper (primary) pinnules mostly relatively narrower |
