| 1. | Leaves bullate or undulate | 2 |
| 1. | Leaves smooth | 4 |
| |
| 2. | Leaves 1 - 4 cm broad, bullate | var. balansae |
| 2. | Leaves narrower, 0.2 - 1.2 cm broad, undulate | 3 |
| |
| 3. | Leaves 0.2 - 0.4 cm broad | var. tonkinensis |
| 3. | Leaves 0.6 - 1.2 cm broad | var. flaccidifolia |
| |
| 4. | Leaves rather stiff, 10 - 15 (-20) cm long, 0.8 - 1.5 cm broad | var. sinensis |
| 4. | Leaves longer and/or narrower | 5 |
| |
| 5. | Leaves very narrow, 0.2 - 0.4 cm broad, 20 (-30) cm long, very flaccid | var. tonkinensis |
| 5. | Leaves 0.6 - 1.2 cm broad, 15 - 50 cm long, rather stiff or flaccid | 6 |
| |
| 6. | Leaves rather stiff, 15 - 40 cm long, margin smooth or denticulate | var. crispatula |
| 6. | Leaves flaccid, 20 - 50 cm long, margin smooth | var. flaccidifolia |