| 1 | Inner petals distinctly bifid. |
| 1' | Inner petals entire, usually lanceolate. |
| 2 | Leaves 1.5-2(-2.5) times as long as wide; petiole ¼-⅔ as long as the blade. Panicles 5-15 cm. Mature buds 2-2.5 mm diam. Endocarps ellipsoid to obovoid |
| 2' | Leaves (1.6—)2—3 times as long as wide; petiole (l/6-)l/5-l/3 (-½) as long as the blade. Panicles 3-30 cm. Mature buds 1.5-2(-2.2) mm diam. Endocarps long- to short-ellipsoid (always distinctly higher than wide) |
| 3 | Inner petals 2.5 mm. Panicles distinctly axillary or ramiflorous. Mature buds 2.5-3 mm diam. |
| 3' | Inner petals 1-1.5 mm. Panicles terminal or crowded at the end of the twigs, rarely distinctly axillary. Mature buds 2-2.5 mm diam. |
