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| 1 Woody vine, climbing by axillary tendrils; leaves 2-foliolate |
| 1 Tree; leaves simple, 2-lobed. |
| ..2 Stems with stipular spines at or near the nodes; stamens 10; corolla white |
| ..2 Stems lacking spines; stamens 3 or 5; corolla white, pink, or purple. |
| ....3 Functional stamens 3; petals ca. 1.5 (-2) cm wide, not overlapping; flower buds clavate and also slightly winged towards the tip; spathiform calyx splitting along 2 lines |
| ....3 Functional stamens 5; petals 1.5-3 cm wide, overlapping; flower buds spindle-shaped, tapering to the tip; spathiform calyx splitting along a single line |