| 1 | Sepals ≥ 2 times as long as wide; corolla tube ≥ 9 mm long; anthers obtuse to acute; leaves with or without submarginal veins |
| 1' | Sepals ≤ 1.5 times as long as wide; corolla tube < 6 mm long; anthers cuspidate; leaves with submarginal veins |
| 2 | First branch of inflorescence less than 0.3 cm long; flowers clustered; carpels connate at base; mericarps subglobose or ovoid, connate at base |
| 2' | First branch of inflorescence more than 0.5 cm long; inflorescence lax; carpels free from each other; mericarps globose or ellipsoid, free from each other |
| 3 | Leaf blade thinly papyraceous; inflorescences in whorls of 2 or 3, with fewer than 10 flowers; fruits subglobose to globose, red when mature |
| 3' | Leaf blade papyraceous; inflorescences in whorls of 3 or 4, with 8-more than 35 flowers; fruits ovoid, whitish purple when mature |
| 4 | Leaf blade papyraceous or thinly so; inflorescence with fewer than 8 flowers |
| 4' | Leaf blade subcoriaceous to coriaceous; inflorescence usually with more than 25 flowers |
| 5 | Inflorescence branches usually with many bracteoles; corolla tube ≤ 4 mm long; fruits obversely trapezoid, with 2 acute apices |
| 5' | Inflorescence branches with few bracteoles or absent; corolla tube > 5 mm long; fruits ovoid, with 1 rounded apex |
| 6 | Corolla tube 2-2.4 mm long; disk serrate; petiole and midrib yellowish when dried |
| 6' | Corolla tube 2.6-4.9 mm long; disk crenate; petiole and midrib not yellowish when dried |
| 7 | Corolla tube 2.4-3.4 times as long as the calyx; fruits globose or subglobose, apex of mericarps rounded to cleft (when cleft, distance between apices ≤ 0.3 of fruit length) |
| 7' | Corolla tube 1.5-2.2 times as long as the calyx; fruits obversely trapezoid, apex of mericarps widely split into 2 acute apices, distance between apices > 0.3 of fruit length |
| 8 | Disk less than 0.45 times as long as the ovary. — Moluccas, New Guinea |
| 8' | Disk more than 0.6 times as long as the ovary. — Sumatra, Java, Lesser Sunda Islands |
