| 1 | Leaves (pseudo-)verticillate |
| 1' | Leaves not verticiliate. |
| 2 | Inflorescence only 1-flowered. |
| 2' | Inflorescence more-flowered. |
| 3 | Calyx and ovary glabrous. |
| 3' | Calyx and/or ovary hairy. |
| 4 | Ovary hairy |
| 4' | Ovary glabrous |
| 5 | Calyx and ovary glabrous. |
| 5' | Calyx and/or ovary hairy. |
| 6 | Twigs hairy. |
| 6' | Twigs glabrous. |
| 7 | Petiole 0 to 5 mm. |
| 7' | Petiole more than 5 mm. |
| 8 | Underside of leaves glabrous. |
| 8' | Underside of leaves hairy. |
| 9 | Upper side of leaves hairy. Ovary c. ¾ mm long |
| 9' | Upper side of leaves glabrous. Ovary more than 1 mm high. |
| 10 | Bracts caducous. Calyx lobes becoming longer by tearing '. |
| 10' | Bracts persistent. Calyx lobes not becoming longer by tearing. |
| 11 | Underside of leaves hairy. |
| 11' | Underside of leaves glabrous. |
| 12 | Bracts caducous. |
| 12' | Bracts persistent. |
| 13 | Bracts longer than 3 mm. |
| 13' | Bracts shorter than c. 3 mm. |
| 14 | Ovary c. 1 mm long. Inflorescence a (basally branched) raceme. |
| 14' | Ovary more than 1 mm high. Inflorescence different. |
| 15 | Disk hairy. Ovary 1-1½ mm. Inflorescence a panicle |
| 15' | Disk glabrous. Inflorescence an often branched spike. |
| 16 | Inflorescence not a spike. |
| 16' | Inflorescence a (basally branched) spike. |
| 17 | Inflorescence a fascicle. |
| 17' | Inflorescence a panicle |
| 18 | Twigs not thick. |
| 18' | Twigs thick. |
| 19 | Leaves 6-12 cm. Petiole 5-25 mm. Inflorescence an (often branched) spike. Flowers bisexual, ovary 1-1½ mmi calyx ¼-¾ mm |
| 19' | Plants different. Flowers usually functional unisexual. |
| 20 | Terminal buds hairy, small. Acumen longer than 5 mm. Bracts hairy, shorter than 3 mm. Disk hairy. Leaves elliptic or circular. |
| 20' | Terminal buds glabrous, large. Acumen shorter than 5 mm. Bracts glabrous, 5-7 mm. Disk glabrous. Leaves obovate |
| 21 | Ovary glabrous. |
| 21' | Ovary hairy. |
| 22 | Ovary hidden by bracts and bracteoles. |
| 22' | Ovary not hidden by bracts and bracteoles. |
| 23 | Inflorescence a spike, forming a short cone in bud |
| 23' | Inflorescence sometimes a spike, but never forming a cone in bud. |
| 24 | Twigs at least 8 mm thick. Leaves 21-62 cm |
| 24' | Twigs thinner. Leaves at most 33 cm, but usually much smaller. |
| 25 | Calyx 2- to 4-lobed or symmetrically cleft. Calyx lobes becoming longer by tearing. |
| 25' | Calyx regularly 5-lobed. |
| 26 | Disk glabrous. |
| 26' | Disk hairy. |
| 27 | Bracts and bracteoles caducous |
| 27' | Bracts persistent. |
