| 1 | Pollen cones solitary or in groups of 3 or fewer. |
| 1' | Pollen cones regularly in clusters of more than 3. |
| 2 | Pollen cones regularly in threes or a mixture of threes and fewer (pollen cones usually at least 2.5 mm diam.; midrib more than 0.3 mm wide; ripe receptacle usually red). |
| 2' | Pollen cones normally solitary (only rarely grouped) (external bud scales erect and free; leaves not at all acuminate). |
| 3 | Primary foliage bud scales erect and free, secondary bud scales acute to acuminate. |
| 3' | Primary foliage bud scales imbricate, forming a globular ball; secondary bud scales blunt. Spp. 11-12 |
| 4 | Secondary bud scales broadly acute, primary bud scales generally less than four times as long as broad; adult leaves not acuminate, usually not abruptly expanded at the base. Spp. 1-8 |
| 4' | Secondary bud scales acuminate, primary bud scales more than four times as long as broad; adult leaves acuminate, abruptly expanded at the base. Spp. 9-10 |
| 5 | Foliage buds much longer than wide (with long lanceolate scales), secondary bud scales acuminate. Bracts below the receptacle usually at least 3 mm long (ripe receptacle, red). Spp. 13-17 |
| 5' | Foliage buds less than twice as long as wide, secondary bud scales not acuminate. Bracts below the receptacle usually less than 2.5 mm long (midrib less than 0.3 mm wide). |
| 6 | Pollen cones less than 3 mm diam., apex of the microsporophyll less than 0.5 mm long. Foliage bud less than 2 mm diam. Spp. 18-21 |
| 6' | Pollen cones more than 3.5 mm diam., apex of the microsporophyll more than 1 mm long. Foliage bud mostly more than 2 mm diam. Ripe receptacle usually purple or black. Spp. 22-25. |
| 7 | Outer bud scales imbricate, apex of the scales slightly if at all raised. Midrib on the upper side of the leaf broad and flat. Ripe receptacle red. Spp. 26-27 |
| 7' | Outer bud scales erect and free. Midrib narrow and in most species prominently raised. Ripe receptacle usually purple. Spp. 28-30 |
