| 1 | Adult leaves in the form of imbricate scales [microsporophylls triangular]. |
| 1' | Adult leaves spreading linear or lanceolate needles or leaves. |
| 2 | Mature seed completely exposed above short (to 2 mm) cone bracts; juvenile leaves nearly straight, up to twice as wide as thick; adult scales appearing gradually on trees several meters high. |
| 2' | Mature seed base overlapped by elongated (3 mm) cone bracts; juvenile leaves strongly bent forward and slightly inward, about three times as wide as thick, adult scales appearing almost abruptly on small specimens about half a metre high |
| 3 | Microsporophylls triangular; female terminal (occasionally on short lateral branches); leaves bent forward, up to 5 mm long and length about 5 times width. |
| 3' | Microsporophylls sharply narrowed above the pollen sacs and lanceolate; female may be lateral in some species; leaves acute, in many species to more than 5 mm long and length generally at least 8 times width. |
| 4 | Leaves blunt (may be apiculate), width less than twice thickness. |
| 4' | Leaves acute, width more than twice thickness |
| 5 | Mature seed fully exposed above short cone bracts [leaves robust (0.3-0.4 mm thick)] |
| 5' | Mature seed barely overtopping elongated cone bracts. |
| 6 | Leaves spreading their tips bent parallel to the branch or directed outward, blunt or with a small apiculus, becoming triangular in cross section and about as thick as wide, 0.2-0.3 mm thick |
| 6' | Leaves crowded and more or less touching near their tips which on mature plants curve inward towards the branch, distinctly apiculate, nearly twice as wide as thick, 0.3-0.4 mm thick |
| 7 | Leaves triangular in cross section, width no more than three times thickness. |
| 7' | Leaves distinctly concave on the underside or wide and flat, width at least 8 times thickness. |
| 8 | Leaves spreading (nearly straight), 0.3-0.4 mm wide, less than twice thickness, length about 25 times width |
| 8' | Leaves bent forward, 0.4-0.6 mm wide and width 2-3 times thickness, length no more than 12 times width. |
| 9 | Leaves mostly 0.4 mm wide; male 6-7 mm long; microsporophyll barely 1 mm long; mature seed exposed |
| 9' | Leaves up to 0.6 mm wide; male more than 7 mm long; microsporophyll 1.5-2 mm long; mature seed partly covered by elongated cone bracts. |
| 10 | Leaves slightly bent forward, length up to 10 times width; male 7-9 mm long. |
| 10' | Leaves strongly bent forward, length more than 10 times width; male about 12 mm long |
| 11 | Leaves at least 3 mm long. |
| 11' | Leaf about 1 mm long, strongly bent forward |
| 12 | Female terminal, bracts about as long as leaves, mature seed partly covered; leaves up to 7 mm long, apex abrupt and bent forward. |
| 12' | Female mostly lateral, bracts much smaller than leaves, mature seed exposed; leaves at least 6 mm long. |
| 13 | Leaves 3-5 mm long, only slightly bent (male unknown) |
| 13' | Leaves 5-7 mm long, strongly bent; microsporophyll very long (5-6 mm) |
| 14 | Leaves slightly bent forward and concave, lanceolate, narrowly acute. |
| 14' | Leaves straight and flat, linear, more or less abrupt at the apex, up to 10 mm long |
| 15 | Leaves 6-10 mm long, 0.5-0.8 mm wide |
| 15' | Leaves at least 10 mm long, 0.7-1.3 mm wide |
