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| 1 Leaves opposite or in whorls of 3. |
| ..2 Longest internodes 2-10 cm long; stems green, Equisetum-like |
| ..2 Longest internodes < 1 cm long; stems green, brown, or tan, not resembling Equisetum. |
| ....3 Leaves scale-like or acicular and <16 mm long; mature cones either dry and cone-like, or fleshy and < 9 mm in diameter |
| ....3 Leaves linear, 15-45 mm long; mature female “cones” fleshy and berry-like, > 15 mm in diameter |
| ......4 Leaves with distinct midrib on the upper surface; 2 stomatal bands on the lower surface each ca. 1 mm wide; berry-like “cone” stalked |
......4 Leaves without distinct midrib; 2 stomatal bands on the lower surface each ca. 0.5 mm wide; berrylike “cone” sessile |
| 1 Leaves either alternate, or in fascicles of 2-5 (basally bound by a scarious sheath), or on short shoots in clusters of many 10-60 leaves in apparent whorls. |
| ........5 Leaves either borne in fascicles of 2-5 (basally bound by a scarious sheath) (Pinus) or on short shoots in clusters of many leaves in apparent whorls (Cedrus, Larix) |
| ........5 Leaves alternate. |
| ..........6 Leaves 4-angled in cross-section. |
| ............ 7 Twigs green |
| ............ 7 Twigs brown or tan |
| ..........6 Leaves distinctly flattened (2-sided) in cross-section. |
| ............ ..8 Leaves very soft in texture, seasonally deciduous as twiglets; [primarily Coastal Plain] |
| ............ ..8 Leaves stiffer in texture, evergreen; [collectively more widespread]. |
| ............ ....9 Leaves tapering from base to a long-acuminate tip |
| ............ ....9 Leaves with parallel margins for most of their length, or widest near middle and gradually tapering to base and apex, the apex acute, obtuse, or retuse. |
| ............ ......10 Cone dry, brown, and woody at maturity |
| ............ ......10 ”Cone” fleshy, red or purplish at maturity |
| ............ ........11 Seed surrounded by a fleshy scale, appearing drupe-like, this also subtended by a swollen and fleshy receptacle |
| ............ ........11 Seed partially or fully enclosed in a fleshy aril, the subtending receptacle neither swollen nor fleshy |
| ............ ..........12 Leaves opposite or in whorls of 3; fleshy "cone" 2.5-3 cm long, ca. 2 cm in diameter, dark green to purple when ripe, seed entirely surrounded by fleshy tissue. |
| ............ ..........12 Leaves alternate; fleshy "cone" ca. 5 mm long, ca. 5 mm in diameter, red when ripe, the seed exposed at the top by a gap in the aril |