| | 1. Leaf-bundle sheath deciduous or mostly so; seed cone scale tip generally without prickle |
| |
| | 2. Leaves generally < 5 per bundle |
| |
| | 3. Leaves generally 4 (3–5) per bundle |
| P. quadrifolia |
| | 3' Leaves generally 1–2 per bundle |
| |
| | 4. Leaves generally 2 per bundle |
| P. edulis |
| | 4' Leaves generally 1 per bundle |
| P. monophylla |
| |
| | 5. Seed cone generally torn apart by animals, generally not on ground intact; seed wings persistent on scale |
| P. albicaulis |
| | 5' Seed cone not torn apart by animals, generally on ground intact; seed wings persistent on scale or not |
| |
| | 6. Seed cone scale thinnest at tip, without prickle |
| |
| | 7. Seed cone stalk < 2 cm; seed wings narrow, generally persistent on scale |
| P. flexilis |
| | 7' Seed cone stalk > 2 cm; seed wings broad, deciduous from scale |
| |
| | 8. Seed cone generally > 20 cm; mature bark thick, reddish brown |
| P. lambertiana |
| | 8' Seed cone generally < 20 cm; mature bark thin, dark gray |
| P. monticola |
| | 6' Seed cone scale thickest at tip, with prickle |
| |
| | 9. Scale knob tip with 2–6 mm prickle; trunks often multiple |
| P. longaeva |
| | 9' Scale knob tip with < 1 mm prickle; trunks generally single |
| P. balfouriana |
| | 10. Leaf ± yellow-green; bark reddish brown, in ± square plates; s Sierra Nevada, East of Sierra Nevada |
| subsp. austrina |
| | 10' Leaf ± blue-green; bark gray-brown, in ± narrow ridges; Klamath Ranges, High North Coast Ranges |
| subsp. balfouriana |
| | 1' Leaf-bundle sheath persistent; seed cone scale tip with prickle, at least when immature (sometimes 0 at maturity) |
| |
| |
| | 12. Seed cone > 5 cm; leaf generally 5–15 cm |
| P. muricata |
| | 12' Seed cone < 5 cm; leaf 2.5–8.6 cm |
| P. contorta |
| | 13. Seed cone generally closed at maturity, asymmetric |
| subsp. bolanderi |
| | 13' Seed cone open at maturity, asymmetric or ± symmetric |
| |
| | 14. Seed cone persisting on stem many years after opening |
| subsp. contorta |
| | 14' Seed cone deciduous after opening |
| subsp. murrayana |
| | 11' Leaves 3 or 5 per bundle |
| |
| P. torreyana |
| |
| | 16. Basal seed cone scale tips recurved, elongated 3–7 cm; seed cone scale prickles generally worn off by maturity |
| |
| | 17. Seed cone yellowish; seed < wing; leaf dark green |
| P. coulteri |
| | 17' Seed cone brownish; seed > wing; leaf gray-green |
| P. sabiniana |
| | 16' Basal seed cone scale tips rarely recurved, then elongated < 3 cm; seed cone scales (except sometimes upper) with a rounded or angled, often prickled knob < 3 cm at maturity |
| |
| | 18. Seed cones persisting on stems many years after maturity |
| |
| | 19. Seed cone scale tips, except upper, with an angular knob > 2 cm |
| P. attenuata |
| | 19' Seed cone scale tips, except upper, with a rounded knob < 2 cm |
| P. radiata |
| | 18' Seed cones deciduous after maturity |
| |
| | 20. Seed cone generally < 9 cm; leaf generally 7–12 cm |
| P. washoensis |
| | 20' Seed cone generally > 9 cm; leaf generally > 15 cm |
| |
| | 21. Lower surface of seed cone scale generally not darker than upper; leaf grayish blue-green, glaucous; bark odor banana-, pineapple-, or vanilla-like |
| P. jeffreyi |
| | 21' Lower surface of seed cone scale generally darker than upper; leaf deep yellow-green; bark odor not banana-, pineapple-, or vanilla-like |
| P. ponderosa
|