| 1. Roots fibrous or slightly thickened, generally 520-clustered; styles generally < 1 mm |
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| 2. Leaflets widely lanceolate to ovate, 1040 mm wide; petals 57-veined; fruit ribs prominent |
| P. howellii |
| 2' Leaflets linear to lanceolate, 28 mm wide; petals 1-veined; fruit ribs thread-like |
| P. kelloggii |
| 1' Roots tuberous, single or 26-clustered; styles generally 12.5 mm |
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| 3. Basal leaves 12-ternate or 12-pinnate with 13 pairs of 1° leaflets |
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| 4. Rays in fruit unequal, spreading-ascending; oil tubes per rib-interval 1 |
| P. lemmonii |
| 4' Rays in fruit subequal and ascending, or unequal and spreading-ascending; oil tubes per rib-interval 34 |
| P. parishii |
| 5. Rays generally 1214, in fruit subequal; bractlets ± = pedicels; fruit ovate to nearly round, 2.53.5 mm |
| subsp. latifolia |
| 5' Rays generally 611, in fruit unequal; bractlets generally < pedicels; fruit oblong to ± ovate, 35 mm |
| subsp. parishii |
| 3' Basal leaves ± 1-pinnate with 35 pairs of 1° leaflets or 23-pinnately or ternate-pinnately dissected or compound |
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| 6. Basal leaves ± 1-pinnate with 35 pairs of 1° leaflets, lower 1° leaflets sometimes lobed or ternately dissected |
| P. gairdneri |
| 7. Tuberous roots 23-clustered; petals 5- or 7-veined |
| subsp. borealis |
| 7' Tuberous roots single; petals 1-veined |
| subsp. gairdneri |
| 6' Basal leaves 23-pinnately or ternate-pinnately dissected or compound |
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| 8. Terminal leaf segments unlike lateral in size or form |
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| 9. Fruit generally not > 6 mm; bractlets wholly scarious, 39 mm, acuminate |
| P. bolanderi subsp. bolanderi |
| 9' Fruit 58 mm; bractlets scarious-margined, 14 mm, acute |
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| 10. Plant 515 dm; tuberous roots cylindric, 512 cm; leaf segments flattened, 510 mm wide; oil tubes per rib-interval 1 |
| P. californica |
| 10' Plant 3.57.5 dm; tuberous roots oblong to ovoid, 16 cm; leaflets cylindric, < 1 mm wide; oil tubes per rib-interval 34 |
| 2 P. pringlei |
| 8' Leaf segments or leaflets all similar in size or form |
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| 11. Longest rays in fruit 59 cm |
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| 12. 2° umbels generally spheric, generally 4050-flowered; umbels slightly concave on top, rays very unequal; oil tubes per rib-interval 1 |
| P. bacigalupii |
| 12' 2° umbels convex on top, generally 2025-flowered; umbels convex on top, rays subequal; oil tubes per rib-interval 34 |
| 2 P. pringlei |
| 11' Longest rays in fruit 1.53 cm |
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| 13. Bracts 02, inconspicuous |
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| 14. Umbels strongly concave on top; rays in fruit very unequal; fruit linear-club-shaped, 57 mm |
| P. leptocarpa |
| 14' Umbels convex or flat on top; rays in fruit subequal; fruit oblong, 36 mm |
| 2 P. oregana |
| 13' Bracts 612, conspicuous |
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| 15. Bractlets widely scarious-margined, generally acuminate; oil tubes per rib-interval 23 |
| P. bolanderi subsp. involucrata |
| 15' Bractlets scarious-margined, acute; oil tubes per rib-interval 1 |
| 2 P. oregana
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