| | 1. Roots fibrous or slightly thickened, generally 5–20-clustered; styles generally < 1 mm |
| |
| | 2. Leaflets widely lanceolate to ovate, 10–40 mm wide; petals 5–7-veined; fruit ribs prominent |
| P. howellii |
| | 2' Leaflets linear to lanceolate, 2–8 mm wide; petals 1-veined; fruit ribs thread-like |
| P. kelloggii |
| | 1' Roots tuberous, single or 2–6-clustered; styles generally 1–2.5 mm |
| |
| | 3. Basal leaves 1–2-ternate or 1–2-pinnate with 1–3 pairs of 1° leaflets |
| |
| | 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 3–4 |
| P. parishii |
| | 5. Rays generally 12–14, in fruit subequal; bractlets ± = pedicels; fruit ovate to nearly round, 2.5–3.5 mm |
| subsp. latifolia |
| | 5' Rays generally 6–11, in fruit unequal; bractlets generally < pedicels; fruit oblong to ± ovate, 3–5 mm |
| subsp. parishii |
| | 3' Basal leaves ± 1-pinnate with 3–5 pairs of 1° leaflets or 2–3-pinnately or ternate-pinnately dissected or compound |
| |
| | 6. Basal leaves ± 1-pinnate with 3–5 pairs of 1° leaflets, lower 1° leaflets sometimes lobed or ternately dissected |
| P. gairdneri |
| | 7. Tuberous roots 2–3-clustered; petals 5- or 7-veined |
| subsp. borealis |
| | 7' Tuberous roots single; petals 1-veined |
| subsp. gairdneri |
| | 6' Basal leaves 2–3-pinnately or ternate-pinnately dissected or compound |
| |
| | 8. Terminal leaf segments unlike lateral in size or form |
| |
| | 9. Fruit generally not > 6 mm; bractlets wholly scarious, 3–9 mm, acuminate |
| P. bolanderi subsp. bolanderi |
| | 9' Fruit 5–8 mm; bractlets scarious-margined, 1–4 mm, acute |
| |
| | 10. Plant 5–15 dm; tuberous roots cylindric, 5–12 cm; leaf segments flattened, 5–10 mm wide; oil tubes per rib-interval 1 |
| P. californica |
| | 10' Plant 3.5–7.5 dm; tuberous roots oblong to ovoid, 1–6 cm; leaflets cylindric, < 1 mm wide; oil tubes per rib-interval 3–4 |
| 2 P. pringlei |
| | 8' Leaf segments or leaflets all similar in size or form |
| |
| | 11. Longest rays in fruit 5–9 cm |
| |
| | 12. 2° umbels generally spheric, generally 40–50-flowered; umbels slightly concave on top, rays very unequal; oil tubes per rib-interval 1 |
| P. bacigalupii |
| | 12' 2° umbels convex on top, generally 20–25-flowered; umbels convex on top, rays subequal; oil tubes per rib-interval 3–4 |
| 2 P. pringlei |
| | 11' Longest rays in fruit 1.5–3 cm |
| |
| | 13. Bracts 0–2, inconspicuous |
| |
| | 14. Umbels strongly concave on top; rays in fruit very unequal; fruit linear-club-shaped, 5–7 mm |
| P. leptocarpa |
| | 14' Umbels convex or flat on top; rays in fruit subequal; fruit oblong, 3–6 mm |
| 2 P. oregana |
| | 13' Bracts 6–12, conspicuous |
| |
| | 15. Bractlets widely scarious-margined, generally acuminate; oil tubes per rib-interval 2–3 |
| P. bolanderi subsp. involucrata |
| | 15' Bractlets scarious-margined, acute; oil tubes per rib-interval 1 |
| 2 P. oregana
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