| | 1. Stipule leaf-like, ± = leaf, pinnately lobed; generally annual; alien |
| |
| | 2. Petals generally < sepals, mostly cream, sometimes with some blue-violet on upper 4, spur ± = sepal appendages |
| V. arvensis |
| | 2' Petals generally > sepals, mainly blue-violet (rarely yellow), spur > sepal appendages — sometimes per |
| V. tricolor |
| | 1' Stipule not leaf-like, << leaf, entire or toothed; perennial herb; generally native |
| |
| | 3. Leaf dissected to compound |
| |
| | 4. Cleistogamous flowers present, sometimes exclusively; leaf blade generally wider than long |
| V. sheltonii |
| | 4' Cleistogamous flowers 0; leaf blade generally longer than wide |
| |
| | 5. Upper 2 petals golden-yellow on front, brown to very dark on back |
| V. douglasii |
| | 5' Upper 2 petals dark red-violet |
| |
| | 6. Lower 3 petals bluish to white, bases with yellow area; stem glabrous to puberulent |
| V. beckwithii |
| | 6' Lower 3 petals cream, bases with deep yellow area; stem glabrous |
| V. hallii |
| | 3' Leaf generally ± entire to deeply lobed (seldom dissected) |
| |
| | 7. Petals white to blue or purple, without yellow |
| |
| | 8. Stem branched; leaves basal and cauline |
| V. adunca |
| |
| | 9. Petals white, dark-veined or not |
| |
| | 10. Leaf blade elliptic to ovate, longer than wide — nw Klamath Ranges, 100–500 m |
| V. primulifolia subsp. occidentalis |
| | 10' Leaf blade ovate to reniform, generally as wide as or wider than long |
| |
| | 11. Rhizome < 5 mm diam; spur white; leaf blade thin, not leathery, (sub)entire; native; mtns |
| V. macloskeyi |
| | 11' Rhizome 5–20 mm diam; spur violet; leaf blade thick, leathery, ± toothed; alien; San Francisco Bay Area, South Coast |
| 2 V. odorata |
| | 9' Petals blue (sometimes very pale) to purple |
| |
| | 12. Leaf glabrous; rhizome thin; North Coast |
| V. palustris |
| | 12' Leaf ± glabrous or finely hairy; rhizome thick; Klamath Ranges, San Francisco Bay Area, South Coast, San Bernardino Mountains, Warner Mountains, East of Sierra Nevada |
| |
| | 13. Plant stoloned; leaf finely hairy; alien; San Francisco Bay Area, South Coast |
| 2 V. odorata |
| | 13' Plant not stoloned; leaf ± glabrous; native; Klamath Ranges, San Bernardino Mountains, Warner Mountains, East of Sierra Nevada |
| V. sororia subsp. affinis |
| | 7' Petals yellow to ± orange, or white with yellow base and spur |
| |
| | 14. Petals white inside, with generally yellow base and spur, lower 3 veined purple-red |
| |
| | 15. Leaf blade base generally tapered; basal blade midvein 10–40 mm; plant glabrous |
| V. cuneata |
| | 15' Leaf blade base generally truncate to deeply cordate; basal blade midvein 10–60 mm; plant finely hairy |
| V. ocellata |
| | 14' Petals yellow to ± orange inside, generally veined dark brown to purple |
| |
| | 16. Stems few, erect, unbranched below; basal leaves 0–4; cauline leaves and peduncles restricted to upper stem |
| |
| | 17. Upper 2 petals yellow outside; cauline leaf ovate-cordate to widely reniform; moist places |
| V. glabella |
| | 17' Upper 2 petals purple to brown-purple outside; cauline leaf diamond-shaped to reniform, entire to dissected; dry places |
| V. lobata |
| | 18. Cauline leaf diamond-shaped to generally deltate, entire to toothed |
| subsp. integrifolia |
| | 18' Cauline leaf ± ovate to generally reniform, palmately lobed or dissected, segments 3–12, generally entire |
| subsp. lobata |
| | 16' Stems 0–many, prostrate to erect, branched below; basal leaves 0–6; cauline leaves and peduncles on lower and upper stem |
| |
| | 19. Plant stoloned; leaf evergreen, leathery, generally purple-spotted on 1 or both sides — coastal forests |
| V. sempervirens |
| | 19' Plant not stoloned; leaf not evergreen, not leathery, not purple-spotted |
| |
| | 20. Basal leaves 0; cleistogamous flowers 0; petals orange-yellow — fruit glabrous |
| V. pedunculata |
| | 20' Basal leaves 1–6; cleistogamous flowers present; petals yellow to lemon-yellow |
| |
| | 21. Basal blade 1.5–6 × longer than wide, 15–80 mm, linear to obovate; cauline blade 2–10 × longer than wide |
| |
| | 22. Plant white-tomentose — n&c High Sierra Nevada |
| V. tomentosa |
| | 22' Plant glabrous to densely hairy (not white-tomentose) |
| |
| | 23. Leaf generally entire |
| V. bakeri |
| | 23' Leaf toothed, jagged, or wavy (seldom entire) |
| |
| | 24. Cauline leaf blade 3–25 mm wide, linear to ± ovate; peduncle 20–90 mm |
| V. pinetorum |
| | 25. Plant canescent, 4–10 cm; leaves 3–10 mm wide, basal 40–95 mm, cauline 30–80 mm — s High Sierra Nevada |
| subsp. grisea |
| | 25' Plant glabrous to hairy, 6–22 cm; leaves 4–25 mm wide, basal 50–200 mm, cauline 30–150 mm |
| subsp. pinetorum |
| | 24' Cauline leaf blade 14–45 mm wide, elliptic to ± ovate; peduncle 40–180 mm |
| V. praemorsa |
| | 26. Cauline leaf blade much longer than wide, generally irregularly toothed or wavy, base generally tapered |
| subsp. linguifolia |
| | 26' Cauline leaf blade slightly longer than wide, generally regularly toothed, base ± truncate to subcordate |
| subsp. praemorsa |
| | 21' Basal blade generally 1–1.5 × longer than wide, 10–50 mm, ovate to round; cauline blade generally < 2.5 × longer than wide |
| |
| | 27. Leaf canescent above; plant generally 6–13 cm; peduncle 30–100 mm; uncommon — East of Sierra Nevada, Mojave Desert |
| V. aurea |
| | 27' Leaf glabrous to hairy (not canescent) above; plant 1–35 cm; peduncle 15–170 mm; widespread |
| V. purpurea |
| | 28. Plant 1–12 cm; stem generally buried, little branched or elongated by late summer; lower petal (including spur) generally < 11 mm |
| |
| | 29. Cauline leaf generally entire; plant 1–12 cm |
| subsp. integrifolia |
| | 29' Cauline leaf generally crenate to deeply toothed; plant 4–11 cm |
| subsp. venosa |
| | 28' Plant 4–35 cm; stem generally not buried, clearly branched and elongated above by late summer; lower petal (including spur) generally > 11 mm |
| |
| | 30. Cauline leaf deeply toothed |
| subsp. mohavensis |
| | 30' Cauline leaf entire, jagged, shallowly toothed, or lobed |
| |
| | 31. Leaf generally green tinged purple, generally glabrous above; lower petal (including spur) generally < 13 mm; peduncle generally < 13 cm; 500–2500 m, generally montane forest |
| subsp. purpurea |
| | 31' Leaf generally gray-green (± without purple), puberulent; lower petal (including spur) generally 13+ mm, or peduncle > 13 cm, or both; 400–1800 m, generally foothill communities |
| subsp. quercetorum
|