| 1. Leaflets 0; stipules leaflet-like; corolla bright yellow |
| L. aphaca |
| 1' Leaflets 216; stipules generally not leaflet-like; corolla purple to white (sometimes fading to dull yellow) or (in L. sulphureus) yellow to bronze-orange (drying tan or dark) |
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| 2. Leaflets 2; aliens of disturbed habitats |
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| 4. Inflorescence 415-flowered; wings of stem, petiole often > 2 mm wide |
| L. latifolius |
| 4' Inflorescence 14-flowered; wings of stem, petiole < 2 mm wide |
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| 5. Fruit hairy; leaflets ovate to elliptic, length 1.23 × width |
| L. odoratus |
| 5' Fruit glabrous; leaflets ovate to lanceolate, length 1.26.5 × width |
| L. tingitanus |
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| 6. Fruit hairy; inflorescence 12-flowered; calyx tube ± = lobes |
| L. hirsutus |
| 6' Fruit glabrous; inflorescence 1-flowered; calyx tube << lobes |
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| 7. Inflorescence axis not extended beyond flower; calyx tube << lobes; corolla red-purple |
| L. cicera |
| 7' Inflorescence axis extended as a bristle beyond flower; calyx tube ± = or < lobes; corolla not red-purple |
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| 8. Peduncle 28 cm; corolla lavender or purple; fruit veins indistinct, netted |
| L. angulatus |
| 8' Peduncle 0.52 cm; corolla orange-red; fruit veins distinct, longitudinal |
| L. sphaericus |
| 2' Leaflets 216 (> 2 at least on some leaves); natives of diverse natural habitats |
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| 9. Leaflet, fruit gland-dotted; leaflets ± 1416 North Coast Ranges |
| L. glandulosus |
| 9' Leaflet, fruit not gland-dotted; leaflets often < 14 |
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| 10. Stem winged, the wings ± 1 mm or more wide |
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| 11. Leaflets generally 6, opposite; coastal marshes, North Coast |
| 2 L. palustris |
| 11' Leaflets generally 816, irregularly arranged; not of immediate coast, except in San Francisco Bay Area |
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| 12. Corolla 1015 mm, white (sometimes dark-striate), fading dull yellow; Klamath Ranges |
| 2 L. delnorticus |
| 12' Corolla 1520 mm, pink to pink-purple; widespread |
| L. jepsonii |
| 13. Plant generally puberulent; Klamath Ranges to South Coast Ranges, s Sierra Nevada, except San Francisco Bay Area |
| var. californicus |
| 13' Plant glabrous; Great Central Valley but generally coastal marshes in San Francisco Bay Area |
| var. jepsonii |
| 10' Stem angled or flanged, the angles or flanges < 1 mm wide |
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| 14. Tendrils not coiled or branched, often reduced to a short bristle |
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| 15. Stipule ± = or > leaflet; generally dunes or beaches of immediate coast North Coast |
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| 16. Plant glabrous or puberulent; leaflet 2.54.5 cm |
| 2 L. japonicus |
| 16' Plant gray-hairy; leaflet 12 cm |
| L. littoralis |
| 15' Stipule < leaflet; not of immediate coast |
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| 17. Inflorescence 12-flowered; leaflet generally 0.52 cm; fruit glabrous or puberulent |
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| 18. Leaflets 1015, ovate, 12 cm; fruit puberulent North Coast, North Coast Ranges, San Francisco Bay Area |
| L. torreyi |
| 18' Leaflets 48, generally oblong or narrowly lanceolate to linear; fruit glabrous |
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| 19. Leaflets 4, oblong-lanceolate, generally ± 0.51 cm; corolla greenish white, dark-striate; Outer North Coast Ranges (Humboldt Co.) |
| L. biflorus |
| 19' Leaflets of at least some leaves 48, narrowly lanceolate to linear, 1.58 cm; corolla pale lavender to purple; Klamath Ranges, High Sierra Nevada, Modoc Plateau |
| 4 L. lanszwertii var. aridus |
| 17' Inflorescence 216-flowered; leaflet 18 cm; fruit glabrous |
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| 20. Stems erect, many, clustered; flowers crowded; corolla white or pink-tinged, 1723 mm; Modoc Plateau |
| L. rigidus |
| 20' Stems erect or sprawling, solitary or a few clustered; flowers crowded or not; corolla lavender to pink-purple or, if white, < 17 mm; n California Floristic Province |
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| 21. Leaflets 1016, subopposite to alternate; stipules often ± as wide as leaflets; plant glabrous; Klamath Ranges, n&c North Coast Ranges |
| 2 L. polyphyllus |
| 21' Leaflets 410, irregularly arranged or opposite; stipules generally narrower than (to ± as wide as) leaflets; plant often hairy; widespread |
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| 22. Corolla 1325 mm; leaflets generally widely ovate or elliptic, generally opposite |
| 2 L. nevadensis var. nevadensis |
| 22' Corolla 712 mm; leaflets generally linear to lanceolate, irregularly arranged or opposite |
| 4 L. lanszwertii |
| 23. Corolla pale lavender to purple; Klamath Ranges, High Sierra Nevada, Modoc Plateau |
| var. aridus |
| 23' Corolla white to cream, often dark-striate; Klamath Ranges, North Coast Ranges |
| var. tracyi |
| 14' Tendrils, at least on some leaves, coiled and generally branched |
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| 24. Leaflets ± = stipules, 68; coastal beaches, dunes North Coast (Del Norte Co.) |
| 2 L. japonicus |
| 24' Leaflets generally > stipules, various in number, including 68; inland (except L. palustris of coastal marshes) |
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| 25. Corolla whitish yellow to bronze-orange (drying tan or dark), 1114 mm; banner reflexed above middle; inflorescence 10-15-flowered, generally dense, 1-sided flower appearing wide and blocky; North Coast Ranges, Sierra Nevada Foothills |
| L. sulphureus |
| 25' Corolla not whitish yellow to bronze-orange (sometimes fading tan-yellow), various in size, including 1114 mm; banner reflexed or bent from middle or below; inflorescence 115-flowered, generally ± open, rarely 1-sided |
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| 26. Corolla wine-red to crimson, 2535 mm; banner reflexed 120180° Peninsular Ranges (San Diego Co.) |
| L. splendens |
| 26' Corolla white to purple, 825 mm; banner bent ± 90° |
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| 27. Leaflets generally 6, opposite, glabrous or ± puberulent, and flowers 36 per inflorescence, 1520 mm; coastal marshes, North Coast |
| 2 L. palustris |
| 27' Leaflets, flowers not entirely as above; immediate coast only in San Francisco Bay Area |
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| 28. Stipules > 1 cm wide; leaflets 1016; Klamath Ranges, North Coast Ranges |
| L. polyphyllus |
| 28' Stipules < 1 cm wide and leaflets 12 or fewer (or not of Klamath Ranges, North Coast Ranges) |
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| 29. Inflorescence generally 24-flowered; Mojave Desert |
| L. hitchcockianus |
| 29' Inflorescence sometimes 216-flowered; not Mojave Desert |
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| 30. Corolla white or cream, fading yellow-tan North Coast, Klamath Ranges, North Coast Ranges |
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| 31. Stem flanged or narrowly winged; stipules widely triangular, 0.50.8 cm wide; Klamath Ranges |
| 2 L. delnorticus |
| 31' Stem angled or ± flanged; stipules generally lanceolate, < 0.5 mm wide; North Coast, Klamath Ranges, North Coast Ranges |
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| 32. Leaflets generally 46, glabrous or puberulent; corolla 912 mm |
| 4 L. lanszwertii var. tracyi |
| 32' Leaflets generally 812, glabrous; corolla 1416 mm |
| 2 L. vestitus var. ochropetalus |
| 30' Corolla purple, lavender, or reddish |
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| 33. Stipules > 1 cm wide; leaflets 1016 Klamath Ranges, North Coast Ranges |
| 2 L. polyphyllus |
| 33' Stipules < 1 cm wide; leaflets 412 |
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| 34. Flowers often crowded, generally 814, and corolla 1420 mm; leaflets 812, generally subopposite to alternate; w California Floristic Province |
| 2 L. vestitus |
| 35. Corolla dark purple to wine-red, 1620 mm; banner generally reflexed > 90°; South Coast, s Channel Islands, Peninsular Ranges |
| var. alefeldii |
| 35' Corolla pale lavender to purple, 1418 mm; banner bent ± 90°; Transverse Ranges and n |
| var. vestitus |
| 34' Flowers generally loosely spaced, either 210 and corollas 815 mm or 24 and corollas 1325 mm; leaflets 410, opposite or subopposite; especially Klamath Ranges, Cascade Range, Sierra Nevada |
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| 36. Leaflets generally opposite, generally widely ovate or elliptic; inflorescence 24-flowered; corolla 1325 mm |
| 2 L. nevadensis var. nevadensis |
| 36' Leaflets generally subopposite or irregularly arranged, ovate to linear; inflorescence 210-flowered; corolla 815 mm |
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| 37. Stipules widely ovate-triangular, often toothed, conspicuous; calyx glabrous except lobes often ciliate; corolla generally 1014 mm, banner little upcurved above other petals |
| L. brownii |
| 37' Stipules lanceolate, not toothed, often inconspicuous; calyx generally hairy; corolla 1016 mm, banner generally more reflexed than other petals |
| 4 L. lanszwertii var. lanszwertii
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