| 1. Leaflet 512 cm; plant erect; tendrils 0 |
| V. faba |
| 1' Leaflet generally 14 cm; plant sprawling or climbing; tendrils generally present |
| |
| 2. Inflorescence a sessile or barely peduncled cluster of 14 pedicelled flowers |
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| V. lathyroides |
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| 4. Corolla pink-purple to whitish; banner glabrous, fruit initially hairy, quickly glabrous |
| V. sativa |
| 5. Calyx 712 mm; corolla 11.8 cm, pink-purple to ± white; naturalized, not cultivated |
| subsp. nigra |
| 5' Calyx 1015 mm; corolla 1.83 cm, generally pink-purple; cultivated and naturalized |
| subsp. sativa |
| 4' Corolla yellow or yellow-white, sometimes purple-blotched; banner puberulent on back, fruit persistently hairy, or both |
| |
| 6. Banner puberulent on back; calyx lobes ± equal; fruit hairs not from conspicuous tubercles |
| V. pannonica |
| 6' Banner glabrous; calyx lobes unequal; fruit hairs from tubercles conspicuous on lower margin of fruit |
| V. lutea |
| 2' Inflorescence a peduncled raceme |
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| |
| 8. Fruit hairy, stalk-like base 0; leaflets 1016; flowers generally 26 |
| V. hirsuta |
| 8' Fruit glabrous or ± strigose, stalk-like base ± 12 mm; leaflets, flowers various, including as above |
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| 9. Fruit rounded at tip, with a short point on 1 side, 11.3 cm; leaflets 410, linear to elliptic; peduncle thread-like, 13 cm, often curved, 13-flowered |
| V. tetrasperma |
| 9' Fruit tapered at tip, 13.5 cm; leaflets or peduncle not as above |
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| 10. Leaflets ± 1218; flowers 26; seeds 2 |
| V. disperma |
| 10' Leaflets 410; flowers 13; seeds generally > 2 |
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| 11. Style hairs clumped at tip, generally on lower, convex side; leaflet tip generally truncate; flowers well separated or 1 |
| V. hassei |
| 11' Style hairs at tip and below, on all sides; leaflet tip generally tapered; flowers crowded or 1 |
| V. ludoviciana var. ludoviciana |
| |
| 12. Leaf generally 11.5 dm; leaflets 1624, larger ones 2.54 cm fruit often upcurved, ± 1213 mm wide |
| V. gigantea |
| 12' Leaf rarely > 1 dm; leaflets either fewer or smaller than above |
| |
| 13. Flowers not crowded, on > 1 side of axis (except sometimes when pressed), 1.52.5 cm, length when pressed 2.53.5 × width; stalk-like fruit base 25 mm |
| V. americana var. americana |
| 13' Flowers crowded, generally on 1 side of axis, generally < 1.6 cm, length when pressed generally 46 × width; stalk-like fruit base 1.53 mm |
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| 14. Inflorescence ± = subtending leaf, 312-flowered; corolla dark or red-purple; fruit puberulent |
| V. benghalensis |
| 14' Inflorescence generally > subtending leaf, generally 1025-flowered; corolla blue-purple or lavender to ± white; fruit glabrous |
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| 15. Calyx often obliquely attached but only slightly lopsided-swollen at base; flower length when pressed ± 3-3.5 × width; fruit 67 mm wide; perennial herb |
| V. cracca |
| 15' Calyx both obliquely attached and lopsided-swollen at base; flowers when pressed 46 × width; fruit 610 mm wide; annual |
| V. villosa |
| 16. Hairs on stems, leaves 0 or inconspicuous, ± 1 mm; lower calyx lobe narrowly lanceolate, generally 12 mm |
| subsp. varia |
| 16' Hairs on upper stems, leaves conspicuous, 12 mm; lower calyx lobe needle- or thread-like, 24 mm |
| subsp. villosa
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