In Vicia, the style is glabrous except for a tuft or fringe of hairs at the summit, just below the stigma. In Lathyrus, the style has a longer strip of pubescence. Only two of our species are native in North America. The others are all European, doubtless originally grown for forage or as a cover crop.
1. Inflorescences sessile or on peduncles shorter than the leaflets, 1–2-flowered.
2. Calyx oblique at apex, the teeth unequal (upper ones smaller) and all less than half as long as the tube and less than 2 mm long; perennials.
2. Calyx not oblique, the teeth ± equal, ca. half as long as the tube or longer and more than 2 mm long; annuals.
3. Corolla yellow (sometimes marked or suffused with purplish), ca. 25–35 mm long; calyx teeth clearly shorter than the tube.
3. Corolla blue to purple (or white), ca. 5–16 (–30) mm long; calyx teeth nearly or quite as long as the tube.
4. Corolla ca. (10–) 13–16 (–30) mm long; most tendrils branched.
4. Corolla ca. 5–8 mm long; most tendrils unbranched.
1. Inflorescences on peduncles longer than the leaflets, with usually more than 2 flowers.
4. Leaflets with ca. 10 or more pairs of firm lateral veins running nearly or quite to the margins; stipules with several teeth or lobes; inflorescences slightly exceeded by subtending leaves, 3–8-flowered.
4. Leaflets with ca. 6 or fewer pairs of lateral veins running nearly or quite to the margins; stipules at most with 1 basal lobe; inflorescences shorter or longer than the leaves.
5. Flowers less than 6 (–8) mm long, 1–6 (–7) in an inflorescence; calyx teeth (at least the longer ones) about as long as or longer than the tube.
6. Calyx teeth ± equal; fruit pubescent, (6–) 8–9 (–10) mm long, 2-seeded.
6. Calyx teeth unequal, the calyx clearly oblique; fruit glabrous, 10–13 mm long, mostly 4-seeded.
5. Flowers at least 8 mm long, (8–) 12–40 or more in an inflorescence; calyx teeth often shorter than the tube.
7. Calyx ca. 3 mm long or shorter, the teeth deltoid (about as long as broad), ± equal; corolla white (except for blue-tipped keel) or occasionally tinged with blue.
7. Calyx ca. 3.5–8 (–9) mm long, the teeth elongate (at least the lower ones) and distinctly unequal; corolla (except in albinos) blue to purple (or rarely pink).
8. Calyx not extended beyond the pedicel, which appears basal (though off-center); blade of standard about equaling the claw; stem and pedicels with mostly appressed or incurved pubescence.
8. Calyx projecting at its base beyond the attachment of the pedicel, the latter thus appearing subterminal or ventral; blade of standard about half as long as the claw or shorter; stem and pedicels usually covered with fine spreading hairs (rarely glabrate).