| | 1. Pedicels 3–10 cm, twining or with U-shaped hook |
| |
| | 2. Corollas of opening flowers yellow and gold; fruit fragile, opening by irregular bursting on sides |
| A. filipes |
| | 2' Corollas of opening flowers lavender to blue-purple; fruit firm, dehiscent by 2 slits at tip |
| A. kelloggii |
| | 1' Pedicels < 2.6 cm, not twining, not hooked |
| |
| | 3. Lowest flowers not subtended by branchlets; flowers all opening; annual to perennial herb; plants self-supporting |
| |
| | 4. Lower calyx lobes > or = corolla tube; seed smooth, 1 side flattened, with raised, rough, irregular border |
| A. orontium |
| | 4' Lower calyx lobes < to << corolla tube; seed with netted ridges or a cup-shaped wing |
| |
| A. majus |
| |
| | 6. Flowers in terminal racemes; corolla pale pink to red, 13–18 mm; often per from caudex |
| |
| A. multiflorum |
| A. virga |
| | 6' Flowers solitary in leaf axils; corolla generally white, cream, or pale lavender, often with violet or purple veins or marks, 7–14 mm; annual |
| |
| | 8. Pedicel in fruit bending down; fruit chambers equal; seed wing large, cup-shaped |
| A. cyathiferum |
| | 8' Pedicel in fruit not changing orientation; fruit chambers unequal; seed wing 0 |
| |
| | 9. Corolla white, veins violet; swollen lower lip base with dense, cylindric hairs |
| A. cornutum |
| | 9' Corolla white to pale lavender, veins not contrasting in color; swollen lower lip base with sparse, sphere-tipped hairs |
| A. leptaleum |
| | 3' Lowest flowers and often others generally subtended by branchlets; flowers cleistogamous or opening; annual, rarely biennial; plants often not self-supporting, climbing or sprawling |
| |
| |
| | 11. Plant hairy only in inflorescence; upper fruit chamber indehiscent |
| A. coulterianum |
| | 11' Plant hairy throughout; both fruit chambers dehiscent |
| A. nuttallianum |
| | 12. Hairs very dense, very fine, of mixed lengths, with ± unenlarged tips |
| subsp. nuttallianum |
| | 12' Hairs sparse to moderately dense, coarse, of ± uniform length, with much-enlarged tips |
| subsp. subsessile |
| |
| | 13. Flowers cleistogamous or opening; corollas of opening flowers 5–7 mm, white, veins violet |
| A. kingii |
| | 13' Flowers opening; corollas 8–20 mm, white to tan, cream and pink, or lavender |
| |
| | 14. Corolla lower lip base not swollen, not closing mouth, throat floor with 2 longitudinal folds |
| A. ovatum |
| | 14' Corolla lower lip base swollen, closing mouth, throat floor without folds |
| |
| | 15. Corollas white to tan, throat floor expanded at mouth, lower lip lobes reflexed, poorly developed |
| A. subcordatum |
| | 15' Corolla lavender, throat uniformly narrowed at mouth, lower lip lobes thrust forward, erect or spreading, conspicuous |
| A. vexillo-calyculatum |
| | 16. Lower stem glabrous or with only nonglandular hairs; corollas 11–17 mm — San Francisco Bay Area and nearby |
| subsp. vexillo-calyculatum |
| | 16' Lower stem glandular-hairy, with or without nonglandular hairs; corollas 8–14 mm |
| |
| | 17. Branchlets subtending flowers with 1 leaf at lowest node; nw California |
| subsp. breweri |
| | 17' Branchlets subtending flowers generally with 2 leaves at lowest node; Sierra Nevada |
| subsp. intermedium
|