| | 1. Petals red; staminodes pink; sepals lanceolate, ciliate; stigmas ± = styles in width |
| L. grandiflorum |
| | 1' Petals blue, white, yellow, or orange; staminodes white; sepals linear to ovate, margins generally glabrous or gland-toothed; stigmas > styles in width |
| |
| | 2. Petals yellow to orange; margins of leaves, bracts, and sepals gland-toothed; styles fused to near tip |
| L. puberulum |
| | 2' Petals blue to white; margins of leaves, bracts, and sepals generally entire, glabrous; styles free or fused only near base |
| |
| L. lewisii |
| | 4. Petals 6–7 mm; styles < 6 mm |
| var. alpicola |
| | 4' Petals 10–15 mm; styles generally > 6 mm |
| var. lewisii |
| |
| | 5. Petals 8–10 mm; pedicels 5–18 mm; sepals 4–6 mm; fruit 4–5 mm |
| L. bienne |
| | 5' Petals 10–15 mm; pedicels 20–25 mm; sepals 6–10 mm; fruit 7–10 mm |
| L. usitatissimum
|