| | 1. Inflorescence a peduncled pair of flowers |
| |
| | 2. Corolla > 25 mm; climbing vine |
| L. japonica |
| | 2' Corolla < 20 mm; erect shrub |
| |
| | 3. Ovaries of flower pair fused or appearing so |
| |
| | 4. Corolla yellowish, weakly 2-lipped; bracts generally 1–3, narrowly lanceolate; ovaries and berries tightly enclosed by fused inner bracts, appearing fully fused |
| L. cauriana |
| | 4' Corolla dark red, strongly 2-lipped; bracts 0 or minute; ovaries and berries fused ± 2/3 |
| L. conjugialis |
| | 3' Ovaries of flower pair obviously free |
| |
| | 5. Bracts not leafy, not obscuring ovaries |
| L. tatarica |
| | 5' Bracts leafy, forming a conspicuous involucre, ± enveloping ovaries |
| L. involucrata |
| | 6. Plant generally < 9 dm; corolla yellow, tube ± wider upward; style and stigma well exserted; montane |
| var. involucrata |
| | 6' Plant generally > 15 dm; corolla yellow, strongly tinged orange or red, tube cylindric; stigma rarely exserted; coastal |
| var. ledebourii |
| | 1' Inflorescence a spike, generally ± interrupted — twining or trailing shrubs |
| |
| | 7. Ovary/hypanthium long, slender, generally sterile — see note after generic description |
| |
| | 7' Ovary/hypanthium short, round, fertile |
| |
| | 8. Leaf 5–10 cm; corolla 15–40 mm; inflorescence a dense, short spike; upper leaf pair fused around stem; Northwestern California, Cascade Range |
| |
| | 9. Corolla orange, weakly 2-lipped; stamens and style little exserted |
| L. ciliosa |
| | 9' Corolla ± yellowish white, strongly 2-lipped; stamens and style well exserted |
| L. etrusca |
| | 8' Leaf 1–8 cm; corolla generally < 15 mm; inflorescence a ± long, interrupted spike; upper leaf pair fused around stem or not; widespread |
| |
| | 10. Upper leaf pairs fused around stem; corolla hairy or not |
| |
| | 11. Leaves generally with ± obvious stipules, at least toward inflorescence; corolla glandular-hairy |
| L. hispidula var. vacillans |
| | 11' Leaves without stipules; corolla glabrous |
| L. interrupta |
| | 10' Upper leaf pairs not fused around stem; corolla often hairy |
| L. subspicata |
| | 12. Leaf < 2 × longer than wide; widespread (including Santa Barbara Co.) |
| var. denudata |
| | 12' Leaf 3–4 × longer than wide; Western Transverse Ranges (Santa Barbara Co.) |
| var. subspicata
|