| | 1. Corolla pink to red, tube 16–25 mm, throat indistinct |
| |
| | 2. Leaves opposite or subopposite |
| |
| | 3. Leaf base generally subcordate; anther sacs 1.1–1.5 mm |
| K. cordifolia |
| | 3' Leaf base wedge-shaped; anther sacs 0.9–1 mm |
| K. corymbosa |
| | 2' Leaves whorled in 3's (sometimes a few opposite) |
| K. ternata |
| | 4. Calyx glandular, 3.8–5.5 mm |
| var. septentrionalis |
| | 4' Calyx glabrous, 4.5–7.2 mm |
| var. ternata |
| | 1' Corolla white, yellow, or brown-purple, short tube and distinct throat together 4–11 mm |
| |
| | 5. Corolla 11–16 mm, tube + throat > upper lip |
| |
| | 6. Inflorescence a panicle; flowers clearly pedicelled; anther sac valves spreading widely; staminode densely hairy; young stems glabrous, glaucous |
| K. lemmonii |
| | 6' Inflorescence spike-like; flowers ± sessile; anther sac valves barely spreading; staminode glabrous near tip; young stems densely short-hairy, green |
| K. rothrockii |
| | 7. Corolla 13–15 mm, sparsely long-hairy; leaves green, becoming glabrous |
| var. jacintensis |
| | 7' Corolla 10–12 mm, becoming glabrous; leaves canescent |
| var. rothrockii |
| | 5' Corolla (12)15–23 mm, tube + throat < upper lip |
| |
| | 8. Staminode densely hairy; corolla yellow; anther sacs 1.1–1.8 mm |
| K. antirrhinoides |
| | 9. Calyx 3–6 mm, lobes widely ovate, tips obtuse to acute; plant finely hairy; anther sacs 1.4–1.8 mm |
| var. antirrhinoides |
| | 9' Calyx 5.5–9 mm, lobes lanceolate, tips acute to acuminate; plant canescent; anther sacs 1.1–1.5 mm |
| var. microphylla |
| | 8' Staminode glabrous near tip; corolla white, cream, or rose-tinged; anther sacs 0.6–0.8 mm |
| K. breviflora |
| var. breviflora |
| var. glabrisepala
|