| 1. Corolla cylindric, << 3 mm; flowers generally cleistogamous; bracts ovate |
| G. tenella |
| 1' Corolla funnel- to bell-shaped, generally > 3.5 mm; flowers not cleistogamous; bracts narrower than ovate |
| |
| 2. Corolla showy, 11.5 × longer than wide; filament base wide, ciliate |
| G. pulchella |
| 3. Ovary 35.5 mm; corolla generally < 12 mm |
| subsp. serpentinicola |
| 3' Ovary > 5.5 mm; corolla generally > 12 mm |
| |
| 4. Ovary obconic, with dense, recurved, stiff hairs; upper branches 1530 mm |
| subsp. campestris |
| 4' Ovary cylindric to narrowly obconic, ± glabrous to finely hairy; upper branches > 32 mm |
| subsp. pulchella |
| 2' Corolla inconspicuous, 24.5 × longer than wide at level of sinuses; filament base narrow, glabrous or sparsely ciliate |
| |
| 5. Ovary obconic, top slightly narrowed, base long-tapered; pedicel rarely 0; corolla 4.514 mm |
| G. specularioides |
| 5' Ovary cylindric to obconic, narrowed near middle, base swollen; pedicel 0; corolla 1.57.5 mm |
| G. diffusa |
| 6. Corolla lobes white, pale blue, or pink, becoming darker in drying |
| |
| 7. Upper stem 0.41 mm wide; corolla 57.5 mm |
| subsp. candida |
| 7' Upper stem 0.20.4 mm wide; corolla 1.55 mm |
| subsp. filicaulis |
| 6' Corolla lobes light violet, violet-blue, or deep blue |
| |
| 8. Ovary 56.5 × longer than wide at top |
| subsp. diffusa |
| 8' Ovary 25 × longer than wide at top |
| subsp. robusta
|