| | 1. Perianth reddish purple, generally >> 18 mm; filaments fused ± in basal half; stem rounded, not winged (sect. Eriphilema) |
| S. douglasii var. douglasii |
| | 1' Perianth bluish, violet, yellow, or white, generally < 18 mm; filaments ± completely free or ± completely fused; stem ± flat, winged |
| |
| | 2. Perianth yellow; filaments ± completely free (sect. Echthronema) |
| |
| | 3. Stem generally >> 2 mm wide; perianth generally 11–18 mm |
| S. californicum |
| | 3' Stem generally < 2 mm wide; perianth generally 7–11 mm |
| S. elmeri |
| | 2' Perianth bluish to violet, rarely white, each part with a basal yellow blotch; filaments ± completely fused (sect. Sisyrinchium) |
| |
| | 4. Inner bract with ± uniformly narrow translucent margins; outer perianth parts generally elliptic to narrowly oblanceolate |
| S. idahoense |
| | 5. Upper stem margins generally with a few widely spaced, fine teeth; margins of outer bract fused in basal 4–7 mm; perianth generally >> 13 mm |
| var. idahoense |
| | 5' Upper stem margins generally entire; margins of outer bract fused generally < 4.5 mm; perianth generally < 13 mm |
| var. occidentale |
| | 4' Inner bract with translucent margins wider at or just below tip; outer perianth parts generally wedge-shaped |
| |
| | 6. Stem generally without leaf-bearing nodes — translucent margins of inner bract extending above tip as 2 rounded teeth; perianth generally medium blue to blue-violet, 9–12 mm, outer parts generally widely wedged-shaped; mostly East of Sierra Nevada |
| S. halophilum |
| | 6' Stems generally with 1 or more leaf-bearing nodes |
| |
| | 7. Translucent margins of inner bract not extending above tip; perianth deep bluish purple to blue-violet, or pale blue, rarely white, 10.5–17 mm, outer parts generally widely wedge-shaped; California, Oregon |
| S. bellum |
| | 7' Translucent margins of inner bract extending above tip as 2 rounded teeth; perianth generally pale blue, 10–15 mm, outer parts generally narrowly wedge-shaped; ne Mojave Desert |
| S. funereum
|