| | 1. Awn exserted beyond glume tips 1–10 mm, twisted and bent |
| |
| | 2. Panicle open, branches spreading to ascending |
| |
| | 3. Plant from rhizomes; stem > 4 dm; leaf blades generally cauline, 3–10 mm wide; coastal, < 100 m |
| C. bolanderi |
| | 3' Plant cespitose, rhizomes 0; stem generally < 3 dm; leaf blades generally basal, 1–2 mm wide; subalpine to alpine, > 1300 m |
| C. breweri |
| | 2' Panicle dense, narrow, branches ascending to appressed |
| |
| | 4. Awn exserted 2–5+ mm beyond glume tips |
| |
| | 5. Glumes 8–10 mm, long-acuminate; awn exserted 5+ mm beyond glume tips |
| C. foliosa |
| | 5' Glumes 4.5–8 mm, acute to acuminate; awn exserted 2–4 mm beyond glume tips |
| C. purpurascens |
| | 4' Awn exserted < 1 mm beyond glume tips or sides |
| |
| | 6. Glumes 6.5–8 mm — serpentine soils |
| 2 C. ophitidis |
| |
| 2 C. koelerioides |
| | 7' Collar puberulent to short-hairy |
| 2 C. rubescens |
| | 1' Awn generally < glumes, sometimes prolonged beyond glume tips < 1 mm, straight or twisted and bent |
| |
| | 8. Inflorescence ± open, lower branches spreading to ascending |
| |
| | 9. Callus hairs dense, length > 1/2 lemma; glumes 3–4.5 mm; awn generally slender, ± flexible, straight or slightly twisted |
| C. canadensis |
| | 9' Callus hairs sparse, length < 1/4 lemma; glumes 5–7+ mm; awn stiff, generally twisted |
| C. nutkaensis |
| | 8' Inflorescence ± dense, narrow, lower branches appressed (sometimes ascending in C. stricta) |
| |
| | 10. Callus hair length > 1/2 lemma; awn generally straight; glumes 2–6 mm |
| C. stricta |
| | 11. Glumes thick, margin generally opaque; blade 3–6 mm wide; ligule 2–6 mm |
| subsp. inexpansa |
| | 11' Glumes thin, margin ± translucent; blade 2–4 mm wide, generally inrolled; ligule 1–3 mm |
| subsp. stricta |
| | 10' Callus hair length < 1/2 lemma; awn generally twisted, bent; glumes > 4 mm |
| |
| | 12. Glumes 6.5–8 mm — serpentine soils |
| 2 C. ophitidis |
| |
| 2 C. koelerioides |
| | 13' Collar puberulent to short-hairy |
| 2 C. rubescens
|