| | 1. Pappus present; heads open at midday; annual or perennial herb |
| |
| | 2. Perennial; leaves opposite well up stem; rosette leaves widest |
| |
| | 3. Phyllaries 10–12 mm; anthers black; disk flowers fertile; ray achenes beakless |
| M. bolanderi |
| | 3' Phyllaries 5–6 mm; anthers yellow; disk flowers staminate; ray achenes often short-beaked |
| M. madioides |
| | 2' Annual; leaves mostly alternate; rosette leaves narrow |
| |
| | 4. Ray achenes bowed outward, short-beaked; disk flowers staminate |
| |
| | 5. Anthers yellow; Klamath Ranges |
| M. doris-nilesiae |
| | 5' Anthers brown to black; Sierra Nevada |
| |
| | 6. Ray flowers 15–20, corolla 5–9 mm; disk pappus purplish |
| M. rammii |
| | 6' Ray flowers 2–8, corolla 2.5–3 mm; disk pappus not purplish |
| M. yosemitana |
| | 4' Ray achenes club-shaped (slightly bowed outward or not), beakless; some or all disk flowers fertile — s North Coast Ranges, n San Francisco Bay Area |
| |
| | 7. Disk pappus scales 0.2–0.5 mm |
| M. hallii |
| | 7' Disk pappus scales 1.2–3.7 mm |
| |
| | 8. Heads nodding in bud and fruit; disk flowers fertile; pappus scales fringed, not plumose |
| M. nutans |
| | 8' Heads generally erect; central disk flowers staminate; pappus scales plumose |
| M. stebbinsii |
| | 1' Pappus 0; heads often closing by midday; annual |
| |
| | 9. Disk flowers 1–2, corollas glabrous; phyllary tips not flat; stems thread-like |
| |
| | 10. Ray achenes compressed side-to-side, sharply angled; involucre prominently yellow-glandular |
| M. exigua |
| | 10' Ray achenes compressed front-to-back, not angled; involucre minutely black-glandular |
| M. minima |
| | 9' Disk flowers generally 2–many, corollas puberulent; phyllary tips ± flat; stems not thread-like |
| |
| | 11. Ray achenes with short, off-center beak; chaff scales deciduous; heads open at midday |
| M. radiata |
| | 11' Ray achenes with beak minute or 0; chaff scales persistent; heads generally closing by midday |
| |
| | 12. Disk flowers staminate, not forming fruits; receptacle hairy; rays flowers often very conspicuous |
| |
| | 13. Ray achenes barely compressed, ± triangular with wide backs; ligules inconspicuous |
| |
| | 14. Ligules greenish yellow; anthers black; herbage lemon-scented |
| M. citriodora |
| | 14' Ligules bright yellow; anthers yellow; herbage not lemon-scented |
| M. elegans subsp. wheeleri |
| | 13' Ray achenes strongly compressed, with narrow backs; ligules generally conspicuous |
| M. elegans |
| | 15. Basal rosette well developed; stems stout, very leafy below, heavily glandular; phyllary tips = or > body; flower summer to autumn |
| subsp. densifolia |
| | 15' Basal rosette weakly developed or 0; stems slender to ± stout, leaves crowded or well separated, moderately to heavily glandular; phyllary tips generally = body; flower spring or summer |
| |
| | 16. Herbage soft-hairy below, ± densely glandular above; generally > 1000 m; flower summer |
| subsp. elegans |
| | 16' Herbage sparsely hairy to densely bristly, barely glandular or not below inflorescence; generally < 1000 m; flower spring |
| subsp. vernalis |
| | 12' Disk flowers fertile, forming fruits; receptacle glabrous; ray flowers generally inconspicuous |
| |
| | 17. Ray flowers 0–3; ray achenes widest at middle, ends truncate |
| M. glomerata |
| | 17' Ray flowers 3–9(14); ray achenes widest toward top, tapered to base |
| |
| | 18. Fruits obovoid, plump, black, shiny |
| M. anomala |
| | 18' Fruits compressed side-to-side, dull |
| |
| | 19. Plants strongly glandular throughout; stems stout; involucre 7–15 mm |
| M. sativa |
| | 19' Plants generally glandular only above middle; stems often slender; involucre generally < or = 10 mm |
| |
| | 20. Heads subsessile or short-peduncled, in dense spike- or raceme-like clusters |
| |
| | 21. Herbage dark green; involucre 6–10 mm; widespread |
| M. gracilis |
| | 21' Herbage yellow-green; involucre 6–7 mm; Sierra Nevada Foothills |
| M. subspicata |
| | 20' Heads slender-peduncled, in open raceme- or panicle-like clusters |
| |
| | 22. Branches > main stem; cauline leaves widest at base; herbage densely ± appressed-soft-hairy |
| M. citrigracilis |
| | 22' Branches < main stem; cauline leaves narrow at base; herbage coarsely spreading-hairy |
| M. gracilis
|