| 1. Calyx > 12 mm; corolla white to rose or red-orange, lobes 1/51/2 tube; perennial herb |
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| 2. Corolla 3545 mm, red-orange to yellow, tube funnel-shaped, 1.53 mm wide at top, lobes ascending; calyx 2025 mm; anthers 1.21.5 mm |
| M. macrantha |
| 3. Stem hairy; leaf triangular-ovate, sparsely to densely hairy, ciliate |
| subsp. hallii |
| 3' Stem glabrous to sparsely hairy; leaf elliptic to ovate, ± glabrous, not ciliate |
| subsp. macrantha |
| 2' Corolla 1530 mm, white to cream-yellow or rose-tinged, tube cylindric, 0.51.5 mm wide at top, lobes spreading; calyx 1220 mm; anthers < 1 mm |
| M. nana |
| 4. Corolla tube ± 11.5 mm wide at top; leaf generally > 10 mm, green, glabrous to sparsely spreading-hairy |
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| 5. Corolla cream-yellow, tube 1.52 × calyx, lobes 710 mm |
| subsp. leptosiphon |
| 5' Corolla white, tube 1.251.5 × calyx, lobes 67 mm |
| subsp. nana |
| 4' Corolla tube ± 0.51 mm wide; leaf generally 515 mm, ash-gray, densely ± appressed-puberulent |
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| 6. Calyx hairs ± dense, generally > 1 mm, wavy |
| subsp. arida |
| 6' Calyx hairs ± sparse, generally < 1 mm, straight |
| subsp. tenuiflora |
| 1' Calyx < 12 mm; corolla white to straw or purple, lobes > 1/2 tube; annual, perennial herb |
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| 7. Leaf margin wavy, generally ± entire (less often ± serrate) |
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| 8. Leaf < 10 mm, narrowly ovate to triangular-ovate; subalpine forests; s High Sierra Nevada |
| M. beneolens |
| 8' Leaf > 10 mm, linear to ovate; dunes, scrub; Central Coast, San Francisco Bay Area |
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| 9. Annual; stem glabrous or sparsely hairy |
| M. undulata |
| 9' Perennial; stem sparsely hairy to densely tomentose |
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| 10. Stem densely white-tomentose; head 2030 mm wide; middle bracts 715 mm; leaf oblanceolate to ovate, fleshy, appearing glaucous |
| M. crispa |
| 10' Stem purple, ± sparsely hairy; head 1020 mm wide; middle bracts 710 mm; leaf linear to narrowly lanceolate, thin, green |
| M. frutescens |
| 7' Leaf margin faintly or not wavy, entire to serrate |
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| 11. Annual; heads severalmany per main stem, arrayed in panicles |
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| 12. Bract lateral veins ± perpendicular to midvein, areas between veins silvery-translucent |
| M. douglasii |
| 13. Stem slender; head 1015 mm wide; bracts 1015 mm, narrowly ovate |
| subsp. douglasii |
| 13' Stem stout; head 2030 mm wide; bracts 1530 mm, widely ovate |
| subsp. venosa |
| 12' Bract lateral veins ± parallel to midvein, areas between veins leaf-like, membranous, or scarious but not silvery |
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| 14. Bracts not white; calyx lobes not white; corolla rose or purple, rarely white |
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| M. pringlei |
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| 16. Bracts acuminate, not cross-veined; calyx 1415-veined |
| M. breweri |
| 16' Bracts acute, cross-veined; calyx 13-veined |
| M. lanceolata |
| 14' Bracts at least partly white; calyx lobes or lobe tips or margins white; corolla generally or mostly white |
| |
| 17. Calyx lobe tips awl-like, recurved; bracts white throughout; stamens included |
| M. leucocephala |
| 17' Calyx lobe tips acute, erect; bracts partly white; stamens slightly exserted |
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| 18. Main stem 1° branches above middle; bracts ovate, cross-veined; Sierra Nevada Foothills |
| M. candicans |
| 18' Main stem 1° branches generally below middle; bracts generally narrowly ovate, not cross-veined; s San Joaquin Valley, Mojave Desert |
| M. exilis |
| 11' Perennial; heads generally 1 per main stem (or few, arrayed in spikes or racemes in M. follettii, M. robisonii, M. siskiyouensis, M. stebbinsii) |
| |
| 19. Middle bracts like leaves in texture and hairiness, greenish, generally reflexed (innermost of middle series sometimes ± scarious) lower leaf surface glandular-hairy |
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| 20. Leaf narrowly to widely ovate, soft-hairy, wavy-hairy, or woolly (hairs generally > 0.5 mm except subsp. obispoensis), lower surface woolly or not |
| M. villosa |
| 21. Leaf ovate to widely triangular-ovate, base generally truncate; stem generally densely matted-woolly (or ± glabrous) |
| subsp. franciscana |
| 21' Leaf ± narrowly ovate, base tapered to obtuse; stem generally sparsely to densely spreading-hairy (or ± glabrous) |
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| 22. Some hairs branched; old plants tufted to matted; corolla white to lavender |
| subsp. obispoensis |
| 22' Hairs unbranched; plants matted or not; corolla pink to purple |
| |
| 23. Plant > 50 cm; leaf blade 2250 mm; head 2040 mm wide; outer bracts 2030 mm |
| subsp. globosa |
| 23' Plant < 50 cm; leaf blade 1022 mm; head 1030 mm wide; outer bracts 820 mm |
| subsp. villosa |
| 20' Leaf lanceolate to narrowly ovate, glabrous, canescent, or stiff-hairy (hairs generally < 0.5 mm), lower surface not woolly |
| |
| 24. Plant sparsely to densely appressed- to spreading-hairy, whitish; head generally < 15 mm wide; middle bracts erect, in cup-like involucre |
| M. antonina |
| 25. Plant open, generally > 60 cm; leaf greenish, not folded; hairs appressed to ascending, short, often sparse, not hiding glands of stem and calyx |
| subsp. antonina |
| 25' Plant tufted, generally < 60 cm; leaf whitish, often folded; hairs spreading, long, generally dense, hiding glands of stem and calyx |
| subsp. benitensis |
| 24' Plant glabrous to densely and minutely canescent, green to ash-gray; head 1030 mm wide; middle bract tips recurved |
| |
| 26. Inner bracts 2many; plant glabrous to densely and minutely canescent |
| M. sheltonii |
| 26' Inner bracts 0; plant densely and minutely canescent |
| M. siskiyouensis |
| 19' Middle bracts generally not like leaves in either texture or hairiness, papery to leathery, greenish to white, straw, or purple, erect or spreading (outermost of middle series sometime like leaves, at least at tips) |
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| 27. Outer bracts present or 0; middle bracts scarious or papery, elliptic to ovate, erect, in cup-like involucre (not always apparent on pressed material) |
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| 28. Outer bract series present; middle bracts scarious or membranous, greenish to rose, sometime ± purple-tinged |
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| 29. Middle bracts long-acuminate, rose (or scarious and rose-tinged); calyx lobes hairy; corolla rose; Transverse Ranges |
| M. australis |
| 29' Middle bracts acute to obtuse, scarious, greenish, lavender- to rose- to purple-tinged or not; calyx lobes woolly; corolla white to purple; n California Floristic Province, Great Basin Floristic Province |
| M. odoratissima |
| 30. Outer bracts spreading, generally < 25 mm; corolla generally purple, less often lavender or white |
| subsp. odoratissima |
| 30' Outer bracts reflexed, generally 2540 mm; corolla generally white, sometimes ± purple-tinged |
| subsp. pallida |
| 28' Outer bract series 0; middle bracts papery, whitish to straw or purple, sometimed rose- or purple-tinged, less often grayish |
| |
| 31. Stem green, dark gray, or appearing glaucous; leaf elliptic, narrowly ovate, or ovate; n California |
| M. glauca |
| 31' Stem silvery to ash-gray with densely matted hairs; leaf linear to narrowly ovate; s California |
| M. linoides |
| 32. Leaf silvery or ash-gray; s High Sierra Nevada, Tehachapi Mountain Area, eastern San Bernardino Mountains, San Jacinto Mountains, East of Sierra Nevada, Desert Mountains |
| |
| 33. Leaf linear, oblong, or lanceolate, 1040 mm; bracts = or > calyces |
| subsp. linoides |
| 33' Leaf narrowly ovate, 1015 mm; bracts > calyces |
| subsp. oblonga |
| 32' Leaf greenish or appearing glaucous; San Gabriel Mountains, San Bernardino Mountains, Peninsular Ranges |
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| 34. Leaf generally 1020 mm; plant rhizomed; bracts obscurely gland-dotted; San Gabriel Mountains, San Bernardino Mountains |
| subsp. stricta |
| 34' Leaf 2040 mm; plant taprooted; bracts conspicuously gland-dotted; s Peninsular Ranges (San Diego Co.) |
| subsp. viminea |
| 27' Outer bracts present; middle bracts firm, leathery or scarious, lanceolate to ovate, reflexed to ascending, generally not in cup-like involucre |
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| 35. Leaves and lower stem ± glabrous |
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| 36. Bracts and calyces conspicuously gland-dotted; head generally < 15 mm wide; bracts lanceolate or narrowly ovate |
| M. follettii |
| 36' Bracts and calyces obscurely gland-dotted; head generally > 15 mm wide; bracts narrowly ovate to ovate |
| |
| 37. Corolla lobes < 1/2 tube; calyx 912 mm |
| M. palmeri |
| 37' Corolla lobes > 1/2 tube; calyx 68 mm |
| M. purpurea |
| 35' Leaves and stem hairy |
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| 38. Leaf surfaces both greenish or ash- to dark gray, purple blotched or not, sparsely to densely hairy; heads 1several per main stem; Sierra Nevada, Transverse Ranges, Desert Mountains |
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| 39. Upper stem hairs dense, felt-like |
| M. stebbinsii |
| 39' Upper stem hairs sparse to dense but not felt-like |
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| 40. Leaf 510 mm, generally few-toothed; head 1 per main stem; plant matted or tufted; s Outer South Coast Ranges?, eastern San Gabriel Mountains, San Jacinto Mountains? |
| M. cinerea |
| 40' Leaf 1040 mm, entire; heads generally several per main stem; plant open; Desert Mountains |
| M. robisonii |
| 38' Leaf surfaces unequally colored, lower surface ± white- or ash-gray-canescent, felt-like, or woolly, upper surface greener, hairs 0 to dense; heads generally 1 per main stem; s Inner North Coast Ranges, South Coast, Outer South Coast Ranges, Transverse Ranges, Peninsular Ranges |
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| 41. Leaf thick, lower surface felt-like or woolly; corolla white to pale lavender |
| M. hypoleuca |
| 42. Stem hairs 0 to sparse; leaf narrowly ovate, ± flat between rolled-under margins |
| subsp. hypoleuca |
| 42' Stem hairs ± dense; leaf linear-lanceolate, ± arched between rolled-under margins |
| subsp. lanata |
| 41' Leaf thin, lower surface canescent; corolla lavender, rose, or purple |
| M. viridis |
| 43. Head > 20 mm wide; bracts generally 1020 mm; San Gabriel Mountains |
| subsp. saxicola |
| 43' Head 1015(21) mm wide; bracts generally 610 mm; s Inner North Coast Ranges |
| subsp. viridis
|