| 1. Ligules generally pink to purple or blue (rarely white) aliens of coast |
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| 2. Herbage sticky; main leaves deeply toothed or lobed |
| S. elegans |
| 2' Herbage not sticky; main leaves merely toothed |
| S. hybridus |
| 1' Ligules generally yellow (to brick-colored, rarely 0 or white) |
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| 3. Vine; leaves ivy-like; weedy |
| S. mikanioides |
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| 4. Subshrub or shrub (if weakly woody, branching aspect shrub-like); leaves or segments linear |
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| 5. Outermost phyllaries well developed, some 1/2 × main phyllaries |
| S. flaccidus |
| 6. Herbage ± gray-tomentose |
| var. douglasii |
| var. monoensis |
| 5' Outermost phyllaries 0 or inconspicuous herbage ± glabrous (except sometimes leaf lower surface or heads) |
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| 7. Leaves pinnately lobed, ± hairy below Channel Islands |
| S. lyonii |
| 7' Leaves generally linear, ± entire |
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| 8. Phyllaries ± 13; leaves ± thread-like, < 2 mm wide; coastal |
| S. blochmaniae |
| 8' Phyllaries ± 8; some leaves > 2 mm wide; e of High Sierra Nevada |
| S. spartioides |
| 4' Annual or perennial herb; leaves or segments wider than linear |
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| 9. Leaves ± equal, evenly distributed or crowded upward at flowering |
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| 10. Leaves generally 12-pinnately lobed; heads 2060; stems 1few, erect |
| S. jacobaea |
| 10' Leaves entire to lobed (if 2-pinnately lobed, heads < 20, stems ascending) |
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| 11. Annual from slender taproot |
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| 12. Ligules conspicuous, spreading |
| S. californicus |
| 12' Ligules 0 or small, often recurved or inrolled |
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| 13. Main leaves cordate-clasping, bases 12 cm wide; herbage glabrous |
| S. mohavensis |
| 13' Leaves petioled, little or not clasping; herbage glabrous or tomentose |
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| 14. Outermost phyllaries conspicuous, black-tipped; main phyllaries ± 21; herbage ± glabrous abundant weed |
| S. vulgaris |
| 14' Outermost phyllaries 0 or inconspicuous, green-tipped; herbage glabrous to tomentose |
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| 15. Main phyllaries generally ± 8, sometimes 13; plants generally < 2 dm; herbage generally glabrous; native |
| S. aphanactis |
| 15' Main phyllaries ± 13 or 21; plants generally 38 dm; herbage sparsely rough-tomentose; naturalized weed |
| S. sylvaticus |
| 11' Perennial from taproot, caudex, or rhizome |
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| 16. Plants generally < 2 dm, often spreading; alpine or subalpine |
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| 17. Leaves widely linear; plants rhizomed |
| S. pattersonensis |
| 17' Leaves ± ovate; plants taprooted |
| S. fremontii |
| 18. Phyllaries (6)810 mm; upper leaves well developed; High Cascade Range, Warner Mountains |
| var. fremontii |
| 18' Phyllaries 57(8) mm; upper leaves bract-like; Sierra Nevada, San Bernardino Mountains, East of Sierra Nevada |
| var. occidentalis |
| 16' Plants 5+ dm, erect; montane |
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| 19. Leaves pinnately lobed or dissected; herbage tomentose with jointed hairs or becoming ± glabrous |
| S. clarkianus |
| 19' Leaves dentate; herbage glabrous or sparsely tomentose below |
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| 20. Leaves ± linear-lanceolate, tapered |
| S. serra var. serra |
| 20' Leaves narrowly triangular, truncate or hastate |
| S. triangularis |
| 9' Leaves reduced upward; lower leaves prominent, generally persistent |
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| 21. Plant from button-like caudex; roots many, fleshy-fibrous, unbranched |
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| 22. Plants glabrous or minutely hairy among heads |
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| 23. Herbage glaucous; leaves fleshy; plants sometimes 1020 dm, tolerant of standing saltwater |
| S. hydrophilus |
| 23' Herbage not glaucous; leaves firm; plants < 10 dm, of damp soil but not standing water |
| S. hydrophiloides |
| 22' Plants hairy, sometimes becoming subglabrous |
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| 24. Ray flowers 0(2); disk flowers < 20; main phyllaries generally ± 8, sometimes 13; basal leaf margins wavy or shallow-toothed |
| S. aronicoides |
| 24' Ray flowers generally present; disk flowers 2050; main phyllaries generally ± 21, sometimes 13; basal leaves generally subentire |
| S. integerrimus |
| 25. Ligules off-white to cream-colored |
| var. ochroleucus |
| 25' Ligules yellow, rarely 0 |
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| 26. Main phyllaries 510 mm, lanceolate, often strongly black-tipped; ± hairy |
| var. exaltatus |
| 26' Main phyllaries 812 mm, ± linear, ± not black-tipped; densely hairy |
| var. major |
| 21' Plants from taproot, rhizome, or non-button-like caudex |
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| 27. Stems from thick, creeping or erect rhizome; roots fleshy, unbranched; leaves tapered to winged petiole, marginal teeth hard, translucent |
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| 28. Ray flowers 0; main phyllaries ± 21; disk corollas orange-yellow |
| S. astephanus |
| 28' Ray flowers present; main phyllaries ± 13; disk corollas yellow |
| S. scorzonella |
| 27' Stems from thin taproot, caudex, or rhizome; roots fibrous, branched; leaves subentire to pinnately divided, marginal teeth not hard, not translucent |
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| 29. Herbage (sub)glabrous; basal leaves entire to toothed |
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| 30. Ray flowers 0 (or inflorescence distinctly umbel-like) |
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| 31. Heads 820+; corollas yellow; leaves thin |
| S. indecorus |
| 31' Heads generally < 6; corollas deep yellow to brick-colored; leaves thick |
| S. pauciflorus |
| 30' Ray flowers present (or inflorescence cyme-like) |
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| 32. Head 1(3) plant from slender rhizome |
| S. cymbalarioides |
| 32' Heads generally 4many |
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| 33. Plants sparsely short-hairy at maturity |
| S. layneae |
| 33' Plants ± completely glabrous at maturity |
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| 34. Lower leaf bases cordate to truncate |
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| 35. Corollas orange-yellow to orange; basal leaves ± long as wide, rounded at tip |
| S. ganderi |
| 35' Corollas yellow; basal leaves widely lanceolate, blunt or pointed at tip |
| S. pseudaureus var. pseudaureus |
| 34' Lower leaf bases obtuse to tapered |
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| 36. Herbage glaucous; leaves ± entire; plants < 10 dm |
| S. clevelandii |
| 36' Herbage not glaucous; leaves subentire to toothed; plants generally < 4 dm |
| S. streptanthifolius |
| 29' Young herbage hairy (sometimes becoming subglabrous) or basal leaves pinnately lobed or divided |
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| 37. Basal leaves pinnately divided or lobed; herbage ± glabrous |
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| 38. Terminal lobe of lower leaves = or > lateral; lateral lobes 13 pairs |
| S. bolanderi var. bolanderi |
| 38' Terminal lobe of lower leaves < lateral (or lateral lobes > 6 pairs) |
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| 39. Heads small, main phyllaries generally 48 mm |
| S. multilobatus |
| 39' Heads large, main phyllaries generally 810 mm |
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| 40. Plants 410 dm; stems generally 1 from a short caudex; mid-cauline leaves ± prominent |
| S. breweri |
| 40' Plants 25(7) dm; stems often several from branched caudex; mid-cauline leaves reduced |
| S. eurycephalus |
| 41. Leaves irregularly lobed or dissected, lobes toothed; stems several but aspect not shrub-like |
| var. eurycephalus |
| 41' Leaves deeply and finely 12-dissected; aspect ± shrub-like |
| var. lewisrosei |
| 37' Basal leaves entire to dentate (or if pinnate, loosely tomentose) |
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| 43. Herbage permanently ± hairy; leaf margins flat; blade length 1.52 × width |
| S. canus |
| 43' Herbage ± glabrous at flowering; leaf margins often weakly rolled under; blade length > 2 × width |
| S. macounii |
| 42' Heads 1few (generally < 6) |
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| S. ionophyllus |
| 44' Leaves subentire or dentate |
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| 45. Disk 18+ mm diam, ligules orange to brick-colored |
| S. greenei |
| 45' Disk < 15 mm diam, ligules yellow |
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| 46. Cauline leaves gradually reduced, conspicuous |
| S. bernardinus |
| 46' Cauline leaves bract-like (plants ± scapose) |
| S. werneriifolius
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