| | 1. Involucral bracts and awns (or ribs) 3–5 |
| |
| | 2. Involucral bracts and awns 3 |
| |
| | 3. Involucral tube cylindric, prominently cross-ridged, glabrous; stamens 6; Desert |
| C. corrugata |
| | 3' Involucral tube 3-angled, ± bell-shaped or flaring, smooth to moderately cross-ridged, hairy; stamens 9; Southwestern California, East of Sierra Nevada, Desert |
| |
| | 4. Plant erect; awns of inflorescence and involucral bracts straight — East of Sierra Nevada, Desert |
| C. rigida |
| | 4' Plant prostrate to decumbent; inflorescence bracts unawned, involucral awns hooked |
| |
| | 5. Involucral tube very narrowly flaring, smooth, ± brown; South Coast |
| C. orcuttiana |
| | 5' Involucral tube bell-shaped, thinly hairy, reddish; Peninsular Ranges |
| 2 C. polygonoides var. longispina |
| | 2' Involucral bracts and awns 4–5 |
| |
| | 6. Awns straight; perianth 2.5–3.5 mm, glabrous; stamens attached at base of perianth tube; Mojave Desert |
| C. spinosa |
| | 6' Awns hooked; perianth 1.5–2.5 mm, hairy; stamens attached near top of perianth tube |
| |
| | 7. Involucral tube cylindric, 3–4.5 mm, largest bract ± leaf-like; perianth yellow, thinly hairy; Great Basin Floristic Province, Mojave Desert, n Western Transverse Ranges |
| C. watsonii |
| | 7' Involucral tube bell-shaped, 1.5–2.5 mm, bracts not leaf-like; perianth white to rose, densely hairy; California Floristic Province |
| C. polygonoides |
| | 8. Involucre (including awn) 3–4 mm; Peninsular Ranges |
| var. longispina |
| | 8' Involucre (including awn) ± 5 mm; n California |
| var. polygonoides |
| | 1' Involucral bracts and awns (or ribs) 6 |
| |
| | 9. Involucral bract margin scarious or membranous |
| |
| | 10. Involucral bract margin membranous, continuous across sinuses (involucre thus mimicking a fused corolla); true cauline leaves (no inflorescence or involucre in axil) generally present; generally inland California Floristic Province |
| |
| | 11. Cauline leaves (and lower bracts) alternate; involucre ± woolly or becoming glabrous, bracts ± equal; perianth 1.5–3 mm, densely hairy — California Floristic Province |
| C. membranacea |
| | 11' Whorl of true cauline leaves present near mid-stem in most plants; involucre bristly, bracts equal or not; perianth 3.5–5 mm, sparsely hairy |
| |
| | 12. 3 involucral bracts >> alternating 3, membrane purple; South Coast Ranges |
| C. douglasii |
| | 12' 6 involucral bracts ± equal, membrane white; foothills around n&e Great Central Valley |
| 2 C. stellulata |
| | 10' Involucral bract margin scarious, not continuous across sinuses (except sometimes between pairs of erect bracts); true cauline leaves generally 0; ± coastal Central Western California, North Coast (except C. stellulata) (C. pungens complex) |
| |
| | 13. Involucral awns straight |
| |
| | 14. Plant generally decumbent; involucral bracts spreading, awns brown; perianth 3–4.5 mm; c North Coast |
| C. howellii |
| | 14' Plant generally ± erect; involucral bracts erect, awns ivory or straw-colored; perianth 4–6 mm; n Central Coast |
| 2 C. valida |
| | 13' Involucral awns hooked |
| |
| | 15. Perianth glabrous, lobes white, tube yellow |
| C. diffusa |
| | 15' Perianth hairy, lobes same color as tube |
| |
| | 16. Plant generally erect; whorl of true cauline leaves often present; involucral tube 3–4 mm, bracts clearly margined |
| |
| | 17. Plant decumbent to erect, soft-hairy; involucre thinly hairy; perianth 2.5–4 mm; n Central Coast, s San Francisco Bay Area |
| C. robusta |
| | 17' Plant strictly erect, coarse-hairy; involucre bristly; perianth 4–5 mm; foothills around n Great Central Valley |
| 2 C. stellulata |
| | 16' Plant prostrate to ascending; cauline leaves 0; involucral tube 1.5–3 mm, bract margins sometimes indistinct |
| |
| | 18. Involucral bracts obviously white- to purple-margined, tube 2–3 mm; stamens 9 |
| C. pungens |
| | 18' Involucral bract margins thin, ± indistinct; involucral tube 1.5–2.5 mm; stamens 3–9 |
| |
| | 19. Perianth lobes barely exserted, entire to jagged (central tooth, if any, generally not greatly predominant); stamens 3–9; s Central Coast |
| 2 C. angustifolia |
| | 19' Perianth lobes well exserted, with an abrupt central tooth (if teeth > 1, central greatly predominant); stamens 9; n Central Coast, San Francisco Bay Area |
| 2 C. cuspidata |
| | 9' Involucral bract margin not scarious or membranous |
| |
| | 20. Involucral awns unequal, longest generally > 2 × length of next longest in some or all involucres |
| |
| | 21. Longest involucral awn hooked, ± 2 × length of next longest — Northwestern California, Central Western California, s Sierra Nevada |
| C. clevelandii |
| | 21' Longest involucral awn straight, generally 3–5 × length of next longest |
| |
| | 22. Longest involucral awn ± 5 × length of next longest — eastern Central Western California, s Sierra Nevada, n Western Transverse Ranges |
| C. uniaristata |
| | 22' Longest involucral awn ± 3 × length of next longest |
| |
| | 23. Involucres (including awns) generally 5–7 mm, scattered in small clusters; Outer South Coast Ranges |
| C. rectispina |
| | 23' Involucres generally 8–10 mm, clumped in large clusters; Inner South Coast Ranges |
| C. ventricosa |
| | 20' Involucral awns equal or of alternating lengths, longest generally < 2 × length of next longest |
| |
| | 24. Inner perianth lobes either rather deeply fringed or notched (may require dissection of involucre to see) |
| |
| | 25. Outer perianth lobes fringed along sides; Southwestern California |
| C. fimbriata |
| | 26. Fringe segments, especially lobe tip, wide, ± lobe-like; s South Coast, w Peninsular Ranges |
| var. fimbriata |
| | 26' Fringe segments, including lobe tip, thin, not lobe-like; e Peninsular Ranges |
| var. laciniata |
| | 25' Outer perianth lobes entire or tip notched or fringed; South Coast Ranges (C. palmeri complex) |
| |
| | 27. Perianth lobes white to pinkish |
| |
| | 28. Inner perianth lobes notched, 5–6 mm; plant yellowish green; Western Transverse Ranges (Sierra Madre Mtns, Santa Barbara Co.) |
| C. blakleyi |
| | 28' Inner perianth lobes fringed, 4–5 mm; plant reddish or greenish; Outer South Coast Ranges |
| C. obovata |
| | 27' Perianth lobes red to purple |
| |
| | 29. Outer perianth lobes entire, erect; on serpentine; Outer South Coast Ranges |
| C. palmeri |
| | 29' Outer perianth lobes ± notched, spreading to recurved; not on serpentine; South Coast Ranges |
| C. biloba |
| | 30. Outer perianth lobes deeply notched; South Coast Ranges |
| var. biloba |
| | 30' Outer perianth lobes shallowly notched; Inner South Coast Ranges |
| var. immemora |
| | 24' Inner perianth lobes entire, with a central tooth, or shallowly jagged (may require dissection to see) |
| |
| | 31. Perianth lobes all equal in length and width |
| |
| | 32. Plant erect; inflorescence breaking at nodes; stamens 3, attached near top of perianth tube |
| C. brevicornu |
| | 33. Leaves ± linear; generally Desert |
| var. brevicornu |
| | 33' Leaves oblanceolate; East of Sierra Nevada |
| var. spathulata |
| | 32' Plant prostrate to decumbent; inflorescence not breaking at nodes; stamens 3–9, attached at base of perianth tube; w California Floristic Province |
| |
| | 34. Perianth lobes entire; plant thinly hairy, yellowish green when fresh; filaments fused at base; Southwestern California |
| C. procumbens |
| | 34' Perianth lobes ± jagged or with a central tooth; plant densely hairy, brown or gray; filaments free; Central Coast |
| |
| | 35. Perianth lobes barely exserted, entire to jagged (central tooth, if any, generally not greatly predominant); stamens 6–9; s Central Coast |
| 2 C. angustifolia |
| | 35' Perianth lobes well exserted, with an abrupt central tooth (if teeth > 1, central greatly predominant); stamens 9; n Central Coast, San Francisco Bay Area |
| 2 C. cuspidata |
| | 31' Perianth lobes unequal, inner generally < and narrow than outer |
| |
| | 36. Most involucral awns straight; perianth lobes sometimes ± jagged at tip |
| |
| | 37. Plant decumbent; involucre 1.5–2 mm, bracts spreading; South Coast |
| C. parryi var. fernandina |
| | 37' Plant ± erect; involucral tube 3–4.5 mm, bracts erect; s North Coast |
| 2 C. valida |
| | 36' Involucral awns hooked; perianth lobes generally entire |
| |
| | 38. Plant grayish, canescent; involucral tube 1.5–2 mm — Transverse Ranges |
| C. parryi var. parryi |
| | 38' Plant reddish or greenish, thinly hairy; involucral tube 2.5–6 mm (C. staticoides complex) |
| |
| | 39. Lower bracts ± linear, not very leaf-like, deciduous |
| |
| | 40. Perianth well exserted; involucres loosely clustered; eastern Peninsular Ranges |
| C. leptotheca |
| | 40' Perianth moderately exserted; involucres densely clustered; s Central Western California, Southwestern California |
| C. staticoides |
| | 39' Lower bracts ± oblanceolate, ± leaf-like, persistent |
| |
| | 41. Involucral tube 3.5–5 mm, cylindric; not on serpentine |
| C. xanti |
| | 42. Involucre densely hairy; eastern San Bernardino Mountains, n San Jacinto Mountains |
| var. leucotheca |
| | 42' Involucre thinly hairy; s Sierra Nevada Foothills, Inner South Coast Ranges, n border Transverse Ranges, East of Sierra Nevada |
| var. xanti |
| | 41' Involucral tube generally 2–3 mm, ± bell-shaped; on serpentine or not |
| |
| | 43. Inflorescence clusters ± open; involucral tube generally 2.5–3 mm; stamens 9; serpentine; s Outer South Coast Ranges |
| C. breweri |
| | 43' Inflorescence clusters head-like; involucral tube generally 2-2.5 mm; stamens 6; non-serpentine; n Channel Islands |
| C. wheeleri
|