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Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.

 

CEANOTHUS CALIFORNIA-LILAC

Dieter H. Wilken


Shrub, tree-like or not, generally erect or mat- to mound-like. Stem: branches generally arranged like leaves; twigs thorn-like or not, generally not angled. Leaf: alternate or opposite, some clustered on short-shoots or not, deciduous or evergreen; stipules scale-like, thin, deciduous, or knob-like, corky, thick, base persistent; blade flat or wavy, tip generally acute to obtuse, margin thick (i.e., thicker than adjacent blade) or not, rolled under or not, wavy or not, entire or gland- or sharp-toothed, glands generally dark, teeth pale, alternate blade 1–3-ribbed from base, generally thin, opposite blade 1-ribbed from base, thick, firm. Inflorescence: umbel-, raceme-, or panicle-like aggregations of few-flowered clusters, axillary or terminal; pedicels white to deep blue or pink. Flower: conspicuous, generally < 5 mm; hypanthium surrounding fleshy disk below ovary base, in fruit thick, not splitting; sepals generally 5, lance-deltate, incurved, colored like petals, persistent; petals generally 5, blade hood-like, white to deep blue or pink; stamens generally 5, opposite petals; ovary 1/2-inferior, 3-lobed, chambers 3, each 1-ovuled, styles 3. Fruit: capsule, ± spheric, generally ± 3-lobed, generally smooth, 3-ridged or not, horned or not. Seed: 3, 2–5 mm.
± 55 species: North America. (Greek: thorny plant) [Fross & Wilken 2006 Ceanothus. Timber Press] Hybrids common (named hybrids not recognized here), discussed in Fross & Wilken; hybrid forms do not key easily. As recircumscribed here, Ceanothus greggii A. Gray restricted to Mexico.

Key to Ceanothus

1. Stipules knob-like, corky, thick, bases persistent; leaves generally opposite (generally alternate in Ceanothus megacarpus var. megacarpus, Ceanothus verrucosus), clustered or not; inflorescence generally umbel-like (subg. Cerastes)

2. Leaves generally alternate

3. Leaf blade 10–25 mm, 5–12 mm wide, length generally > 2 × width, elliptic to widely oblanceolate, margin entire; fruit 7–12 mm wide ..... C. megacarpus var. megacarpus

3' Leaf blade 5–14 mm, 3–10 mm wide, length generally < 2 × width, widely obovate to round, margin entire or teeth ± sharp; fruit 4–6 mm wide ..... C. verrucosus

2' Leaves generally opposite, occasionally clustered

4. Plant mat- to mound-like, generally < 1 m; stems spreading, ± ascending, occasionally arched, rooting at nodes or not

5. Leaf margin generally entire, occasionally ± 3–5-toothed distally

6. Leaf blade 8–20 mm, gray-tomentose abaxially, margin thick or ± rolled under; Central Coast (nw San Luis Obispo Co.), < 60 m ..... C. maritimus

6' Leaf blade generally 4–12 mm, ± glabrous to strigose abaxially, margin not thick, ± not rolled under; Klamath Ranges, n North Coast Ranges, n&c Sierra Nevada, > 260 m

7. Leaves generally clustered, generally erect ..... C. roderickii (2)

7' Leaves ± evenly spaced, generally not clustered, spreading to ascending

8. Plant generally mound-like, generally 0.3–1 m, stems not rooting at nodes; twigs brown to gray-brown ..... C. arcuatus

8' Plant mat-like, < 0.3 m, stems rooting at nodes; twigs generally red-brown ..... C. fresnensis

5' Leaf blade margin 2–35-toothed

9. Leaf blade generally wide-elliptic or -obovate or round, length generally < 2 × width;, margin 5–35-toothed

10. Twigs generally not angled; flowers white to pale blue or blue-lavender

11. Leaf blade 10–20 mm; fruit 6–9 mm wide; horns 1–2 mm, wrinkled; Klamath Ranges (Trinity Mtns), s High Sierra Nevada (Kern Plateau), 1050–2750 m ..... C. pinetorum

11' Leaf blade 4–10 mm; fruit 4–6 mm wide; horns < 1 mm, smooth; Central Coast, < 400 m ..... C. rigidus (2)

10' Twigs generally angled distally; flowers blue to blue-purple ..... C. gloriosus

12. Plant < 0.3 m; stems generally spreading; leaf blade 23–31 mm, margin 13–35-toothed ..... var. gloriosus

12' Plant < 0.5 m; stems spreading to ± ascending; leaf blade 10–21 mm, margin 9–19-toothed ..... var. porrectus

9' Leaf blade generally elliptic to obovate or oblanceolate, length generally > 2 × width; margin 2–11-toothed

13. Leaf blade 2–6 mm wide, margin 0–5-toothed distally

14. Leaves not clustered, spreading, tips generally truncate, margin generally 2–3-toothed; Klamath Ranges, North Coast Ranges ..... C. pumilus

14' Leaves generally clustered, generally erect, tips obtuse to ± notched, margin 0–5-toothed; n Sierra Nevada Foothills (w El Dorado Co.) ..... C. roderickii (2)

13' Leaf blade 4–16 mm wide, margin generally 2–11-toothed distally

15. Leaf blade generally not ± wavy, generally not ± folded lengthwise; fruit 6–9 mm wide, horns 1–2 mm, thick, wrinkled (slender in Ceanothus prostratus var. occidentalis) ..... C. prostratus

16. Plant mound-like; leaf blade ± folded lengthwise, concave adaxially, teeth 5–9, in distal 1/2; fruit horns spreading ..... var. occidentalis

16' Plant generally mat-like; leaf blade ± not folded lengthwise, not concave adaxially, teeth 3–5(7), in distal 2/3; fruit horns erect ..... var. prostratus

15' Leaf blade generally ± wavy or ± folded; fruit 4–6 mm wide, horns 1.5–2.5 mm, ± slender, smooth

17. Plant mound-like, 0.2–0.5 m, stems spreading to ± ascending, occasionally rooting at nodes ..... C. confusus

17' Plant erect to mound-like, 0.5–1.5 m, stems ascending to ± erect, generally not rooting at nodes ..... C. divergens (2)

4' Plant generally erect, 1–4+ m; stems ascending to erect, occasionally intricately branched, not rooting at nodes

18. Leaf blade ± wavy to ± folded lengthwise, margin teeth spine-like

19. Leaf blade elliptic to narrowly obovate ..... C. divergens (2)

19' Leaf blade widely elliptic to ± round

20. Leaves ± spreading, margin 3–5-toothed ..... C. sonomensis

20' Leaves generally reflexed, margin 7–15-toothed

21. Sepals, petals 6–8; fruit 5–7 mm, wrinkled, horns thick; flowers white to blue; generally serpentine ..... C. jepsonii

21' Sepals, petals 5; fruit 4–5 mm, smooth, horns slender; flowers dark blue to purple; volcanic substrates ..... C. purpureus

18' Leaf blade generally flat or convex to concave adaxially, margin entire or teeth ± sharp, not spine-like

22. Leaf blade densely tomentose abaxially, veins obscure, margin generally rolled under ..... C. crassifolius var. crassifolius

22' Leaf blade generally glabrous to strigose or puberulent abaxially (sparsely tomentose in Ceanothus crassifolius var. planus, ± tomentose in Ceanothus otayensis), veins generally evident, margin not rolled under (except Ceanothus otayensis)

23. Leaf margin generally entire, or teeth < 5, unevenly distributed

24. Leaf blade 3–7 mm, 1–3 mm wide, narrow-oblanceolate to -obovate; inflorescence generally < 1 cm; flowers generally pale blue, occasionally ± pink ..... C. ophiochilus

24' Leaf blade 5–30 mm, 3–19 mm wide, elliptic, oblanceolate, obovate, or ± round; inflorescence generally 1–2 cm; flowers generally white (pale blue to lavender in some Ceanothus cuneatus)

25. Flower disk dark; fruit 5–12 mm wide

26. Leaf tip obtuse to rounded; fruit 5–9 mm wide; s Outer South Coast Ranges, Western Transverse Ranges (Santa Barbara, Ventura cos.) ..... C. crassifolius var. planus

26' Leaf tip truncate to ± notched; fruit 7–12 mm wide; Channel Islands ..... C. megacarpus var. insularis

25' Flower disk generally not dark, white to pale blue or lavender; fruit 3–6 mm wide

27. Twigs generally dense-puberulent to short-tomentose, pale gray to ± white; leaf blade short-curly-puberulent abaxially ..... C. vestitus (2)

27' Twigs generally glabrous to ± puberulent, generally brown to gray-brown, leaf blade glabrous to ± strigose abaxially ..... C. cuneatus

28. Flower generally white; twigs generally gray-brown; leaf blade tip acute to ± rounded ..... var. cuneatus

28' Flower generally blue to lavender; twigs generally brown; leaf blade tip truncate to notched

29. Leaves at nodes and in axillary clusters, node leaves widely obovate, clustered leaves oblanceolate to narrowly obovate ..... var. fascicularis

29' Leaves at nodes, blades widely obovate to ± round ..... var. ramulosus

23' Leaf margin generally dentate to ± serrate, teeth generally 5–35 (occasionally < 5 in Ceanothus vestitus), ± evenly distributed, or in distal 1/2, occasionally minute

30. Twigs generally angled, especially distally

31. Leaf blade 13–45 mm, widely obovate to ± round, margin 13–35-toothed ..... C. gloriosus var. exaltatus

31' Leaf blade 7–21 mm, obovate to narrowly obovate, margin 9–17-toothed ..... C. masonii

30' Twigs generally not angled

32. Leaf blade generally 10–25+ mm

33. Leaf blade dark green, obovate to widely elliptic; fruit 6–9 mm wide, ± wrinkled, horns 1–2 mm; se San Francisco Bay Area (Santa Clara Co.) ..... C. ferrisiae

33' Leaf blade green to yellow-green, widely elliptic to ± round; fruit 3–5 mm wide, generally smooth or ± 3-bulged distally, horns < 1 mm or 0; e Transverse Ranges, Peninsular Ranges ..... C. perplexans

32' Leaf blade generally <= 12 mm (except some Ceanothus vestitus 5–20 mm)

34. Leaf blade ± tomentose abaxially, glabrous in age, veins obscure, margin thick or rolled under — s Peninsular Ranges (Otay, San Miguel mtns) ..... C. otayensis

34' Leaf blade glabrous to short-strigose or short-curly-puberulent abaxially, occasionally glabrous in age, veins evident, margin generally not rolled under, occasionally thick

35. Flowers generally blue to lavender (white), leaf tip rounded to truncate, margin entire or 5–9-toothed ..... C. rigidus (2)

35' Flowers generally white; leaf tip generally acute to obtuse, margin entire or 3–5-toothed ..... C. vestitus (2)

1' Stipules scale-like, thin, deciduous; leaves alternate; inflorescence generally raceme- to panicle-, occasionally ± umbel-like (subg. Ceanothus)

36. Twigs rigid, generally thorn-like

37. Leaf blade 1-ribbed from base, shiny green adaxially; twigs green ..... C. spinosus (2)

37' Leaf blade 3-ribbed from base, dull green adaxially; twigs pale gray to gray-green

38. Plant generally < 1.5 m; stems generally spreading; inflorescence 1–4 cm, generally sessile ..... C. cordulatus

38' Plant generally 1.5–4 m; stems ascending to erect; inflorescence 3–15 cm, generally stalked

39. Leaf blade wide-elliptic to -ovate, 20–50+ mm, 10–45 mm wide; fruit coarse-wrinkled when dry ..... C. incanus (2)

39' Leaf blade elliptic to ovate, 12–30 mm, 3–15 mm wide; fruit smooth to ± wrinkled when dry ..... C. leucodermis

36' Twigs flexible, not thorn-like

40. Leaf blade generally 1-ribbed from base

41. Plant mat- to mound-like, generally < 0.5 m; stem spreading to ascending

42. Leaf margin rolled under; blade tomentose abaxially, tip truncate to notched ..... C. hearstiorum

42' Leaf margin not rolled under; blade glabrous, puberulent, or short-wavy-hairy abaxially, tip acute to ± rounded

43. Petiole 1–3 mm; leaf blade ± wavy, ± folded lengthwise, glabrous abaxially except veins; margin entire to few-toothed distally ..... C. foliosus var. vineatus

43' Petiole 3–11 mm; leaf blade generally not ± wavy, not ± folded lengthwise, puberulent to tomentose abaxially; margin 27–45-toothed

44. Plant generally mat-like, generally < 0.3 m, rooting at nodes; inflorescences on short, erect twigs; twigs green, occasionally tinged red ..... C. diversifolius (2)

44' Plant erect to mound-like, 0.5–1 m, not rooting at nodes; inflorescences not on short, erect twigs; twigs pale green to gray-green ..... C. lemmonii (3)

41' Plant generally erect, occasionally tree-like, > 0.5 m (occasionally mound-like in Ceanothus papillosus); stem ascending to erect

45. Leaf blade margin thick or rolled under

46. Leaf blade widely ovate to ± round, furrowed along veins adaxially, tip acute to obtuse ..... C. impressus

47. Leaf blade 5–14 mm; plant 0.5–1.5 m, generally dense ..... var. impressus

47' Leaf blade 11–25 mm; plant 1–3 m, generally open ..... var. nipomensis

46' Leaf blade ± oblong or narrowly elliptic, not furrowed adaxially, tip truncate to notched

48. Plant generally 0.5–1.5 m; leaf blade 4–16 mm, 2–8 mm wide, not glandular-papillate adaxially, glandular-papillate near margin ..... C. dentatus

48' Plant 1–3.5 m; leaf blade 11–50 mm, 6–15 mm wide, glandular-papillate adaxially and on margin ..... C. papillosus

45' Leaf blade margin generally not thick, generally not rolled under (partly rolled under in Ceanothus parryi)

49. Leaf margin generally gland-toothed, glands generally dark, ± persistent

50. Leaf margin ± rolled under, especially below middle, occasionally minutely glandular; blade cobwebby to loose-tomentose abaxially ..... C. parryi (2)

50' Leaf margin entire or minutely gland-toothed; blade glabrous to puberulent abaxially

51. Twigs pale green to gray-green; petiole 3–6 mm; leaf blade flat ..... C. lemmonii (3)

51' Twigs green to red-green; petiole 1–3 mm; leaf blade generally wavy, ± folded lengthwise ..... C. foliosus (2)

52. Leaf blade ± glabrous to sparsely puberulent abaxially; plants ± open ..... var. foliosus (2)

52' Leaf blade densely short-wavy-hairy abaxially; plants ± dense ..... var. medius (2)

49' Leaf margin generally entire (or minutely gland-toothed, glands not dark, not persistent)

53. Plant generally < 1.5 m, stems ± spreading to generally ascending; leaf blade tip obtuse; inflorescence 4–9 cm, raceme- to panicle-like; High Sierra Nevada ..... C. parvifolius (2)

53' Plant generally 1–6 m, occasionally tree-like, stems ascending to erect; leaf blade tip acute to obtuse; inflorescence 4–21 cm, generally panicle-like; not High Sierra Nevada

54. Flowers blue to pale blue; leaf blade generally dark shiny green adaxially — s Outer South Coast Ranges, Western Transverse Ranges, Peninsular Ranges ..... C. spinosus (2)

54' Flowers white; leaf blade generally dull to light green adaxially, occasionally shiny

55. Leaf blade elliptic to ± oblong, thin; fruit 4–6.5 mm wide; sw San Francisco Bay Area (Santa Cruz Mtns) ..... C. integerrimus var. integerrimus

55' Leaf blade elliptic to oblong-ovate, ± thick; fruit 6–9 mm wide; n&c Sierra Nevada Foothills, s South Coast Ranges, Transverse Ranges, Peninsular Ranges ..... C. palmeri

40' Leaf blade generally 3-ribbed from base

56. Leaf margin entire (minutely toothed)

57. Main stem generally ascending to ± spreading; leaf blade 3–12 mm wide, shiny green adaxially ..... C. parvifolius (2)

57' Main stem ascending to erect; leaf blade 10–45 mm wide, dull green adaxially

58. Twigs rigid, pale gray to gray-green; leaf blade abaxially gray-green, strigose; fruit wrinkled ..... C. incanus (2)

58' Twigs flexible, generally green; leaf blade abaxially pale green, glabrous to sparsely short-hairy, especially veins; fruit smooth to bulged or ± 3-ridged distally ..... C. integerrimus var. macrothyrsus

56' Leaf margin minutely toothed or serrate, teeth generally gland-tipped

59. Leaf blade generally tomentose abaxially, veins ± obscured by hairs

60. Leaf blade 25–80 mm, thick, leathery; petiole 10–25 mm; Channel Islands ..... C. arboreus (2)

60' Leaf blade 10–25 mm, generally thin, not leathery; petiole 1–3 mm; mainland ..... C. tomentosus

59' Leaf blade ± glabrous to puberulent or short-wavy-hairy abaxially, veins not obscured by hairs

61. Leaf blade generally 25–80 mm, 13–60 mm wide, generally widely elliptic to ovate

62. Flowers generally blue; fruit 5–8 mm wide, black; Channel Islands ..... C. arboreus (2)

62' Flowers white; fruit 3–4.5 mm wide, brown; mainland

63. Leaf deciduous, not aromatic; blade thin, not leathery, not sticky adaxially ..... C. sanguineus

63' Leaf evergreen, aromatic; blade leathery, ± sticky adaxially ..... C. velutinus

61' Leaf blade generally 5–45 mm, 3–25 mm wide, elliptic, oblong-elliptic, oblanceolate (ovate)

64. Plant mat- to mound-like, generally < 1 m; stems ± ascending to spreading

65. Twigs angled distally; leaf blade abaxial veins ± raised ..... C. thyrsiflorus (2)

66. Twigs ± puberulent; leaf blade ovate to widely elliptic, margin rolled under ..... var. griseus (2)

66' Twigs ± glabrous; leaf blade oblong-ovate to elliptic, margin not to partly rolled under ..... var. thyrsiflorus (2)

65' Twigs not angled distally; leaf blade abaxial veins ± not raised

67. Plant generally mat-like, generally < 0.3 m; stem rooting at nodes; twigs green, occasionally tinged red; fruit 4–5 mm wide ..... C. diversifolius (2)

67' Plant ± mound-like, generally > 0.5 m, stem not rooting at nodes; twigs pale green to gray-green; fruit 3–4 mm wide ..... C. lemmonii (3)

64' Plant not mat- to mound-like, generally 1–4 m; stems ascending to erect

68. Twigs generally angled distally, internodes ridged

69. Leaf blade ± oblong to narrowly elliptic, length generally > 2 × width, cobwebby to loose-tomentose abaxially, glabrous in age ..... C. parryi (2)

69' Leaf blade generally ovate to elliptic, length generally < 2 × width, glabrous to ± puberulent abaxially, especially on veins

70. Inflorescence 5–30 cm; twigs papillate; leaf blade abaxial veins ± not raised ..... C. cyaneus

70' Inflorescence 1.5–7 cm; twigs not papillate; leaf blade abaxial veins ± raised ..... C. thyrsiflorus (2)

71. Twigs ± puberulent; leaf blade ovate to widely elliptic, margin rolled under ..... var. griseus (2)

71' Twigs ± glabrous; leaf blade oblong-ovate to elliptic, margin not to partly rolled under ..... var. thyrsiflorus (2)

68' Twigs not angled distally, internodes not ridged

72. Leaf blade flat or generally wavy, ± folded lengthwise; petiole 1–3 mm; fruit 3–4 mm wide ..... C. foliosus (2)

73. Leaf blade glabrous to sparsely puberulent abaxially; plant ± open ..... var. foliosus (2)

73' Leaf blade densely short-wavy-hairy abaxially; plant ± dense ..... var. medius (2)

72' Leaf blade generally flat; petiole 3–7 mm; fruit 4–7 mm wide ..... C. oliganthus

74. Flower disk, ovary short-hairy; fruit prominently wrinkled ..... var. orcuttii

74' Flower disk, ovary glabrous; fruit generally smooth or ± ridged to bulged near top

75. Twigs puberulent; leaf blade short-hairy adaxially ..... var. oliganthus

75' Twigs ± glabrous; leaf blade glabrous to sparsely short-hairy adaxially ..... var. sorediatus

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