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    Vascular Plants of California
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Key to Senecio

View taxon page for Senecio

(For a list of species in Senecio, use the above link.)

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

1. Heads discoid, disciform, or minutely radiate, rays (if present) generally <= 2 mm, scarcely, if at all exceeding involucre

2. Heads disciform or minutely radiate, pistillate flowers present

3. Pistillate flowers fewer than disk flowers

4. Herbage densely curly-hairy; leaves 1–2-pinnately lobed or divided; disk flowers 40–50 ..... S. sylvaticus

4' Herbage glabrous or sparsely hairy; leaves generally dentate or 1-pinnately lobed; disk flowers 8–30

5. Cauline leaves generally narrowed at base, sometimes weakly clasping; involucre narrowly urn-shaped, finely hairy; Central Western California, South Coast, Channel Islands ..... S. aphanactis

5' Mid and distal cauline leaves widest at base, truncate to cordate-clasping – 1–2+ cm wide – at base, often ± purple tinged; involucre cylindric or urn-shaped, glabrous; Desert ..... S. mohavensis (2)

3' Pistillate flowers more numerous than disk flowers

6. Leaves pinnately lobed ..... S. glomeratus

6' Leaves dentate or minutely dentate

7. Cauline leaves ± narrowly lanceolate, ± clasping, sharply and evenly fine-dentate, flat ..... S. minimus

7' Cauline leaves linear or lance-linear, tapered to base, remotely minutely dentate or appearing entire, margins ± rolled under ..... S. quadridentatus

2' Heads discoid, pistillate flowers 0

8. Annual

9. Herbage glabrous, glaucous ..... S. mohavensis (2)

9' Herbage glabrous or sparsely hairy when young, not glaucous ..... S. vulgaris

8' Biennial or perennial herb

10. Plant glabrous or minutely hairy among heads

11. Caudex erect; herbage ± red-tinged, not glaucous; petioles winged, leaves firm, not fleshy, dentate or minutely dentate; wet hillsides and meadows ..... S. hydrophiloides (2)

11' Caudex short, button-like; herbage blue-green, glaucous; petioles unwinged, leaves ± fleshy, entire to dentate; swamps and alkaline soils ..... S. hydrophilus (2)

10' Plant ± hairy, occasionally becoming ± glabrous in age

12. Flowers 6–40 per head

13. Phyllaries (4)5–12 mm; disk flowers 35–45 ..... S. integerrimus var. exaltatus (2)

13' Phyllaries 3–5 mm; disk flowers 10–20 ..... S. scorzonella (2)

12' Flowers 40–90+ per head

14. Phyllaries 8(13), 4–8 mm ..... S. aronicoides (2)

14' Phyllaries ± 21, 7–10 mm ..... S. astephanus

1' Heads radiate, rays 3–20 mm, generally well exceeding involucre

15. Shrub or subshrub with shrub-like branching; leaves or leaf segments narrowly linear to thread-like

16. Outer phyllaries prominent, often some > 1/2 inner ..... S. flaccidus

17. Herbage generally ± gray-tomentose ..... var. douglasii

17' Herbage generally ± glabrous ..... var. monoensis

16' Outer phyllaries inconspicuous or 0

18. Leaves 1–2-pinnately divided into linear, entire lobes ..... S. lyonii

18' Leaves generally entire or toothed (occasionally lobed in Senecio spartioides)

19. Phyllaries 3–5 mm ..... S. linearifolius var. linearifolius

19' Phyllaries 6–10 mm

20. Leaf 0.5–3 mm wide; phyllaries generally 13; involucre generally 7–9 mm wide when pressed; fruit 3–5 mm; s Central Coast ..... S. blochmaniae

20' Leaf 1–6 mm wide; phyllaries 8(13); involucre generally 3–6 mm wide when pressed; fruit 2–3.5 mm; High Sierra Nevada, San Bernardino Mountains, East of Sierra Nevada, Desert Mountains ..... S. spartioides

15' Annual or biennial to perennial herb; leaves or leaf segments of various shapes but generally wider than linear

21. Annual

22. Rays yellow ..... S. californicus

22' Rays red- or pink-purple ..... S. elegans

21' Biennial or perennial herb

23. Leaves deeply lobed or divided

24. Leaves sharply cut to pinnately lobed, lobes entire; phyllary tips green ..... S. clarkianus

24' Leaves 1–3-pinnately lobed, lobes obovate to spoon-shaped, ultimate margin dentate; phyllary tips generally black ..... S. jacobaea

23' Leaves entire or toothed

25. Rosette of basal leaves 0, leaves well distributed along stem

26. Plant generally 40–200 cm

27. Leaves ± linear to lanceolate, dentate to ± entire, tapered to ± sessile at base ..... S. serra var. serra

27' Leaves narrowly to widely triangular, dentate (rarely ± entire), at least proximal truncate to cordate at base ..... S. triangularis

26' Plant 2–30 cm

28. Plants <= 10 cm from branching rhizomes; stems 1–3; leaf entire, wavy or curled under; ray 5–10 mm ..... S. pattersonensis

28' Plants 10–30 cm from ± rhizomatous spreading bases; stems 2–several; leaf toothed to ± entire; ray 8–12 mm ..... S. fremontii

29. Distal leaves well developed; phyllaries 7–10 mm ..... var. fremontii

29' Distal leaves smaller, fewer; phyllaries 5–7 mm ..... var. occidentalis

25' Rosette of basal leaves present, leaves generally reduced distally on stem

30. Plant with stout rhizome ..... S. scorzonella (2)

30' Plant with short, erect, ± button-like caudex bearing many fleshy-fibrous roots

31. Plant generally glabrous or nearly so

32. Caudex erect; herbage ± red-tinged, not glaucous; petioles winged, leaves firm, not fleshy, dentate or minutely dentate; wet hillsides and meadows ..... S. hydrophiloides (2)

32' Caudex short, button-like; herbage blue-green, glaucous; petioles unwinged, leaves ± fleshy, entire to dentate; swamps, alkaline soils ..... S. hydrophilus (2)

31' Plant hairy when young, often ± glabrous in age

33. Leaf sharply toothed, minutely dentate, or ± entire; phyllaries 8 (rarely 13); ray flowers 0 or 1–2 ..... S. aronicoides (2)

33' Leaf entire to ± dentate; phyllaries 13 or 21; ray flowers 5, 8 or 13 ..... S. integerrimus

34. Ray flowers white; basal leaves distinctly petioled, blades ovate to rounded-deltate, or rarely obovate to oblanceolate ..... var. ochroleucus

34' Ray flowers yellow; basal leaves distinctly petioled or not, blades elliptic to lanceolate or oblanceolate, occasionally rounded-deltate to ± round

35. Plant densely or sparsely hairy; phyllaries lanceolate, tips black ..... var. exaltatus (2)

35' Plant distinctly and densely hairy; phyllaries linear to awl-like, tips generally green, rarely minutely black-tipped ..... var. major


Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, [accessed on month, day, year]

Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].

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