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Key to families | Table of families and genera
This text currently parallels The Jepson Manual: Vascular Plants of California, Second Edition that is now available at the University of California Press.
Text appearing in blue on this page will not appear in the printed book; it will be displayed only on the Web. 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.
Annual to shrub, from taproot, rhizome, or button-like caudex.
Stem: 1–many, simple or branched.
Leaf: alternate; mostly basal to evenly distributed; proximal generally ± petioled; middle generally reduced, sessile, often clasping.
Inflorescence: heads radiate, disciform, or discoid, generally in cyme-like clusters; involucre cylindric to urn- or bell-shaped, main phyllaries generally 8, 13, or 21 in 1 series, subtended by few to many, generally much- reduced outer phyllaries, reflexed in fruit, green, often black-tipped, linear to narrowly lanceolate, glabrous or hairy; receptacle epaleate.
Ray flower: 0–21; ray generally yellow (white, pink-purple), occasionally much- reduced and scarcely exceeding phyllaries.
Disk flower: 3–100+; corolla tubular to bell-shaped, lobes erect to recurved, pale to deep yellow; anther tip ± triangular- ovate; style branch tips obtuse or truncate.
Fruit: cylindric, generally shallow-ribbed or -angled, glabrous or stiff-hairy; pappus of minutely barbed bristles, white to tan.
1000+ species: worldwide, especially abundant in warm temperate, subtrop and tropical areas at mid to upper elevations. (Latin: old man, from white pappus) [Barkley 2006 FNANM 20:544–570] Many North America species formerly treated as Senecio now in Packera. The common names groundsel, ragwort, and butterweed apply to species of both genera. Neither Pericallis hybrida B. Nord. [Senecio hybridus Regel, illeg.] nor Senecio squalidus L. <WEEDINESS SYMBOL 1> naturalized in CA; Senecio hieraciifolius L. var. hieraciifolius [Erechtites hieraciifolia (L.) DC. var. hieraciifolia (orth. var.)] not documented in CA.
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; CW, SCo, ChI ..... 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; D ..... S. mohavensis (2)
3' Pistillate flowers more numerous than disk flowers
6. Lvs pinnately lobed ..... S. glomeratus
6' Lvs 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
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. Fls 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' Fls 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. Lvs 1–2-pinnately divided into linear, entire lobes ..... S. lyonii
18' Lvs generally entire or toothed (occasionally lobed in Senecio spartioides)
19. Phyllaries 3–5 mm ..... S. linearifolius var. linearifolius
19' Phyllaries 6–10 mm
20. Lf 0.5–3 mm wide; phyllaries generally 13; involucre generally 7–9 mm wide when pressed; fruit 3–5 mm; s CCo ..... S. blochmaniae
20' Lf 1–6 mm wide; phyllaries 8(13); involucre generally 3–6 mm wide when pressed; fruit 2–3.5 mm; SNH, SnBr, SNE, DMtns ..... S. spartioides
15' Annual or biennial to perennial herb; leaves or leaf segments of various shapes but generally wider than linear
22. Rays yellow ..... S. californicus
22' Rays red- or pink-purple ..... S. elegans
21' Biennial or per
23. Lvs deeply lobed or divided
24. Lvs sharply cut to pinnately lobed, lobes entire; phyllary tips green ..... S. clarkianus
24' Lvs 1–3-pinnately lobed, lobes obovate to spoon-shaped, ultimate margin dentate; phyllary tips generally black ..... S. jacobaea
23' Lvs entire or toothed
25. Rosette of basal leaves 0, leaves well distributed along stem
26. Plant generally 40–200 cm
27. Lvs ± linear to lanceolate, dentate to ± entire, tapered to ± sessile at base ..... S. serra var. serra
27' Lvs 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. Lf sharply toothed, minutely dentate, or ± entire; phyllaries 8 (rarely 13); ray flowers 0 or 1–2 ..... S. aronicoides (2)
33' Lf 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, http://ucjeps.berkeley.edu/IJM.html [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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