Asteraceae tribe Senecioneae

Annuals, perennials, subshrubs, shrubs, trees, or vines. Leaves usually cauline, sometimes mostly basal or basal and cauline; usually alternate [opposite]; usually petiolate (rarely peltate), sometimes sessile; margins entire or dentate to pinnatifid (leaves sometimes becoming spines, e.g., Tetradymia spp.). Heads homogamous (discoid) or heterogamous (disciform or radiate), usually in corymbiform, paniculiform, racemiform, or spiciform arrays, sometimes borne singly. Calyculi 0 or of 1–15+ bractlets in 1(–2+) series. Phyllaries persistent or falling, usually in 1–2 series, usually distinct, equal to subequal, and herbaceous, rarely in 3–5+ series, distinct, unequal, and herbaceous to chartaceous (e.g., Lepidospartum), margins and/or apices notably to barely scarious. Receptacles usually flat to convex, sometimes conic, epaleate (sometimes pitted, pit margins often fimbrillate). Ray florets 0 or in 1(–2+) series, usually pistillate and fertile, rarely neuter or styliferous and sterile; corollas usually yellow to orange, sometimes ochroleucous or reddish to cyanic. Peripheral (pistillate) florets 0 or (in disciform heads) in 1–3+ series; corollas (usually present) usually yellow, sometimes ochroleucous or reddish to cyanic. Disc (inner) florets usually bisexual and fertile, rarely functionally staminate; corollas usually yellow to orange, sometimes ochroleucous or reddish to cyanic, not 2-lipped, lobes (4–)5, usually deltate, sometimes lanceolate to lance-linear; anther bases obtuse or rounded, not tailed (sometimes sagittate), apical appendages usually ovate to lance-linear; styles abaxially glabrous or papillate (distally), branches ± linear, adaxially stigmatic, usually in 2 lines, sometimes continuously, from bases to apices or appendages, apices rounded to ± truncate or with deltate to lanceolate or penicillate, abaxially and adaxially papillate to hispidulous appendages (appendages sometimes essentially 0). Cypselae usually monomorphic within heads, usually ± columnar to prismatic, seldom compressed, obcompressed, or flattened, rarely, if ever, beaked, bodies usually ribbed or nerved, rarely winged (glabrous or hairy); pappi (rarely 0) usually persistent (then often fragile, sometimes readily falling), usually of smooth or barbellulate bristles (in 1–5+ series), rarely of scales (scales often aristate, setiform, or subulate).

Distribution

Almost worldwide, mostly temperate to subtropical.

Discussion

Genera ca. 120, species 3200+ (29 genera, 167 species in the flora).

Most (not all) members of Senecioneae are characterized by a combination of calyculate involucres of subequal to equal phyllaries in 1–2 series, receptacles epaleate, anthers not tailed, style branches truncate or truncate-penicillate, and pappi of fine bristles; exceptions for all those traits are known. Centers of diversity and/or species numbers are in Mexico, Central America, Andean South America, southern and tropical Africa, and central and eastern Asia.

Some members of Senecioneae are well-known horticultural plants (e.g., species of Doronicum, Emilia, Gynura, Ligularia, Pericallis, and Senecio). Other Senecionids are known for poisoning of livestock, mainly by alkaloids in Senecio spp. (mostly cattle and horses) and by furanoeremophilanes in Tetradymia spp. (mostly sheep).

The circumscription of Senecioneae adopted here is essentially that of K. Bremer (1994). Traditional circumscription of the tribe has experienced expansions and contractions over the decades as genera and groups of genera have been moved in and out. Most genera that have been removed from Senecioneae in its broadest sense have come to rest within Liabeae (none in our flora) or within a broadly circumscribed Heliantheae (e.g., Arnica and allies in Arnicinae, Chaenactidinae, or Madiinae; Haploësthes in Flaveriinae; Raillardella and allies in Madiinae). Additional information may be found in B. G. Baldwin et al. (2002), H. Robinson (1981), and B. Nordenstam (1977[1978]).

Senecionid shrubs with ovate to elliptic, pinnately divided leaf blades mostly 3–8+ cm and radiate heads with yellow corollas (laminae mostly 15–25+ mm) borne on peduncles mostly 3–15+ cm are cultivated in warm areas of the flora and may be encountered sporadically outside plantings. They have been called Euryops pectinatus (Linnaeus) Cassini and/or E. chrysanthemoides (de Candolle) B. Nordenstam.

Selected References

Barkley, T. M. 1978. Senecio. In: N. L. Britton et al., eds. 1905+. North American Flora.... 47+ vols. New York. Ser. 2, part 10, pp. 50–139.

Barkley, T. M., B. L. Clark, and A. M. Funston. 1996. The segregate genera of Senecio sensu lato and Cacalia sensu lato in Mexico and Central America. In: D. J. N. Hind et al., eds. 1996. Proceedings of the International Compositae Conference, Kew, 1994. 2 vols. Kew. Vol. 1, pp. 613–620.

Barkley, T. M. 1999. The segregates of Senecio, s.l., and Cacalia, s.l., in the flora of North America North of Mexico. Sida 18: 661–672.

Jeffrey, C. 1980. Generic and sectional limits in Senecio (Compositae): II. Evaluation of some recent studies. Kew Bull. 34: 49–58.

Nordenstam, B. 1977[1978]. Senecioneae and Liabeae—systematic review. In: V. H. Heywood et al., eds. 1977[1978]. The Biology and Chemistry of the Compositae. London, New York, and San Francisco. Vol. 2, pp. 800–830.

Pippen, R. W. 1968. Mexican “cacalioid” genera allied to Senecio (Composite). Contr. U.S. Natl. Herb. 34: 365–447.

Swenson, U. 1995. Systematics of the Blennospermatinae (Asteraceae, Senecioneae). Ph.D. dissertation. Uppsala University.

Lower Taxa

Arnoglossum, Barkleyanthus, Blennosperma, Cacaliopsis, Crocidium, Delairea, Doronicum, Emilia, Erechtites, Gynura, Hasteola, Lepidospartum, Ligularia, Luina, Packera, Parasenecio, Pericallis, Petasites, Psacalium, Pseudogynoxys, Rainiera, Roldana, Rugelia, Senecio, Sinosenecio, Tephroseris, Tetradymia, Tussilago, Yermo

Key

1	Heads radiate	> 2
1	Heads discoid or disciform	> 19
2	Shrubs or vines	> 3
2	Annuals, biennials, perennials, or subshrubs	> 5
3	Vines (usually ± twining and climbing; corollas orange to ± brick-red); Florida	Pseudogynoxys
3	Shrubs	> 4
4	Leaves lance-elliptic or lanceolate to lance-linear (clustered distally on branches); Arizona, New Mexico	Barkleyanthus
4	Leaves (or lobes) linear (± evenly distributed)	Senecio
5	Annuals	> 6
5	Biennials, perennials, or subshrubs	> 10
6	Disc florets functionally staminate (not producing cypselae)	Blennosperma
6	Disc florets bisexual, fertile	> 7
7	Receptacles dome-shaped to conic (heights equaling or greater than diameters)	Crocidium
7	Receptacles flat to convex (sometimes ± dome-shaped in Tephroseris)	> 8
8	Style branches: stigmatic areas continuous (stamen filaments cylindric, not distally expanded)	Tephroseris
8	Style branches: stigmatic in 2 lines (stamen filaments distally expanded into swollen collars)	> 9
9	Leaves basal and/or cauline (roots often fleshy and seldom branched and/or leaf margins with relatively many callous denticles; 2n = 20 or 40 or polyploid derivatives)	Senecio
9	Leaves basal and cauline (roots seldom fleshy, often branched; leaf margins with relatively few or no callous denticles; 2n = 40, 44, or 46 or polyploid derivatives)	Packera
10	Disc florets (all or mostly) functionally staminate (not producing cypselae)	> 11
10	Disc florets (all or mostly) bisexual, fertile	> 12
11	Heads usually borne singly; ray florets 100–200(–300+), corollas yellow (drying pinkish)	Tussilago
11	Heads usually in corymbiform, paniculiform, or racemiform arrays, rarely borne singly; ray florets (1–)30–130+, corollas whitish or pinkish to purplish	Petasites
12	Style branches: stigmatic in 2 lines (stamen filaments usually distally expanded into swollen collars)	> 13
12	Style branches: stigmatic areas continuous (stamen filaments cylindric, not distally expanded)	> 15
13	Ray corollas usually whitish or bluish, pinkish, purplish, or reddish (often proximally pale and distally darker); pappi readily falling, usually of 20–40+ bristles (discs), sometimes of 2 subulate to setiform scales or 0 (rays)	Pericallis
13	Ray corollas usually yellow to orange, sometimes ochroleucous, orange-red, or white, rarely purplish to reddish; pappi persistent or readily falling, usually of 30–80+ bristles	> 14
14	Leaves basal and/or cauline (roots often fleshy and seldom branched and/or leaf margins with relatively many callous denticles; 2n = 20 or 40 or polyploid derivatives)	Senecio
14	Leaves basal and cauline (roots seldom fleshy, often branched; leaf margins with relatively few or no callous denticles; 2n = 40, 44, or 46 or polyploid derivatives)	Packera
15	Petiole bases usually dilated (sheathing stems); laminae of ray corollas orange to orange-yellow or brick-red (20–50 mm); pappi reddish; Maryland	Ligularia
15	Petiole bases rarely dilated (except Doronicum and Sinosenecio); laminae of ray corollas usually yellow, sometimes yellow-orange or orange, rarely ochroleucous or white (mostly 2–15 mm, if 20+ mm, yellow); pappi white or stramineous to brownish	> 16
16	Phyllaries in 2–3+ series, margins seldom scarious (often ciliate); ray florets 21–40+ (ray cypselae often epappose)	Doronicum
16	Phyllaries in (1–)2 series, margins ± scarious (seldom ciliate); ray florets mostly 5, 8, 13, or 21	> 17
17	Leaf blades (at least proximal) suborbiculate (lengths mostly 1–1.5 times widths and plants 60–300 cm; corolla tubes usually glandular-puberulent); s Arizona	Roldana
17	Leaf blades seldom suborbiculate (lengths mostly 3–10+ times widths; if suborbiculate, plants 3–60+ cm; corolla tubes seldom, if ever, glandular-puberulent)	> 18
18	Leaf blades pinnately nerved, lanceolate, linear-oblanceolate, oblanceolate, ovate, or subrhombic	Tephroseris
18	Leaf blades palmately or subpalmately nerved, ovate to subreniform; British Columbia	Sinosenecio
19	Heads disciform	> 20
19	Heads discoid	> 22
20	Leaf blades palmately or palmati-pinnately nerved, mostly deltate to ovate or orbiculate (plants polygamodioecious, stems of "staminate" plants wither soon after flowering, stems of "pistillate" plants elongate after flowering)	Petasites
20	Leaf blades pinnately nerved, mostly ovate or obovate to lanceolate (sometimes pinnately lobed or dissected)	> 21
21	Pistillate florets sometimes 1–3 in 1 series (usually 0, heads usually discoid, Senecio mohavensis)	Senecio
21	Pistillate florets 10–100+ in 1–3 series	Erechtites
22	Subshrubs, shrubs (treelets), or vines	> 23
22	Annuals, biennials, or perennials	> 26
23	Vines; California, Oregon	Delairea
23	Subshrubs or shrubs (treelets)	> 24
24	Phyllaries 4–6 in 1–2 series and equal or subequal; florets 4–9	Tetradymia
24	Phyllaries mostly 5, 8, 13, or 21 in (1–)2 series and equal or subequal, or 8–13 or 12–23+ in 2–4+ series and unequal (outer shorter); florets 3–80+	> 25
25	Phyllaries mostly 5, 8, 13, or 21 in (1–)2 series and equal or subequal	Senecio
25	Phyllaries 8–13 or 12–23+ in 2–4+ series and unequal (leaves of flowering stems filiform to acerose or scalelike)	Lepidospartum
26	Plants ± velutinous or villous (hairs purplish); style-branch appendages ± filiform (hispidulous, 1–2 mm; perennials); s Florida	Gynura
26	Plants rarely velutinous or villous (hairs rarely purplish); style-branch appendages essentially 0 (or deltoid to conic, mostly 0.1–1 mm; style-branch apices usually truncate-penicillate or truncate to rounded-truncate)	> 27
27	Phyllaries (4–)5(–6; yellow); Wyoming	Yermo
27	Phyllaries (4–)5–30+ (usually green)	> 28
28	Corollas usually yellow, sometimes orange-yellow or orange, rarely orange-red, purplish, or reddish	> 29
28	Corollas usually white or ochroleucous to greenish or whitish, sometimes lavender, pinkish, or purplish	> 34
29	Heads in racemiform or subthyrsiform arrays; phyllaries (4–)5(–8); florets (4–)5(–8)	Rainiera
29	Heads usually in corymbiform, sometimes cymiform, racemiform, or subumbelliform, arrays or borne singly; phyllaries (5–)8–30+; florets (5–)20–80+	> 30
30	Calyculi usually of 1–8+ bractlets, sometimes 0; style-branch apices usually truncate-penicillate	> 31
30	Calyculi 0; style-branch apices usually rounded-truncate or with deltoid to conic appendages	> 32
31	Leaves basal and/or cauline (roots often fleshy and seldom branched and/or leaf margins with relatively many callous denticles; 2n = 20 or 40 or polyploid derivatives)	Senecio
31	Leaves basal and cauline (roots seldom fleshy, often branched; leaf margins with relatively few or no callous denticles; 2n = 40, 44, or 46 or polyploid derivatives)	Packera
32	Involucres 3–8 mm diam.; florets 11–26	Luina
32	Involucres 7–15+ mm diam.; florets 20–80+	> 33
33	Leaf blades pinnately nerved, lanceolate, linear-oblanceolate, oblanceolate, ovate, or subrhombic	Tephroseris
33	Leaf blades palmately nerved, ± reniform to orbiculate	Cacaliopsis
34	Leaf blades palmately or palmati-pinnately nerved, mostly deltate to ovate or orbiculate (plants polygamodioecious, stems of "staminate" plants wither soon after flowering, stems of "pistillate" plants elongate after flowering)	Petasites
34	Leaf blades palmately, palmati-pinnately, or pinnately nerved, mostly ovate, obovate, oblanceolate, or elliptic to lanceolate, lance-linear, or linear, sometimes cordate, deltate, hastate, reniform, or orbiculate (plants not poly-gamodioecious)	> 35
35	Annuals	Emilia
35	Perennials	> 36
36	Phyllaries 5–8; florets 4–8	> 37
36	Phyllaries 7–21; florets 10–80+	> 39
37	Heads in racemiform to subpaniculiform arrays; Alaska	Parasenecio
37	Heads usually in corymbiform, sometimes paniculiform, arrays	> 38
38	Basal and proximal cauline leaf blades ovate to elliptic (deeply 3–4-pinnatisect); calyculi of 1–3 bractlets; s Arizona, New Mexico	Psacalium
38	Basal and proximal cauline leaf blades mostly cordate, deltate, elliptic, hastate, ovate, or reniform, sometimes lanceolate or lance-linear (not 3–4-pinnatisect); calyculi 0; e North America	Arnoglossum
39	Plants (50–)60–240 cm; calyculi of 4–9+ (subulate, rarely leaflike) bractlets	Hasteola
39	Plants 10–50 cm; calyculi 0 or of 1–3 bractlets	> 40
40	Leaf blades ovate to subrhombic (1–3 × 1–2 cm)	Tephroseris
40	Leaf blades ovate to nearly cordate (5–15+ × 3–10+ cm)	Rugelia