Senecio L.

Herbs, undershrubs or shrubs. Annual or perennial, erect, decumbent or scandent, rhizomatous; stems usually leafy, rarely subscapiform. Leaves both radical and cauline; radical leaves exauriculate, lyrate or pinnately divided, usually petiolate; cauline leaves simple, lyrate or pinnately lobed, auriculate at the base, margins dentate, serrate or toothed, usually sessile. Capitula heterogamous, radiate, or homogamous, discoid or disciform, solitary, axillary or few to many in terminal, simple or compound corymb or thyrse, pedunculate. Involucre hemispherical, campanulate or cylindrical, calyculate; bracts 5-22, uniseriate, equal, free or connate at the base, herbaceous with scarious margins. Receptacle flat, naked, pitted or fimbriate. Ray florets yellow to orange, 1 - 24, ligulate, usually conspicuous, 3 - 9 veined, apically 3-dentate. Disc florets yellow, 3-numerous, tubular, 5-lobed. Anthers oblong to linear, base obtuse, not tailed. Style arms curved, truncate with obtuse marginal papillae. Achenes cylindrical 5 - 10 ribbed, smooth, glabrous to pubescent. Pappus white, stramineous or rufous, of capillary, uniform or barbellate hairs, sometimes absent in the. ray florets. Pollen spherical, more or less spiny, prominently tricol porate.

Cosmopolitan, ca 1000 species; 43 in India.

Literature. CHATER, A.O. (1974). Taxonomic and Nomenclature notes on Senecio L. Bot. J. linn. Soc. 68: 272 - 276. CUFODONTIS, G. (1933). Kritisch Revision von Senecio. Sectio. Tephroseris. Fedde, Rep. Beih. 70: 1 - 266. DRURY, D.G. & L. WATSON. (1966). A bizarre pappus form in Senecio. Taxon 15: 309 - 311. JEFFREY, C. (1979a). Generic and sectional limits in Senecio (Compositae): 11. Evaluation of some recent studies. Kew Bull. 34: 49 - 58. JEFFREY. C., f. HALLIDAY, M. WILMOT-DEAR. & S.W. JONES, (1977). Generic and Sectional limits in Senecio (Compositae) : 1. Progress Report. Kew Bull. 32: 47 - 67. PARKER, J.G. (1972). A Taxonomic and phytogeographical review of some Arctic and Alpine Senecio species Canad. J. Bot. 50(3): 517 - 518.

Notes. One of the largest, cosmopolitan genera with ca 3000 species. A polymorphic genus. It is considered to be the most primitive in the entire family. Recently the complex genus is segregated into several other distinct genera.

The genus is of considerable toxicological importance in some countries, viz. S. Africa, New Zealand and Nova Scotia. Several poisonous alkaloids have been isolated from species belonging to this genus. Cases of chronic poisoning by Senecio in man have been recorded particularly from Rivers dale, Cape Province. The symptoms are dyspepsia, abdominal pain and vomitting. The poisoning results from the accidental inclusion of the plant with wheat during harvesting and ineffective sieving of the grains (Chopra et al., Poisonous Pis. Ind. 590. 1949).

KEY TO THE SPECIES

1a. Capitula discoid

2

b. Capitula radiate

5

2a. Annual herbs; leaves pinnatifid, glabrous or pubescent

3

b. Perennial herbs; leaves dentate, white tomentose beneath

4

3a. Capitula campanulate; involucral bracts 12-16, green with purplish tip.

9. Senecio dubitabilis

b. Capitula conical; involucral bracts 18-22, with black tips

40. Senecio vulgaris

4a. Stems and branches reddish brown, black glandular pubescent; achenes pubescent

6. Senecio candolleanus

b. Stems and branches arachnoid with sparsely crispate pubescence; achenes glabrous

18. Senecio kumaonensis

5a. Erect herbs or shrubs

6

b. Climbing or scandent herbs or undershrubs

41

6a. Leaves both radical and cauline

7

b. Leaves only cauline

22

7a. Radical leaves long petioled, lyrate-pinnatifid; cauline leaves sessile, semi amplexicaul, lyrate-pinnatisect

8

b. Radical and cauline leaves not lyrate-pinnatifid, sessile or very shortly petioled

12

8a. Tall herbs or undershrubs; leaves glabrous or sparsely arachnoid tomentose beneath

9

b. Dwarf, perennial herbs; leaves white cottony tomentose beneath

11

9a. Involucre cylindrical

3. Senecio biligulatus

b. Involucre broadly campanulate

10

10a. Involucre 5-7 x 10-15 mm; ray florets ca 8 mm long; pappus always reddish brown

33. Senecio raphanifolius

b. Involucre 3-4 mm in diam.; ray florets ca 6.5 mm long; pappus pale-yellow

21. Senecio laetus

11a. Capitula with many, long bracteoles, adpressed to the purplish involucre

1. Senecio albopurpureus

b. Capitula with bracteoles scattered on the peduncle; involucre white cottony;

38. Senecio tibeticus

12a. Radical leaves rosulate at the base

13

b. Radical leaves not rosulate at the base

14

13a. Radical leaves obovate, obovate-oblong or spathulate, purplish beneath; involucral bracts distinctly 3-nerved

30. Senecio nudicaulis

b. Radical leaves elliptic, elliptic-lanceolate, greyish green beneath; involucral bracts obscurely nerved

31. Senecio obtusatus

14a. Pappus white

15

b. Pappus red, pale brown or stramincous

19

15a. Leaves linear-oblong, tomentose beneath

29. Senecio neelgherryanus

b. Leaves linear or broadly oblong to elliptic-oblong, glabrous to glandular pubescent

16

16a. Leaves broadly oblong, sessile, glandular pubescent on both the surfaces

27. Senecio mishmi

b. Leaves narrow, linear-oblong, glabrous or sparsely pubescent

17

17a. Leaves linear-oblong, obtuse, distantly serrate, auricled; auricles rounded

19. Senecio kundaicus

b. Leaves linear, long, acute or subacute, sessile, not auricled

18

18a. Leaves with apex dilated; ligules 16-20; achenes black, distinctly ribbed, glabrous

43. Senecio zeylanicus

b. Leaves with apex not dilated upwards; ligules 8-14; achenes not distinctly ribbed, scabrid

13. Senecio griffithii

19a. Glabrous herbs; leaves elongate, linear, sessile, not auricled, green

24. Senecio linifolius

b. Hispid or pubescent herbs; leaves auricled, reddish-brown

20

20a. Capitula large, broadly campanulate, on long, stout peduncle; pappus red

21

b. Capitula small, narrowly campanulate, on long, slender peduncle; pappus stramineous

42. Senecio wightii

21a. Leaves obovate, serrate, upper cauline leaves with dilated, auricled base

28. Senecio multiceps

b. Leaves linear-oblong, deeply toothed, without dilated, auricled base

23. Senecio lessingianus

22a. Leaves oblong, lanceolate, serrate or pinnatitid, never white tomentose beneath;

23

b. Leaves linear, oblong, obovate, elliptic-lanceolate, or rhomboidal, pinnatipartite, pubescent, white to grey tomentose beneath

31

23a. Rays of female, ligulate florets short, not exceeding the involucre

24

b. Rays of female ligulate florets over topping the involucre

26

24a. Erect, tall herbs, upto 60 cm high

32. Senecio ramosus

b. Dwarf herbs, upto 25 cm high

25

25a. Capitula narrowly cylindrical; peduncle upto 1 cm long,

20. Senecio ladakhensis

b. Capitula campanulate; peduncle 1.5 - 4 cm long

17. Senecio krascheninnikovii

26a. Lower cauline leaves shortly petioled; upper sessile and amplexicaul; ray florets revolute

8. Senecio desfontainei

b. All cauline leaves sessile; ray florets not revolute

27

27a. Glabrous herb.

28

b. Hispid, hirsute, densely puberulous or scabrous herbs

29

28a. Leaf lobes very slender, linear, spreading, acute; capitula on long, slender peduncle; pappus yellowish brown

36. Senecio tenuifolius

b. Leaf lobes linear-oblong, not spreading; capitula on short and stout peduncle; pappus white

37. Senecio tetrandrus

29a. Leaves small, pinnatifid; segments few, short, acute, margins thickened, often recurved; base not auricled; pappus red

15. Senecio hohenackeri

b. Leaves large, polymorphoss, oblong 10 ovate-lanceolate 10 orbicular-ovate, rhomboid, serrate to deeply lobulate, sessile,to shortly petioled, auriculate or exauriculate; pappus white to pale yellow

30

30a. Annual dwarf herbs, densely greyish pubescent; leaves ovate-lanceolate, serrate; capitula on long, slender, capillary peduncle; involucral bracts triangular, hairy with white scarious margins; achenes pubescent

14. Senecio hewrensis

b. Suffruticose, glabrous undershrubs; leaves oblong to obovate, serrate, broadly amplexicaul at the base; capitula on short peduncle; involucral bracts scaly; achenes striate and hispidulous

39. Senecio vestitus

31a. Shrubs; leaves blackish, elliptic-lanceolate, mucronately serrate. densely reddish pubescent on the lower surface

34. Senecio rhabdos

b. Herbs or undersbrubs; leaves green to dark brown, linear-oblong, ovate, subrotund, rhomboid, serrate, toothed, deeply white to grey tomentose or densely adpresaed glandular hispid

32

32a. Leaves ovate-oblong, pinnatipartite, glabrous or pubescent, petioled; capitula small, rumerous, in terminal corymb; ray florets short

33

b. Leaves linear to linear-lanceolate, ovate, subrotund, rhomboid, entire or deeply lobed or pinnatisect, glabrous or densely adpressed glandular hispid or white to grey tomentose; capitula large, few in terminal corymb; ray florets long

34

33a. Involucre cylindrical; ray florets inconspicuous

12. Senecio graciliflorus

b. Involucre campanulate; ray florets conspicuous

35. Senecio royleanus

34a. Leaves linear to linear-lanceolate, blackish brown, white villous on the midrib, entire, sessile, uniformly arranged on the stems; capitula 1 - 6, terminal, with very long ray florets

22. Senecio lawsoni

b. Leaves ovate, oblong, lanceolate or subrotund, rhomboid, glandular hispid or while to grey adpressed tomentose, short petioled, entire to deeply lobed or pinnatisect; capitula few in terminal corymb; ray florets not very long

35

35a. Leaves ovate to subrotund, densely adpressed glandular hispid on upper surface; lower surface with prominent dark brown venation, margins thickened, mucronately dentate or sometimes pinnatisect Into 2-3 lateral lobes

25. Senecio ludens

b. Leaves oblong, lanceolate, rhomboid, densely white tomentose or grey adpressed tomentose on the lower surface, with prominent venation, margins entire, toothed or deeply lobed

36

36a. Pappus present in both ray and disc florets

37

b. Pappus present only in disc florets or completely lacking

40

37a. Leaves elliptic to linear-lanceolate with prominent midrib

7. Senecio dalzellii

b. Leaves lanceolate, ovate-lanceolate to rhomboid, venation prominent, brown

38

38a. Leaves lanceolate, acuminate, blackish brown on upper surface

26. Senecio mayurii

b. Leaves ovate-oblong to rhomboid, obtuse, greenish brown on upper surface

39

39a. Achenes 2.5 mm long, glabrous to sparsely puberulous; pappus of pale white, scabrid hairs

11. Senecio gibsoni

b. Achenes 4 mm long, pubescent; pappus of white hairs, not scabrid

10. Senecio edgeworthii

40a. Achenes of rayflorets epappose and of disc florets pappose; pappus hairs paleaceous

4. Senecio bombayensis

b. Achenes of ray florets and disc florets both epappose

2. Senecio belgaumensis

41a. Scandent shrubs; glabrous to puberulous or densely white tomentose; leaves ovate to ovate lanceolate, acuminate; petioles auriculate

42

b. Climbing or straggling herbs, glabrous or pubescent; leaves elliptic-lanceolate, acute to acuminate; petioles exauriculate

41. Senecio wightianus

42a. Leaves ovate, densely white tomentose beneath; petioles with densely white tomentose, small, reniform auricles

5. Senecio candicans

b. Leaves ovale-lanceolate, glabrous to floccose grey tomentose beneath; auricles large, foliaceous, glabrous to puberulous

16. Senecio intermedius

List of Lower Taxa