Senecio sect. Crociseris (Reichenbach) Boissier, 1844

Calvo, Joel, Álvarez, Inés & Aedo, Carlos, 2015, Systematics of Senecio section Crociseris (Compositae, Senecioneae), Phytotaxa 211 (1), pp. 448-450 : 448-450

Key to species of Senecio sect. Crociseris

1. Cauline leaves not strongly decreasing in size up the stem; basal and lower cauline leaves usually withering at flowering time........................................................................................................................... .............................................................. 2

- Cauline leaves decreasing in size up the stem; basal and lower cauline leaves usually remaining at flowering time, at least the lower cauline leaves ......................................................................................................................................................... 5

2. Involucral bracts (10–)12–13(–14) ................................................................................................................... S. doriiformis

- Involucral bracts (15–)20–22(–30) ........................................................................................................................................ 3

3. Cauline leaves sessile, glabrescent to lanate beneath, slightly discolorous; stem fistulous................................ S. paludosus

- Cauline leaves attenuated into a petiole, usually glabrescent beneath, concolorous; stem solid........................................... 4

4. Supplementary bracts 6.3–13.8 mm long; capitula 1(–3) ........................................................................... S. transylvanicus

- Supplementary bracts 2.5–7.5 mm long; capitula (1–)4–7(–21)....................................................................... S. pyrenaicus

5. Stem subscapose; basal leaves succulent in a dense rosette.................................................................................. S. auricula

- Stem leaved; basal leaves neither succulent nor in a dense rosette........................................................................................ 6

6. Basal leaves cordate, sometimes truncate; cauline leaves amplexicaul-auriculate................................................................ 7

- Basal leaves attenuate to rounded, rarely subcordate; cauline leaves attenuate to semiamplexicaul .................................... 9

7. Supplementary bracts 3–8; achenes 7.6–9.8 mm long............................................................................................... S. olgae

- Supplementary bracts 10–16; achenes 3.3–5.6 mm long ....................................................................................................... 8

8. Basal leaves reniform, with scattered scabrid-arachnoid trichomes to slightly lanate beneath; achenes with scattered intercostal trichomes........................................................................................................................................... S. perralderianus

- Basal leaves ovate, glabrous beneath; achenes with dense intercostal trichomes......................................... S. trapezuntinus

9. Leaves with persistent ± lanate indumentum .......................................................................................................... S. cilicius

- Leaves glabrescent or with a dense arachnoid-floccose indumentum, tending to be caducous .......................................... 10

10. Involucre whitish, densely arachnoid-floccose to lanate......................................................................................................11

- Involucre greenish, glabrescent to arachnoid-floccose ........................................................................................................ 15

11. Synflorescence bracts ovate-lanceolate.................................................................................................................. S. eubaeus

- Synflorescence bracts linear-oblong .................................................................................................................................... 12

12. Supplementary bracts (6–)9–10(–16); achenes with intercostal trichomes that are denser towards the apex ...... S. tauricola

- Supplementary bracts (7–)13–20(–44); achenes glabrous or nearly so, sometimes with scattered intercostal trichomes .. 13

13. Basal leaves ovate to elliptic, sometimes lanceolate (ratio basal leaf width / basal leaf length = 0.44–1.12), ± discolorous; leaf-base usually rounded to subcordate; apex of involucral bracts slightly violet coloured with a black spot at the summit. ................................................................................................................................................................................. S. eriopus

- Basal leaves lanceolate to oblanceolate, rarely obovate (ratio basal leaf width / basal leaf length = 0.15–0.68), ± concolorous; leaf-base usually attenuate; apex of involucral bracts greenish or blackish ................................................................. 14

14. Supplementary bracts ± imbricated; involucral bracts smooth, usually without a black spot; ligulate florets pale yellow; capitula 1(–3)........................................................................................................................................................... S. scopolii

- Supplementary bracts not imbricated; involucral bracts 0–2-keeled, usually with a black spot; ligulate florets yellow to orange; capitula 1–4(–9).................................................................................................................................... S. doronicum