Leaves alternate, simple, margins entire, toothed or variously lobed, reducing in size up stem, mostly pinnately veined; petiolate or sessile and base often auriculate; stipules usually absent.
Heads terminal, solitary or few to many in corymbose panicles; involucral bracts 1-seriate with small bracteoles usually present at base of involucre; receptacle flat to convex, usually without scales, sometimes pitted. Heads usually with numerous florets; either all florets tubular and bisexual, or outer filiform and female and inner tubular and bisexual, or outer ray florets female with yellow, pink or white ligules and inner disc florets tubular and bisexual. Anthers obtuse to shortly tailed at base. Style branches filiform, truncate.
Achenes ± terete, often ribbed, usually with short appressed hairs along ribs and/or grooves; pappus of slender hairs, usually not persistent.
| | Key to the species | |
| 1 | Heads non-radiate; either all florets tubular and bisexual or outer florets filiform and female and inner florets tubular and bisexual | 2 |
| Heads radiate; marginal florets female with usually conspicuous and spreading ligules; disc florets bisexual, more numerous than the female florets | 20 |
| 2 | Involucral bracts regularly 5–9, rarely 10 or 11 in some but not all heads; florets usually 8–25, rarely to 40 | 3 |
| Involucral bracts regularly more than 10; florets 25–70, rarely less
Back to 1 | 10 |
| 3 | Most leaves less than 5 cm long; florets 20–40, outer florets with ligules 1–2 mm long | Senecio glossanthus |
| Most leaves more than 5 cm long; florets 8–25; ray florets absent
Back to 2 | 4 |
| 4 | Leaves pinnatisect to 2-pinnatisect into filiform or linear segments | 5 |
| Leaves not deeply divided into narrow segments, margins either entire or toothed or incised into broad lobes
Back to 3 | 6 |
| 5 | Most leaves bipinnatisect, segments flat, mostly 1.5–3 mm wide; florets exserted only slightly beyond involucre at anthesis; coast and tableland species | Senecio bipinnatisectus |
| Most leaves pinnatisect, segments more or less terete, mostly 1–1.5 mm wide; florets exserted 3–5 mm beyond involucre at anthesis; western species
Back to 4 | Senecio anethifolius |
| 6 | Leaves pinnatifid, lobes usually 1–5 each side, broad and margins more or less toothed | 7 |
| Leaves not lobed, margins entire or toothed
Back to 4 | 8 |
| 7 | Leaves with acute lobes, both surfaces glabrous or softly hairy, green | Senecio biserratus |
| Leaves with rounded lobes, both surfaces more or less bristly, lower surface purplish
Back to 6 | Senecio picridioides |
| 8 | Outer florets filiform and female, inner florets tubular and bisexual; florets exserted 0–2.5 mm beyond involucre at anthesis; chiefly coastal and tableland species, also on the Western Slopes | 9 |
| Florets all tubular and bisexual, exserted 3–5 mm beyond involucre at anthesis; western plains species
Back to 6 | Senecio cunninghamii |
| 9 | Leaves on stems lanceolate to narrow-elliptic, usually 10–30 mm wide, margins regularly and finely toothed, base stem-clasping with retrorse auricles; bracteoles 2 or 3 | Senecio minimus |
| Middle leaves on stems more or less oblanceolate to linear, 2–10 mm wide, margins irregularly and coarsely toothed to entire, base not distinctly stem-clasping, auricles absent or present; bracteoles more than 3
Back to 8 | Senecio diaschides |
| 10 | Involucral bracts usually 18–23; florets 50–70, all tubular and bisexual | Senecio vulgaris |
| Involucral bracts usually 11–13, rarely 14 or 15 in some heads; florets mostly 25–55, rarely to 70 or 12–20, outer florets filiform and female, inner florets tubular and bisexual
Back to 2 | 11 |
| 11 | Middle leaves pinnatisect to bipinnatisect, lobes regularly less than 4 mm wide and more than 10 mm long | 12 |
| Middle leaves entire or variously toothed or if lobed leaves pinnatifid and lobes mostly more than 4 mm wide and less than 10 mm long
Back to 10 | 13 |
| 12 | Leaves and stems glabrous or sparsely cottony-haired when young; leaves runcinate-pinnatisect, the lobes retrorse | Senecio runcinifolius |
| Leaves and stems scabrous; leaves pinnatisect to bipinnatisect, lobes more or less at right angles to midrib
Back to 11 | Senecio hispidulus |
| 13 | Leaves entire or margins finely and regularly toothed; achenes 2–4 mm long | 14 |
| Leaves usually coarsely and irregularly toothed, incised or irregularly lobed; achenes 1.2–2.7 mm long
Back to 11 | 18 |
| 14 | Most leaves linear to more or less lanceolate or narrow-elliptic, lower surface more or less whitish or green, without a distinct petiole; involucral bracts 6.5–9 mm long | 15 |
| Most leaves narrow-oblanceolate to obovate or more or less elliptic, lower surface usually purplish, tapering into a distinct petiole-like base; involucral bracts 5.5–7 mm long
Back to 13 | 17 |
| 15 | Leaves more than 8 mm wide, base auriculate | Senecio minimus |
| Leaves less than 8 mm wide, base not prominently auriculate
Back to 14 | 16 |
| 16 | Plants mostly whitish, densely hairy; hairs on the leaves and stems without a multicellular base, long and slender, closely appressed to the surface; achenes slender, 2.5–4 mm long, beaked | Senecio quadridentatus |
| Plants usually green, more or less hairy; hairs on leaves and stems with a multicellular base, the long slender apices not appressed; achenes plump, 2.2–2.5 mm long, not beaked
Back to 15 | Senecio tenuiflorus |
| 17 | Middle and lower leaves 10–25 mm wide; chiefly in alpine and subalpine regions | Senecio gunnii |
| Leaves mostly 2–10 mm wide, sometimes basal leaves to 15 mm wide; widespread from the coast to the Western Slopes
Back to 14 | Senecio prenanthoides |
| 18 | Leaves with upper surface sparsely cobwebby to glabrescent; involucre usually cobwebby | Senecio glomeratus |
| Leaves with upper surface more or less scabrous, hairs mainly short and tuberculate; involucre glabrous or glabrescent
Back to 13 | 19 |
| 19 | Inflorescence corymbose with more than 50 heads, at first compact; involucral bracts 4–5 mm long; common and widespread species | Senecio hispidulus |
| Inflorescence an open racemose cyme of 4–16 heads; involucral bracts 8–9 mm long; not common, confined to the southern tablelands
Back to 18 | Senecio sp. N sensu Harden (1992) |
| 20 | Ligules of ray florets bright pink to purple | Senecio elegans |
| Ligules of ray florets yellow or whitish
Back to 1 | 21 |
| 21 | Involucral bracts 5–14, rarely more in some heads | 22 |
| Involucral bracts more than 14, rarely some heads with 12–14
Back to 20 | 38 |
| 22 | Involucral bracts less than 10 | 23 |
| Involucral bracts 10–14, rarely more in some heads
Back to 21 | 24 |
| 23 | Leaves more or less circular or broad-ovate, palmately lobed and veined; ligules 8–10 mm long | Senecio tamoides |
| Leaves lanceolate to broad-lanceolate, margins entire, toothed or pinnately lobed, venation pinnate; ligules 1–2 mm long
Back to 22 | Senecio glossanthus |
| 24 | Middle stem leaves sessile, stem-clasping, not tapered into a petiole-like base, more or less cordate with distinct auricles | 25 |
| At least middle stem leaves petiolate or with petiole-like base, auricles absent or if present not broad
Back to 22 | 28 |
| 25 | Lower surface of leaves and stems silvery-woolly | Senecio garlandii |
| Lower surface of leaves and stems glabrous
Back to 24 | 26 |
| 26 | Involucral bracts 5–7 mm long; ligules 5–8 mm long; achenes 2–4 mm long; coastal, tablelands and Western Slopes species | 27 |
| Involucral bracts 7–10 mm long; ligules 8–15 mm long; achenes 5–6 mm long; western plains species
Back to 25 | Senecio magnificus |
| 27 | Bracteoles usually not present at base of involucre | Senecio velleioides |
| Bracteoles present at base of involucre, usually 6–10 (subsp. lanceolatus)
Back to 26 | Senecio lautus |
| 28 | Involucral bracts 3–6 mm long; ligules 3–7 mm long or rarely to 9 mm long and then leaves lyrate-pinnatifid or bipinnatisect | 29 |
| Involucral bracts 6–10 mm long; ligules mostly 10–20 mm long, occasionally 8–10 mm long and then leaves neither lyrate-pinnatifid nor bipinnatisect
Back to 24 | 33 |
| 29 | Inflorescence of solitary heads; leaves 2–3 cm long and 1–2 mm wide | Senecio behrianus |
| Inflorescence corymbose, heads few to numerous; leaves mostly more than 3 cm long and more than 2 mm wide or with at least some leaves pinnatifid or pinnatisect
Back to 28 | 30 |
| 30 | Leaves lyrate-pinnatifid or bipinnatisect | Senecio jacobaea |
| Leaves neither lyrate-pinnatifid nor bipinnatisect
Back to 29 | 31 |
| 31 | Disc florets more than 12; leaves either linear to spathulate or obovate or more or less lanceolate or elliptic and 1–25 mm wide, or pinnatifid or pinnatisect, mostly less than 7 cm long | Senecio lautus |
| Disc florets 8–12; leaves linear to lanceolate and elliptic or obovate, 5–40 mm wide and usually more than 7 cm long
Back to 30 | 32 |
| 32 | Lower surface of leaves glabrous and usually strongly glaucous; ray florets 7–9 | Senecio linearifolius var. dangarensis |
| Lower surface of leaves either cobwebby or glabrous and then not glaucous; ray florets usually 4–6, rarely more
Back to 31 | Senecio linearifolius |
| 33 | Involucral bracts fused except at apices; ligules 15–20 mm long; leaves linear, entire | Senecio gregorii |
| Involucral bracts free for most of their length; ligules 8–13 mm long; leaves with margins toothed to more or less pinnatifid or pinnatisect
Back to 28 | 34 |
| 34 | Perennial herbs or shrubs, erect, mostly 60–150 cm high; leaves more or less ovate to elliptic, not more or less fleshy | 35 |
| Rhizomatous perennial or annual herbs, stems prostrate, decumbent or more or less erect, 10–50 cm high; leaves pinnatifid or more or less oblanceolate to spathulate, more or less fleshy
Back to 33 | 36 |
| 35 | Leaves regularly toothed; petiole distinct; ligules 10–13 mm long | Senecio amygdalifolius |
| Leaves irregularly toothed or lobed, base tapered and more or less petiole-like; ligules c. 10 mm long
Back to 34 | Senecio vagus |
| 36 | Leaves mostly crowded at base of stem; heads 2–5 on scape up to 25 cm long | Senecio leptocarpus |
| Leaves scattered along stems; heads usually 1–20 in corymbs, peduncles mostly 2–10 cm long
Back to 34 | 37 |
| 37 | Leaves 4–8 cm long, pinnatifid; species of western plains | Senecio platylepis |
| Leaves 1–3 cm long, margins toothed to entire; species of seashores
Back to 36 | Senecio spathulatus var. attenuatus |
| 38 | Involucral bracts less than 7 mm long | 39 |
| Involucral bracts more than 7 mm long
Back to 21 | 42 |
| 39 | Lower surface of leaves whitish, densely cobwebby; bracteoles at base of involucre 12–18 | Senecio pterophorus |
| Lower surface of leaves green, more or less glabrous; bracteoles at base of involucre 3–11
Back to 38 | 40 |
| 40 | Achenes 5–6 mm long, papillose, prominently beaked and often curved; pappus persistent, about same length as achene | Senecio tuberculatus |
| Achenes 1.5–2.7 mm long, glabrous or hairy, neither beaked nor curved; pappus not persistent, at least twice as long as achene
Back to 39 | 41 |
| 41 | Involucral bracts usually 20 or 21; leaves narrow-lanceolate to oblanceolate with margins entire, variously toothed or rarely more or less pinnatifid; chiefly coastal divisions, also to Western Slopes | Senecio madagascariensis |
| Involucral bracts usually 15–18; leaves linear and entire or more commonly variously pinnatisect; mostly in inland divisions (subsp. dissectifolius)
Back to 40 | Senecio lautus |
| 42 | Plants silvery-woolly | Senecio crassiflorus |
| Plants glabrous to sparsely hairy
Back to 38 | 43 |
| 43 | Ligules 15–25 mm long | Senecio macranthus |
| Ligules 6–15 mm long
Back to 42 | 44 |
| 44 | Leaves glaucous, more or less oblanceolate with margins toothed to entire, stem-clasping with base more or less cordate and auriculate | Senecio magnificus |
| Leaves not glaucous, more or less linear to oblanceolate with margins entire or rarely toothed, or pinnatifid or pinnatisect, base not as above
Back to 43 | 45 |
| 45 | Leaves more or less oblanceolate to linear, margins entire or rarely irregularly toothed | Senecio daltonii |
| Leaves either pinnatifid to pinnatisect or margins irregularly toothed or lobed
Back to 44 | 46 |
| 46 | Herbs 10–50 cm high; most leaves regularly pinnatifid | 47 |
| Herb or shrub 60–120 cm high; upper leaves more or less toothed, lower leaves pinnatisect with 1–6 irregular lobes
Back to 45 | Senecio vagus |
| 47 | Leaves scattered up stem; heads usually 3–20 in a leafy corymb; arid and semi-arid regions | Senecio platylepis |
| Leaves mostly in a basal rosette; heads solitary on scape to 25 cm long; confined to alpine areas
Back to 46 | Senecio pectinatus |
