Scientific name: Senecio jacobaea L.
Erect perennial to 1.5m (often much shorter), very variably pubescent.
Leaves deeply pinnately lobed, the lowest lobes ± clasping stem.
Stem-leaves with several pairs of lateral lobes and terminal lobe not much larger.
Ligules 12-15, 5-9mm (rarely shorter), rarely absent (Senecio jacobaea L. var. nudus Weston), yellow.
Achenes of disc flowers pubescent.
Chromosome number: 2n=40.
Native; grassland, waysides, waste ground, sand-dunes.
Common throughout British Isles.
This species is keyed out on Page 1060 in the Text Key.
Very variable; dwarf coastal plants with dense web-like pubescence and without ligules have been called Senecio jacobaea L. subsp. dunensis (Dumort.) Kadereit & P.D. Sell, but represent only 1 line of variation.
- Senecio x albescens Burb. & Colgan (= Senecio cineraria x Senecio jacobaea) occurs ± throughout the range of naturalized Senecio cineraria in British Isles and (from cultivated Senecio cineraria) scattered North to Dunbarton; it is intermediate in pubescence, leaf-shape and habit but has pubescent disc-achenes as in Senecio jacobaea. It is fertile and backcrosses, forming a range of intermediates.
- Senecio x ostenfeldii Druce (= Senecio jacobaea x Senecio aquaticus) occurs throughout much of Britain and Ireland, more commonly in West, with the parents; it is intermediate in leaf dissection, achene pubescence and inflorescence shape. It is less than 15% fertile but backcrosses and sometimes forms hybrid swarms.