Jacobaea vulgaris Gaertn.

Erect biennial or perennial herb, 30–120 cm tall. Stems densely lanate above but soon glabrous, usually branched only above, sometimes branched from base. Basal lvs lanate when young, usually becoming almost glabrous but often remaining hairy on veins of lower surface, rarely sparsely to moderately hairy on both surfaces, petiolate; petiole < lamina, amplexicaul; lamina lyrate-pinnatifid, obovate to ovate-oblong, obtuse to subacute at apex, (3)–5–20–(25) × (2)–4–6–(8) cm; segments ovate, oblong, or obovate, 1–2-pinnatisect; venation pinnate. Cauline lvs lyrate-pinnatifid to 1-pinnate; segments again 1–2-pinnatisect; uppermost lvs apetiolate, with narrow segments. Capitula usually numerous in dense, flat-topped corymbs, rarely fewer and more diffuse. Supplementary bracts 3–10, lanceolate, 1.5–3 mm long. Involucral bracts 11–14, ovate-oblong, 3–5 mm long, usually glabrous, sometimes with a few scattered hairs. Ray florets 11–13; ligules bright yellow, 5–12 mm long. Disc golden yellow. Achenes terete, 1.4–2.5 mm long, those of ray florets glabrous, those of disc florets moderately hairy; pappus 3.5–5 mm long, soon deciduous from ray achenes.

[From: Webb et al. (1985) Flora of New Zealand. Volume 4 as Senecio jacobaea L.]