Flora of New Zealand Series

ragwort

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.

N.; S.: throughout, locally common to abundant especially in areas of higher rainfall; K., Ch.

Europe, W. Asia 1894

Mostly waste places and pasture, also riverbeds, open forest, and swamps.

FL Nov-Apr-(Jul).

Poisonous (Connor 1977).

Ragwort is a widespread weed and has attracted particular attention because of its poisonous properties. It is distinguished from the related S. aquaticus by the more dissected lvs, the usually flat-topped, dense infl., and the conspicuously hairy disc achenes. The ecology of the sp. has been reviewed by Wardle, D. A., New Zealand J. Ecol. 10 : 67-76 (1987). The related S. erucifolius L., distinguished by the narrower lf segments and hairy ray achenes, has been recorded for N.Z. but probably in error for S. jacobaea. S. dimorphocarpos Colenso is based on material of S. jacobaea.