Jacobaea vulgaris
Environmental Weed (2024)
Common names
ragwort
Biostatus
Exotic
Conservation status
Not applicable
Category
Vascular
Structural class
Herbs - Dicotyledonous composites
Flower colours
Yellow
Detailed description
Erect biennial or perennial herb, 30~120cm tall. Stems densely lanate above but soon glabrous, usu. branched only above, sometimes branched from base. Basal leaves lanate when young, usu. 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, 5~20 x 4~6cm; segments ovate, oblong or obovate, 1~2-pinnatisect; venation pinnate. Cauline leaves lyrate-pinnatifid to 1-pinnate; segments again 1~2-pinnatisect; uppermost leaves apetiolate, with narrow segments. Capitula usu. numerous in dense flat-topped corymbs, rarely fewer and more diffuse. Supplementary bracts 3~10, lanceolate, 1.5~3mm long. Involucral bracts 11~14, ovate-oblong, 3~5mm long, usu. glabrous, sometimes with a few scattered hairs. Ray florets 11~13; ligules bright yellow, 5~12mm long. Disc golden-yellow. Achenes terete, 1.4~2.5mm long, those of ray florets glabrous, those of disc florets moderately hairy; pappus 3.5~5mm long, soon deciduous from ray achenes. (-Webb et. al., 1988)
Similar taxa
An erect herb that commonly grows to a height of 45-60cm; can grow up to 1.6m. Bright yellow flowers with golden yellow disc (Webb et al., 1988). It is distinguished from the related Jacobaea aquatica by the more dissected leaves, the usually flat-topped dense flowers and hairy disc achenes (1-seed fruit). Stems are reddish/purple at the base and branch out at the top. The leaves are deeply divided and wrinkled, dark green on top with a paler green, downy lining.
Habitat
Terrestrial. Especially abundant in areas of higher rainfall (Webb et al.,1988). Plant of open ground and light gaps: wherever there is sufficient bare ground for seeds to germinate and establish. Found mostly in open forests, riverbeds, swamps and pastures. Grows on coastal slopes and along tracks (West,1996).
Detailed taxonomy
Genus
Family
Synonyms
Senecio jacobaea
Endemic family
No
Ecology
Flowering
November, December, January, February, March, April
Year naturalised
1894
Origin
Europe, W Asia
Reason for introduction
Accidental
Life cycle and dispersal
Biennial or Perennial herb. In autumn, the flowering stems die back and in undisturbed situations the whole plant may die. In the first year of growth a basal rosette is produced and in the second year yellow flowers are produced at the top of the flowering stem which grows from the centre of the rosette (West,1996). Reproduces from crowns, roots and seeds. A well developed multi-stemmed plant is estimated to produce 250,000 seeds a year (80% may be viable). Dispersal of seed via water, animals, vehicles, clothing, hay, chaff. Numerous small seeds are dispersed widely by the wind (West,1996).
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
FACU: Facultative Upland
Occasionally is a hydrophyte but usually occurs in uplands (non-wetlands).
Other information
Environmental Weed (2024)
This plant is named in a list of 386 environmental weeds in New Zealand 2024 prepared by DOC. 759 candidate species were considered for inclusion on this new comprehensive list of environmental weeds in New Zealand. The species considered were drawn from published lists of weed species, lists of plants that must be reported or managed by law if observed, existing national and regional programmes and agreements for pest management, and species already managed by the Department of Conservation (DOC). Candidate species were then assessed to see if they were fully naturalised and whether they have more than minor impacts in natural ecosystems. Read the full report here.
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
JACVUL
Referencing and citations
References and further reading
Pelser PB, Veldkamp J-F, van der Meijden R. 2006. New combinations in Jacobaea Mill. (Asteraceae - Senecioneae). Compositate Newsletter 44: 1-11.