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Ragwort - Identification | LC0180 |
Department of Primary Industries, Frankston
October 2004 |  |
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This Landcare Note describes the weed ragwort, Senecio jacobaea.
See the Landcare Note LC0382: Ragwort - management for information about the management of this weed.
Common and scientific names
Ragwort Senecio jacobaea Linnaeus
Family Asteraceae (daisies)
Figures 1-4. Left: mature plant; top right: cabbage; middle right: rosette; bottom right: seedlings.
Figures 5, 6. Flowers; disc seed with pappus, and ray seed.
Figure 7. Ragwort infestation.
Figure 8. Portion of plant showing stem leaves and upper roots.
Description
A biennial or perennial herb (rarely an annual) reproducing from crowns, roots and seeds.
Stems – usually one, sometimes several per plant; erect, up to 1.8 m high, more commonly 45 to 60 cm; rigid, reddish to purple at base, branched at top, furrowed, sometimes bearing cobweb-like hairs.
Leaves – dark to mid-green on upper surface, paler and sometimes downy underneath, up to 35 cm long, deeply divided and wrinkled; rosette leaves stalked, stem leaves unstalked, base of upper stem leaves with ear-like lobes around the stems; young leaves sometimes covered with cobweb-like hairs. The lower leaves die off as the flowering stalk emerges.
Flowers – bright yellow, daisy-like, about 2.5 cm in diameter with 12 to 15 ligulate florets (bearing strap-like ‘petals’) and 30 to 50 tubular (disc) florets.
Seeds – commonly 70,000 but up to 250,000 per plant; straw coloured to light brown, about 2 mm long and 0.5 mm wide; up to 75 per flower. Each flower has two types of seed: disc seeds (40-60/flower), in the centre of the flower, have a pappus of fine, white, feathery hairs 4 to 5 mm long to aid wind dispersal and a covering of microscopic bristles (trichomes) which aids attachment to animals; ray seeds (12-15/flower) around the outer edge of the flower, are smooth, thicker and heavier than disc seeds, and drop straight to the ground.
Roots – a crown or stout rootstock at or just below the soil surface, with numerous fleshy roots each about 15 cm long and many fibrous roots.
Similar species
Victoria has more than 50 species of Senecio, including 7 naturalised exotic species. Native species are often mistaken for ragwort, which has the following distinctive combination of characters: yellow flowers with 10 to 15 petals 4 to 10 mm long, 11 to 13 black- or brown-tipped bracts around the base of the flower; flowering stems branched, with about 30 to 200 flowers per cluster; leaves hairless or sparsely-haired beneath and lacking broad stem-clasping bases; rosette and stem leaves deeply divided (primary lobes divided almost to the midrib); mature plants mostly lacking rosette leaves; seed pale brown, of two distinct types, one minutely hairy, the other smooth. If in doubt, contact an expert.
Flowering Period
Origin
Europe and western Asia.
Distribution
Figure 9 . Records of ragwort in Victoria.
Lifecycle
In the first year the seedling grows to form a rosette. In year two some plants mature and flower but others may be up to 5 years old before flowering and many die as rosettes. Generally seedlings appear in autumn (mostly) and spring and grow as rosettes until spring of year two, when more-upright foliage (the “cabbage” stage) is produced. Flowering stalks develop later in spring and in summer, with peak flowering from late January through to March. Odd plants may flower at any time. Plants turn brown and die after seed set. Seed can remain viable in the soil for at least 8 years.
Habitat and land use
Humid temperate areas with annual rainfall over 750 mm. Usually found on heavy soils of moderate fertility. Common in poorly managed degraded pastures and in areas cleared in the past but never properly developed for pasture. Also found in natural areas, particularly near the coast. Well established on the Mornington Peninsula and the Strzelecki, Otway and Dandenong Ranges.
Dispersal
Seeds spread by wind, water, animals, farm implements, agricultural produce including hay, and on clothing and other equipment. Most seed falls near the parent plant, but much becomes airborne and travels for long distances. Seed readily floats in water but germinates quickly when immersed.
References
- Jeanes, J.A. (1999) Asteraceae. Pp. 652-984 in N.G. Walsh & T.J. Entwisle (Eds.), Flora of Victoria Volume 4. Dicotyledons Cornaceae to Asteraceae. Melbourne, Inkata Press.
- Parsons, W.T. and Cuthbertson, E.G. (2001) Noxious Weeds of Australia. 2nd Ed., Collingwood, Vic., CSIRO Publishing.
Acknowledgements
Compiled by Ian Faithfull with assistance of David McLaren. Map by John Weiss.
This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
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