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Book cover - Common Weeds of New ZealandAn Illustrated Guide to
Common Weeds
of New Zealand


Senecio jacobaea


Reproduced from
Common Weeds of New Zealand
by Ian Popay, Paul Champion & Trevor James
ISBN 0 473 09760 5
by kind permission of the
New Zealand Plant Protection Society

Publication or other use of images or descriptive text on these pages is unauthorised unless written permission is obtained from the authors and publisher.
Appropriate acknowledgement of the publication Common Weeds of New Zealand must always be given.

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Senecio jacobaea - ragwortRosette-based, robust biennial or perennial with characteristic unpleasant smell when bruised. Leaves dissected into large lobes. Flower stem up to 1.2 m tall, bearing bright yellow composite flowers, each 2 cm across, in flat-topped clusters.

  • Flowers Golden-yellow, about 2 cm in diameter, with golden-yellow disk florets, and about twelve yellow ray florets, in compact flat-topped terminal inflorescences. Flowers Nov-Apr.
  • Fruit Rounded achenes about 2 mm long, with a pappus of simple hairs up to 5 mm long, not forming a 'clock'.
  • Leaves Rosette of dark green, pinnately lobed leaves 4-8 cm long with large blunt terminal lobes. Stem leaves deeply cut, stalkless, clasping the stem, with no broad terminal lobes. Leaves often with purple colouring on the underside.
  • Stems Purplish, erect, ridged, densely woolly towards the top, becoming smooth lower down. Stems leafy, branching, 50-120 cm tall.
  • Roots Fibrous.


Pastures, waste places, open forest, swamps and river-beds.


Weed of cattle pastures throughout New Zealand where annual rainfall exceeds 800 mm, also in the Chatham Islands, but eradicated from the Kermadecs. Originally from Europe and western Asia.


The plant forms a rosette in its first year, and usually flowers and then dies in its second year, unless its growth is interfered with, when it can become a multi-crowned perennial. Poisonous to cattle and horses, but less so to sheep. Usually ignored by cattle and horses but kept in check by sheep. The poison affects the liver, can be very slow acting in sheep and its effects can be confused with those of facial eczema. Several insects have been brought into NZ in attempts to control this species. Currently, the ragwort flea beetle (Longitarsus jacobaea) is looking very promising. Ragwort is subject to Pest Plant Management Strategies in most regions of NZ. Details are available from individual regional councils or unitary authorities. Has been regarded as noxious in NZ since 1900.

Related species

Marsh ragwort (Senecio aquaticus) is shorter, with more open inflorescences, less-dissected leaves and less hairy achenes. It flowers Jan-Jun, and is found in wet-lying areas at Mercer and Levin in NI, and in Nelson Province and Southland in SI.

Derivation of botanical name

Senecio (Lat.) = old man, from the fluffy white seed heads; jacobaea from St. James (Jacobus), one of the Twelve Apostles.


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Web-notes: Weed Links

On this site

Reproduced from Common Weeds of New Zealand:

External Links

WeedbustersWeedbusters New Zealand
Weedbusters is a weeds awareness and education programme that aims to protect New Zealand's environment from the increasing weed problem.
A free tool to assist farmers and agricultural professionals in decision-making regarding weed and pest identification, biology, impact and management.
Weed keyNew Zealand Weeds Key
An interactive identification key to the weeds of New Zealand. Developed at Landcare Research.

New Zealand Plant Conservation Network naturalised plants
Search for information on more than 2500 naturalised and weedy plants.
NZ Plant Protection SocietyNew Zealand Plant Protection Society
Their main objective: "To pool and exchange information on the biology of weeds, invertebrate and vertebrate pests, pathogens and beneficial organisms and methods for modifying their effects."
Massey UniversityMassey University Weeds Database
A site providing information about New Zealand weeds and weed control. It has a series of pages showing pictures of New Zealand weeds, notes on identification and control. It also provides information on a university paper entitled Controlling Weeds.

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Last updated: March 1, 2021