Weed Seed: Senecio madagascariensis (Madagascar ragwort)

Family

Asteraceae

Common Name

Madagascar ragwort

Regulation

  • Prohibited Noxious, Class 1 in the Canadian Weed Seeds Order, 2016, 2016 under the Seeds Act. All imported and domestic seed must be free of Prohibited Noxious weed seeds.
  • Listed on the List of Pests Regulated by Canada established under the Plant Protection Act.

Distribution

Canadian: Absent from Canada (Brouillet et al. 2016Footnote 1).

Worldwide: Native to southern Africa and Madagascar and introduced to Argentina, Australia, Colombia, Japan, Kenya, Mauritius, Réunion and the United States (Hawaii) (CFIA 2014Footnote 2).

Duration of life cycle

Short-lived perennial

Seed or fruit type

Achene

Identification features

Size

  • Achene length: 2.0 – 2.5 mm
  • Achene width: 0.5 mm

Shape

  • Achene is oblong with narrow ends

Surface Texture

  • Several longitudinal ribs on achene surface.
  • Surface roughened, appears sparkling under lights.

Colour

  • Achene is dark yellow to reddish-brown

Other Features

  • Short, worm-like white hairs between the ribs of achene.
  • Immature achenes have a long, white pappus 4.0 - 6.5 mm long.

Habitat and Crop Association

Colonizes a wide range of habitats, elevations and soil types. Often found in arid or moist pastures, coastal plains, yards, fields and roadsides (CFIA 2012Footnote 3).

General Information

Madagascar ragwort is a serious pest plant in Australia and Hawaii (Starr et al. 1999Footnote 4). This pioneer plant produces several thousands of seeds every year that are dispersed by wind or water (Starr et al. 1999Footnote 4). Infested pastures suffer lowered productivity through competition and toxicity to livestock (CABI 2016Footnote 5).

Similar species

Common groundsel (Senecio vulgaris)

  • Similar size, oblong shape and narrow ends.
  • The surface hairs of common groundsel are long and dense; Madagascar ragwort has short, sparse hairs.

South African ragwort (Senecio inaequidens)

  • Similar oblong shape, ribs and is closely related to Madagascar ragwort.
  • South African ragwort can be up to 0.5 mm longer than Madagascar ragwort, has only one end narrowed and is usually dark brown and densely covered with long white hairs.

Photos

Figure 1 - Madagascar ragwort (Senecio madagascariensis) achenes
Madagascar ragwort (Senecio madagascariensis) achenes
Figure 2 - Madagascar ragwort (Senecio madagascariensis) achene
Madagascar ragwort (Senecio madagascariensis) achene
Figure 3 - Madagascar ragwort (Senecio madagascariensis) achene, close-up of surface
Madagascar ragwort (Senecio madagascariensis) achene, close-up of surface
Figure 4 - Madagascar ragwort (Senecio madagascariensis) achene, top view
Madagascar ragwort (Senecio madagascariensis) achene, top view

Similar species

Figure 5 - Similar species: Common groundsel (Senecio vulgaris) achenes
Similar species: Common groundsel (Senecio vulgaris) achenes
Figure 6 - Similar species: Common groundsel (Senecio vulgaris) achene, close-up of surface
Similar species: Common groundsel (Senecio vulgaris) achene, close-up of surface
Figure 7 - Similar species: South African ragwort (Senecio inaequidens) achenes
Similar species: South African ragwort (Senecio inaequidens) achenes
Figure 8 - Similar species: South African ragwort (Senecio inaequidens) achene, close-up of surface
Similar species: South African ragwort (Senecio inaequidens) achene, close-up of surface
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