Weed Seed: Senecio inaequidens (South African ragwort)
Invasive Plant - South African Ragwort (Senecio inaequidens)
South African ragwort
Prohibited Noxious, Class 1 in the Canadian Weed Seeds Order, 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.
Canadian: Absent from Canada (Brouillet et al. 2016Footnote 1).
Worldwide: Native to southern Africa and introduced to many European countries and Taiwan (CFIA 2014Footnote 2). Reports from Mexico and parts of South America may refer to Senecio madagascariensis (CFIA 2012Footnote 3).
Duration of life cycle
Seed or fruit type
- Achene length: 2.0 - 3.0 mm
- Achene width: 0.2 - 0.5 mm
- Oblong-shaped achene with a narrow top
- Achene has several longitudinal ribs; surface is roughened, appears sparkling under lights
- Achene usually dark brown, may be light brown or green in immature specimens
- Achene surface between the ribs is densely covered with worm-like white hairs
- Immature achenes have a long, white pappus 2-3 times the length of the achene
Habitat and crop association
Colonizes a wide range of open ruderal habitats, as well as stream banks, coastal dunes, grasslands, vineyards and pastures (CFIA 2012Footnote 3).
Historic introduction sites of South African ragwort in Europe were closely tied with the wool industry (CABI 2016Footnote 4). Pastures that contain South African ragwort produce lower quality forage due to the poisonous alkaloids in the plant (Dimande et al. 2007Footnote 5).
This species produces thousands of seeds per year that can be carried by water, hay, humans or machinery into new habitats (CABI 2016Footnote 4, Heger and Böhmer 2006Footnote 6).
Common groundsel (Senecio vulgaris)
- Similar size, oblong shape, and surface hairs.
- Common groundsel tends to be sharply narrowed at both ends; South African ragwort is narrowed at one end. The surface hairs of common groundsel are short and sparse; the hairs of South African ragwort are longer and more dense.
Madagascar ragwort (Senecio madagascariensis)
- Similar oblong shape, rough texture, surface hairs, and is closely related to South African ragwort.
- Madagascar ragwort achenes are generally shorter than South African ragwort (2.0 - 2.5 mm long), both ends of achenes narrowed, usually red brown with short white hairs on the ribs.
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