Weed Seed: Inula britannica (British yellowhead)
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.
Canadian: Occurs in ON and QC (Brouillet et al. 2016Footnote 1).
Worldwide: Native to Europe and temperate Asia. Introduced to Canada and the United States (NY, DC). May be an occasional escape rather than truly established in North America (eFloras 2016Footnote 2).
Duration of life cycle
Seed or fruit type
- Achene length: 1.0 - 1.5 mm
- Achene width: 0.2 - 0.5 mm
- Pappus length: 4.0 - 6.0 mm
- Achene is oblong with flat ends
- Surface of achene has several longitudinal ribs, is rough and covered with thin white hairs
- Achene is medium brown
- Pappus hairs are barbed, appear to be persistent.
- Thin, distinctive ring of white tissue at the base of the achene.
Habitat and Crop Association
Wet places (e.g., streambanks, ditches, marshes, wet woods and grasslands), nurseries, roadsides and waste places (FNA 1993+Footnote 3, CABI 2016Footnote 4). Its roots and rhizomes are known to contaminate Hosta spp. root systems (CABI 2016Footnote 4).
Introductions of British yellowhead into Canada and the eastern United States started in approximately the 1920s and have mostly occurred through the nursery trade. Populations either did not persist or are small and contained (Lehtonen and Schall 2000Footnote 5).
In the Netherlands, where this species is known to be associated with Hosta spp., it has been subject to aggressive control since 2000 (Lehtonen and Schall 2000Footnote 5).
Common groundsel (Senecio vulgaris)
- Similar size, oblong shape, hairs on surface as British yellowhead.
- The surface hairs of common groundsel are short and thick; the hairs of British yellowhead are longer and thin. Common groundsel does not have a white ring of tissue at the base of the achene.
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