Fact Sheets


Pentanema britannicum (L.) D. Gut. Larr. et al.

Family :

Famille :


Synonym(s) :

Synonyme(s) :

Inula britannica L.
Inula japonica Thunb.

Common Name(s) :

Nom(s) commun(s) :

British yellowhead
(English) (GC 2016)
Inule des fleuves (French) (GC 2016)
British elecampane (English) (CABI 2020)
Meadow fleabane (English) (CABI 2020)
Ou ya xuan fu hua (Chinese) (CABI 2020)

  • Pentanema britannicum (British yellowhead) achene with pappus

  • Pentanema britannicum (British yellowhead) achene with pappus

  • Pentanema britannicum (British yellowhead) immature achenes

  • Pentanema britannicum (British yellowhead) base of achene

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Regulation :

Remarques Réglementation:

  • CFIA Weed Seeds Order - Class 1: Prohibited Noxious Weed Seeds
  • USA Federal Noxious Weed List

Regulation Notes:

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.

Distribution :

Répartition :

Native to Europe and temperate Asia, introduced to Canada and the United States (New York, District of Columbia) (CABI 2020). May be an occasional escape rather than truly established in North America (FNA 1993+). Occurs in Ontario and Quebec (Brouillet et al. 2010+).

Habitat and Crop Association :

Habitat et Cultures Associées :

Wet places (e.g., streambanks, ditches, marshes, wet woods and grasslands), nurseries, roadsides and waste places (FNA 1993+; CABI 2020). Its roots and rhizomes are known to contaminate Hosta species root systems (CABI 2020).

Economic Use, cultivation area, and Weed Association :

Utilisation économique, zone de culture et association de mauvaises herbes :

Duration of Life Cycle :

Durée du cycle vital:


Dispersal Unit Type :

Type d’unité de dispersion :


General Information


Introductions of Pentanema britannicum 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 2000).

In the Netherlands, where this species is known to be associated with Hosta species, it has been subject to aggressive control since 2000 (Lehtonen and Schall 2000).




  • Achene


    • Achene length*: 1.0 – 1.5 mm; width: 0.2 – 0.5 mm
    *Note: minimum and maximum of 5 achenes in a normal range of this species using specimen measurement (ISMA 2020)


    • Achene is cylindrical with truncate ends

    Surface Texture

    • Surface of achene has several longitudinal ribs covered with long and thin white hairs


    • Achene is dull medium brown coloured

    Other Features


    • Pappus is persistent when the achene is mature (FNA 1993+)
    • Pappus hairs are long (length : 4.0 – 6.0 mm, FNA 1993+) and dull white coloured
    • Pappus bristles are generally attached by their bases in a ring (FNA 1993+)

    Achene end with pappus

    • A small, thin style remnant is in the center of truncate end surrounded by the pappus

    Achene end without pappus

    • Thin ring of white tissue at one end of the achene
  • Seed


    • Seed size similar to achene size


    • Seed oblong shape

    Surface Texture

    • Seed surface smooth


    • Seed light yellow coloured

    Other Features

    • Seed coat thin, whitish coloured, adhering to the fruit wall
  • Embryo


    • Embryo fills the seed


    • Embryo is spatulate, axial position


    • Endosperm absent, nutritive tissue stored in the cotyledons

    Other Features

    • Embryo is soft-textured

Identification Tips


The long white persistent pappus, long surface hairs and white ring of tissue on the end opposite the pappus are distinguishing features of P. britannicum achenes.

Additional Botany Information



  • Flowers yellow and daisy-like with both disc and ray florets (CABI 2020)

Vegetative Features

  • Can reproduce vegetatively by creeping rhizomes (CABI 2020)

Similar Species


Similar species are based on a study of seed morphology of various species, and those with similar dispersal units are identified. The study is limited by physical specimen and literature availability at the time of examination, and possibly impacted by the subjectivity of the authors based on their knowledge and experience. Providing similar species information for seed identification is to make users aware of similarities that could possibly result in misidentification.

Senecio vulgaris L. (common groundsel)

S. vulgaris achenes are larger (length*: 1.9 – 2.7 mm; width: 0.4 – 0.6 mm) they can be shades of reddish-brown, brown or grey and are narrowed at both ends. Pentanema britannicum achenes are medium brown coloured and do not narrow at the ends. S. vulgaris surface hairs are short and thick; the hairs on P. britannicum achenes are longer and thinner. S. vulgaris achenes do not have a white ring of tissue at the end of the achene opposite the pappus.

*Note: minimum and maximum of 10 achenes in a normal range of this species using image measurement (ISMA 2020)

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Brouillet, L., Coursol, F., Meades, S. J., Favreau, M., Anions, M., Bélisle, P. and Desmet, P. 2010+. VASCAN, the database of vascular plants of Canada. http://data.canadensys.net/vascan/ Accessed October 15, 2020.

Centre for Agriculture and Bioscience International (CABI). 2022. Invasive Species Compendium, CAB International, Wallingford, UK. https://www.cabidigitallibrary.org/journal/cabicompendium Accessed October 13, 2020.

Flora of North America (FNA) Editorial Committee, eds. 1993+. Flora of North America North of Mexico [Online]. 22+ vols. New York and Oxford.  Accessed December 29, 2022

Global Biodiversity Information Facility (GBIF) Secretariat. 2022. https://doi.org/10.15468/39omei Accessed via https://www.gbif.org/species/10010617 Accessed December 29, 2022

Government of Canada (GC). 2016. Canadian Weed Seeds Order. https://laws-lois.justice.gc.ca/eng/regulations/SOR-2016-93/page-2.html (English) https://laws-lois.justice.gc.ca/fra/reglements/DORS-2016-93/page-2.html (French)

International Seed Morphology Association (ISMA). 2020. Method for Seed Size Measurement. Version 1.0. ISMA Publication Guide.

Lehtonen, P. and Schall, R. A. 2000. Inula britannica L. (British elecampane) Weed Risk Assessment. USDA, APHIS, PPQ. 15 pp., http://www.aphis.usda.gov/plant_health/plant_pest_info/weeds/ Accessed October 15, 2020.



Jennifer Neudorf, Angela Salzl, Ruojing Wang, Karen Castro, Katrina Entwistle

Canadian Food Inspection Agency