Fact Sheets


Carduus nutans L.

Family :

Famille :


Synonym(s) :

Synonyme(s) :

Common Name(s) :

Nom(s) commun(s) :

Nodding thistle
(English) (GC 2016)

Chardon penché (French) (GC 2016)

Musk thistle (English) (AOSA 2019)

  • Nodding thistle (Carduus nutans) achenes

  • Nodding thistle (Carduus nutans) achenes

  • Nodding thistle (Carduus nutans) achene

  • Nodding thistle (Carduus nutans) achene

  • Nodding thistle (Carduus nutans) top of achene

  • Nodding thistle (Carduus nutans) bottom of achene

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Regulation :

Remarques Réglementation:

  • CFIA Weed Seeds Order - Class 2: Primary Noxious Weed Seeds

Regulation Notes:

Distribution :

Répartition :

Native to northern Africa, temperate Asia, and Europe (USDA-ARS 2020). Introduced in North America, Chile, South Africa, Australia, New Zealand and beyond its native range in Europe (USDA-ARS 2020). Occurs across Canada with the exception of Northwest Territories, Nunavut, Prince Edward Island, Yukon (Brouillet et al. 2010+; Desrochers et al. 1988).

Habitat and Crop Association :

Habitat et Cultures Associées :

Old fields, pastures, rangelands, roadsides and disturbed areas (Desrochers et al. 1988; Darbyshire 2003).

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


Carduus nutans is believed to have arrived in eastern North America in ship’s ballast, and introduced to Saskatchewan through Brassica spp. (rapeseed) and dispersed along railway lines (Desrochers et al. 1988).

This species produces large numbers of seeds (11,000) per plant and may form dense stands in disturbed areas such as gravel pits, roadsides and overgrazed pasture (Desrochers et al. 1988).


Carduus nutans infestation (Norman E. Rees, USDA Agricultural Research Service – Retired, Bugwood.org)



  • Achene


    • Achene length*: 2.3 – 3.7 mm; width: 0.9 – 1.5 mm
    *Note: minimum and maximum of 20 achenes in a normal range of this species using image measurement (ISMA 2020)


    • Achene oblong or elongated oval shape, straight or slightly curved in the long side view
    • One end narrow and the other wider and truncate
    • Generally compressed laterally

    Surface Texture

    • Mature achene surface smooth, looks varnished
    • Immature achene surface may be roughened by transverse wavy ridges


    • Achene is glossy light yellow, dark yellowish brown, or orange-brown; the truncate end can be yellow or yellowish brown
    • Brown coloured longitudinal stripes and transverse waves are under the achene’s varnish-like surface coating
    • Immature achenes may be light yellow coloured with yellowish ends

    Other Features


    • A thin, white, hair-like pappus up to 2.0 cm (CABI 2019) may be attached to the achene, but is generally removed during processing

    Achene end with pappus

    • The style remnant at the truncate end of achene is usually short and thick
  • Seed


    • Seed is similar to achene size


    • Seed is oblong

    Surface Texture

    • Seed is smooth


    • Seed is yellow

    Other Features

    • Seed coat thin, yellow, adhering to the fruit wall
  • Embryo


    • Embryo fills the seed


    • Embryo is spatulate, axial position


    • Endosperm is absent, nutritive tissue stored in the cotyledons

    Other Features

    • Cotyledons are soft-textured

Identification Tips


The achenes of Carduus nutans are distinguished by the yellow-brown colour, smooth, glossy surface compared to similar Carduus species.

Additional Botany Information



  • Flowers are tubular and bright pink or purple, rarely white (Desrochers et al. 1988)


Vegetative Features

  • The flower heads of C. nutans are generally large (width: 20.0 – 70.0 mm; FNA 1993+), and the hairy involucral bracts curl away from the flower head (FNA 1993+)
  • Mature flower heads droop towards the stem (Desrochers et al. 1988)

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.

Carduus acanthoides L. (spiny plumeless thistle)

C. acanthoides achenes are generally wider (width*: 1.2 – 1.4 mm) than C. nutans achenes. C. acanthoides achenes generally have grey or pinkish ends, not yellowish or brownish as C. nutans, and the surface has wavy ridges while the surface of C. nutans is smooth and covered with a varnish-like coating. Immature C. nutans achenes may also have a rough surface, but one or both ends will be yellowish.

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

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Association of Official Seed Analysts (AOSA). 2019. AOSA Rules For Testing Seeds. Volume 3: Uniform Classification of Weed and Crop Seeds. AOSA, Washington, DC.

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 5, 2019.

Darbyshire, S. J. 2003. Inventory of Canadian Agricultural Weeds. Agriculture and Agri-Food Canada, Research Branch. Ottawa, ON.

Desrochers, A. M., Bain, J. F. and Warwick, S. I. 1988. The Biology of Canadian weeds. 89. Carduus nutans L. and Carduus acanthoides L. Canadian Journal of Plant Science 68: 1053-1068.

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

Global Biodiversity Information Facility (GBIF) Secretariat. 2022. https://doi.org/10.15468/39omei Accessed via https://www.gbif.org/species/8185959 Accessed December 29, 2022

International Seed Morphology Association (ISMA). 2020. Method for Seed Size Measurement. Version 1.0. ISMA Publication Guide. https://www.idseed.org/authors/details/method_for_seed_size_measurement.html

U.S. Department of Agriculture-Agricultural Research Services (USDA-ARS). 2022. Germplasm Resources Information Network (GRIN), https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysimple.aspx Accessed October 15, 2020.



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

Canadian Food Inspection Agency