Fact Sheets


Tripleurospermum inodorum (L.) Sch. Bip.

Family :

Famille :


Synonym(s) :

Synonyme(s) :

Matricaria inodora L.
Matricaria perforata Mérat
Tripleurospermum maritimum (L.) W. D. J. Koch subsp. inodorum (L.) Appleq.


Common Name(s) :

Nom(s) commun(s) :

Scentless chamomile
(English) (GC 2016)

Matricaire camomille (French) (GC 2016)

Scentless mayweed (English) (FNA 1993+)

False mayweed (English) (FNA 1993+)

False chamomile (English) (FNA 1993+)

  • Scentless chamomile (Tripleurospermum inodorum) achenes

  • Scentless chamomile (Tripleurospermum inodorum) achenes

  • Scentless chamomile (Tripleurospermum inodorum) achene, side without ribs

  • Scentless chamomile (Tripleurospermum inodorum) achene, side with ribs

  • Scentless chamomile (Tripleurospermum inodorum) achene, side view

  • Scentless chamomile (Tripleurospermum inodorum) achene, top-down view

  • Scentless chamomile (Tripleurospermum inodorum) achene, top-down view

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Regulation :

Remarques Réglementation:

  • CFIA Weed Seeds Order - Class 3: Secondary Noxious Weed Seeds
  • CFIA Weed Seeds Order - Class 5: Noxious Weed Seeds
  • Quarantine lists of countries e.g. India *may be updated without notice
  • Quarantine lists of countries e.g. Mexico *may be updated without notice

Regulation Notes:

Distribution :

Répartition :

Native to Europe and temperate Asia and introduced in North and South America, the Azores, Poland, Russian Federation (Primorye), and New Zealand (USDA-ARS 2020). In the United States, widespread in the north but absent from much of the south (USDA-NRCS 2020). Occurs in throughout Canada except in Nunavut (Brouillet et al. 2010+).

Habitat and Crop Association :

Habitat et Cultures Associées :

Cultivated fields, old fields, pastures, hay fields, farm yards, fence lines, gardens, lawns, ditches, roadsides, railway lines and disturbed areas (Woo et al. 1991; 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:

Annual, biennial or perennial

Dispersal Unit Type :

Type d’unité de dispersion :


General Information


Tripleurospermum inodorum was recorded in Canada in the late 1800s and is believed to have arrived in ship ballast, as a garden plant, and as a seed contaminant from Europe (Woo et al. 1991).

Dense stands of T. inodorum have approximately 3200 flower heads and may produce up to 1.8 million achenes per square meter (Woo et al. 1991). These achenes can remain viable in the soil for up to about 10 years (Woo et al. 1991).


Tripleurospermum inodorum plant (K. George Beck and James Sebastian, Colorado State University, Bugwood.org)



  • Achene


    • Achene length*: 1.7 – 3.1 mm; width: 0.7 – 1.6 mm
    *Note: minimum and maximum of 20 achenes in a normal range of this species using image measurement (ISMA 2020)


    • Rectangular to wedge-shaped achene

    Surface Texture

    • Three ribs are clustered on one side of the achene with oil ducts between the ribs
    • Other side of the achene has a large, oval shaped oil duct with 2 smooth, round resin glands at one end
    • Surface is ridged reticulate and transversely wrinkled between ribs


    • Ribs are shining light to medium brown, oil ducts dark brown, resin glands are reddish

    Other Features


    • Pappus is a short, thin rim of scales around the style remnant (Woo et al. 1991)

    Achene end with pappus

    • Resin glands usually round and reddish
    • A small style peg is in the center at the end of the achene bearing the pappus
    • The resin glands can be seen through this end when looking down at the remnant style of the achene

    Achene end without pappus

    • A small ring of tissue exists at the end of the achene that was attached to the flower head
  • Seed


    • Seed is similar in length as achene but is a thinner width


    • Seed is compressed, oval shape with a gradually point end

    Surface Texture

    • Smooth seed texture


    • Seed is a shiny orange colour

    Other Features

    Seed coat is translucent

  • Embryo


    • Embryo fills the seed


    • Embryo is spatulate shaped, axial position


    • Endosperm absent, nutritive tissue stored in the cotyledons

Identification Tips


The feature combination of ribs on one side of the achene with oil ducts on the other side are found in a number of genera in the family including: Tripleurospermum species, Matricaria species and Chamomilla species. Tripleurospermum inodorum achenes can be distinguished by the thick ribs, dark brown oil ducts and the presence of round resin glands on the achenes.

Additional Botany Information



  • Flower heads are hemispherical or cone-shaped, 20.0 – 45.0 mm diameter, have yellow disk flowers and white ray flowers (Woo et al. 1991)

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.

Tripleurospermum maritimum (L.) W.D.J.Koch (seaside chamomile)

T. maritimum achenes are generally larger (length*: 2.8 – 4.5 mm; width: 1.2 – 1.8 mm) than T. inodorum achenes, a darker brown colour, with a narrow space between the ribs. The resin glands cannot be seen from the style remnant end of the achene, and are generally brown and oval shaped rather than the round, reddish coloured ones in T. inodorum.

*Note: minimum and maximum of 20 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 November 24, 2020.

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

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/3104179 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.

Woo, S. L., Thomas, A. G., Peschken, D. P., Bowes, G. G., Douglas, D. W., Harms, V. L. and McClay, A. S. 1991. The biology of Canadian weeds. 99. Matricaria perforata Mèrat (Asteraceae). Canadian Journal of Plant Science 71: 1101-1119.

U.S. Department of Agriculture-Agricultural Research Services (USDA-ARS). 2020. Germplasm Resources Information Network (GRIN), https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysimple.aspx Accessed November 24, 2020.

U.S. Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS). 2020. The PLANTS Database. National Plant Data Team, Greensboro, NC USA. http://plants.usda.gov Accessed November 24, 2020.



Jennifer Neudorf, Angela Salzl, Ruojing Wang, Karen Castro, Katrina Entwistle
Canadian Food Inspection Agency