Fact Sheets


Galium verrucosum Huds.

Family :

Famille :


Synonym(s) :

Synonyme(s) :

Galium saccharatum All. (POWO 2022)

Aparine verrucosa (Huds.) Moench                            (POWO 2022; Tropicos 2022)

Galium valantia Weber                                                    (Danin and Fragman 2016+; POWO 2022)

Common Name(s) :

Nom(s) commun(s) :

Warty bedstraw
(English) (GC 2016; ITIS 2022)

Gaillet à verrues (French) (GC 2016)

  • Warty bedstraw (Galium verrucosum) fruits

  • Warty bedstraw (Galium verrucosum) schizocarp and fruits

  • Warty bedstraw (Galium verrucosum) fruit, inner side

  • Warty bedstraw (Galium verrucosum) fruit, outer side

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Regulation :

Remarques Réglementation:

  • CFIA Weed Seeds Order - Class 3: Secondary Noxious Weed Seeds

Regulation Notes:

Distribution :

Répartition :

Native to southern Europe and the Mediterranean (Tutin et al. 1976; Hanf 1983). Naturalized in central Europe (Tutin et al. 1976). In the United States it has been introduced in Michigan (USDA-NRCS 2022). The species is not present in Canada (Brouillet et al. 2010+).

Habitat and Crop Association :

Habitat et Cultures Associées :

This species grows in cultivated fields, in scrub and degraded grassland (Hanf 1983).

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 :

Schizocarp, divided into 2 mericarps

General Information


Galium verrucosum seed has been introduced into Great Britain as a contaminant in imported bird food (Hanson and Mason 1985). Historically, it was recorded in Zea mays L. subsp. mays (corn) fields in Great Britain (Lindley 1835).




  • Mericarp


    • Mericarp length*: 2.7 – 4.6 mm; width: 2.4 – 3.7 mm
    *Note: minimum and maximum of 10 mericarps in a normal range of this species using image measurement (ISMA 2020)


    • Mericarp is round, compressed at the attachment scar and looks D-shaped in 3D

    Surface Texture

    • Mericarp surface is covered with warty tubercles
    • Tubercles have pointed tips and an irregular base


    • Mericarp is dull, straw yellow or brown coloured
    • Immature fruit is green (Danin and Fragman 2016+)

    Other Features


    • Hilum is located under the attachment scar on one side of the fruit

    Other than hilum

    • The fruit layer has a spongy consistency and can be scraped away
    • Two one-seeded mericarps are joined at the hilum side and form the schizocarp
  • Seed


    • Seed is smaller than the mericarp


    • Seed is globose

    Surface Texture

    • Seed surface is wrinkled


    • Seed is dark reddish brown

    Other Features

    Hilum and Hilum area

    • Hilum is in a transverse oval shaped hole underneath the attachment scar on the fruit

    Other Features

    • Short, linear white streaks from raphides (crystals) on the seed surface
  • Embryo


    • Embryo size is rudimentary


    • Embryo is spatulate shaped (Martin 1946)


    • Endosperm is hard and colourless

    Other Features

    • Embryo is in a peripheral position

Identification Tips


Galium verrucosum fruits are medium-sized with a distinctive warty tuberculate surface that covers the hilum. The pointed tubercles of the fruit surface make it an identifiable species without closer study.

Additional Botany Information



  • Flowers are white (Danin and Fragman 2016+)

Vegetative Features

  • Leaves with smooth margins are arranged in whorls of three or more (Danin and Fragman 2016+)

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.

Galium aparine L. (cleavers)

G. aparine mericarps are generally smaller (diameter*: 1.6 – 3.2 mm) have translucent white tubercles associated with bristles and a large hole at the hilum compared to yellowish tubercles without bristles and tissue covering the hilum of G. verrucosum mericarps.

*Note: minimum and maximum of 20 mericarps 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 March 28, 2022. 

Danin, A. & O. Fragman- Sapir. 2016+ Flora of Israel Online.  https://flora.org.il/en/plants/ Accessed March 09, 2022. 

Global Biodiversity Information Facility (GBIF) Secretariat. 2022. https://doi.org/10.15468/39omei Accessed via https://www.gbif.org/species/2914754 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) 

Hanf, M. 1983. The Arable Weeds of Europe. BASF Aktiengessellschaft, Ludwigshafen, Germany. 

Hanson, C. G. and Mason, J. L. 1985. Bird seed aliens in Britain. Walsonia 15: 237-252. 

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

Lindley, J. 1835. A Synopsis of the British Flora: Arranged According to the Natural Orders, 2nd Edition Longman, Rees, Orme, Brown, Green, and Longman, London, UK. 

Martin, A.C. 1946. The comparative internal morphology of seeds. The American Midland Naturalist 36: 513-660. 

Plants of the World Online (POWO). 2022. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://www.plantsoftheworldonline.org/ Accessed March 09, 2022. 

Tropicos. 2022. Missouri Botanical Garden. https://tropicos.org Accessed March 09, 2022. 

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. and Webb, D. A. (eds.) 1976. Flora Europaea. Volume 4: Plantaginaceae to Compositae (and Rubiaceae). Cambridge University Press, Cambridge, UK. 

U.S. Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS). 2022. The PLANTS Database. National Plant Data Team, Greensboro, NC USA. http://plants.usda.gov Accessed December 29, 2022.



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

Canadian Food Inspection Agency