Fact Sheets


Galeopsis tetrahit L.

Family :

Famille :


Synonym(s) :

Synonyme(s) :

Common Name(s) :

Nom(s) commun(s) :


  • Hemp-nettle (Galeopsis tetrahit) nutlets

  • Hemp-nettle (Galeopsis tetrahit) nutlets

  • Hemp-nettle (Galeopsis tetrahit) nutlet

  • Hemp-nettle (Galeopsis tetrahit) nutlet

  • Hemp-nettle (Galeopsis tetrahit) nutlets; immature (R)

  • Hemp-nettle (Galeopsis tetrahit) nutlets; immature (R)

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Regulation :

Remarques Réglementation:

  • Quarantine lists of countries e.g. Mexico *may be updated without notice

Regulation Notes:

On quarantine lists of countries e.g. Mexico*.

*Quarantine lists of countries may be updated without notice.

Distribution :

Répartition :

This species is native to Europe and temperate Asia and introduced elsewhere, including North America (O’Donovan and Sharma 1987; GBIF 2017; USDA-ARS 2017). Widespread in the northern United States (USDA-NRCS 2017).

Habitat and Crop Association :

Habitat et Cultures Associées :

Hemp-nettle grows in cultivated fields, pastures, swamps, thickets, forests, ditches, roadsides and disturbed areas (Darbyshire 2003). It favours well-watered nutrient-rich soils; low soil moisture can be a limiting factor in its distribution and spread (O’Donovan and Sharma 1987).

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


Hemp-nettle is an agricultural weed known to reduce yields of several crops and to be a reservoir for several plant pathogens (e.g., Phoma exigua) and nematodes (e.g., Ditylenchus dipsaci; Heterodera spp.). Nutlets are a serious contaminant of small grains (O’Donovan and Sharma 1987).


Galeopsis tetrahit infestation (Michael Shephard, USDA Forest Service, Bugwood.org)



  • Nutlet


    • Nutlet length: 2.8 – 3.2 mm (average: 3.0 mm); width: 2.2 – 2.7 mm (average: 2.5 mm)


    • Nutlet is egg-shaped in outline, compressed
    • The point of attachment is oval-shaped and concave, offset to one side of the narrow end with a short ridge leading from it
    • Immature nutlets are a teardrop shape, abruptly narrowed at the point of attachment

    Surface Texture

    • Nutlet surface is sparsely or densely covered in patches of bubbled texture
    • The point of attachment is roughened


    • Nutlet is slightly shiny, light or medium brown with occasional black spots; the raised, bubbled patches are light-coloured
    • Immature nutlets are a uniform light brown

    Other Features

    • Immature nutlets are mostly smooth, with scattered patches of a bubbled texture

Identification Tips


Additional Botany Information


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.

Galeopsis pubescens (hairy hemp-nettle) and Galeopsis speciosa (large-flowered hemp-nettle)

Both hairy and large-flowered hemp-nettle nutlets are similarly shaped, are brown-coloured with black spots, with light-coloured patches of bubbled surface texture and a concave attachment point offset at the narrow end.

Hairy hemp-nettle nutlets are generally smaller (average length: 2.5 mm; average width: 2.0 mm), and have a dark brown background colour.

Large-flowered hemp-nettle nutlets are generally narrower (average width: 2.1 mm) and have a dark brown background colour.

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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 2017, GBIF Home Page. https://www.gbif.org Accessed April 25, 2017.

Global Biodiversity Information Facility (GBIF) Secretariat. 2022. https://doi.org/10.15468/39omei Accessed via https://www.gbif.org/species/2703746 Accessed December 29, 2022.

O’Donovan, J. T. and Sharma, M. P. 1987. The biology of Canadian weeds. 78. Galeopsis tetahit L. Canadian Journal of Plant Science 67: 787-796.

U.S. Department of Agriculture-Agricultural Research Services (USDA-ARS). 2017. Germplasm Resources Information Network (GRIN), https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch Accessed April 25, 2017.

U.S. Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS). 2017. The PLANTS Database. National Plant Data Team, Greensboro, NC USA. https://plants.usda.gov/home Accessed April 25, 2017.



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

Canadian Food Inspection Agency