Fact Sheets


Panicum spp. L.

Family :

Famille :


Synonym(s) :

Synonyme(s) :

Common Name(s) :

Nom(s) commun(s) :

Panic grass
(English) (GC 2016)

Panic (French) (GC 2016)

  • Blue panic grass (Panicum antidotale) florets

  • Blue panic grass (Panicum antidotale) florets

  • Panicum antidotale floret

  • Panicum antidotale floret

  • Blue panic grass (Panicum antidotale) floret

  • Witch grass (Panicum capillare) florets 

  • Witch grass (Panicum capillare) florets and spikelet

  • Witch grass (Panicum capillare) floret, lemma view

  • Witch grass (Panicum capillare) floret, palea view

  • Fall panic grass (Panicum dichotomiflorum) spikelet (L) and floret (R)

  • Fall panic grass (Panicum dichotomiflorum) spikelets and floret 

  • Panicum virgatum (switchgrass) florets

  • Panicum virgatum (switchgrass) florets and spikelet

  • Panicum virgatum (switchgrass) floret

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Regulation :

Remarques Réglementation:

  • CFIA Weed Seeds Order - Class 4: Secondary Noxious Weed Seeds
  • CFIA Weed Seeds Order - Class 5: Noxious Weed Seeds

Regulation Notes:

Distribution :

Répartition :

Panicum is a large genus of 300 to 600 species originating from tropical and warm temperate parts of the world (Barkworth et al. 2003; Mabberley 2008). Panicum includes a number of weedy species as well as species cultivated as fodder, grain and ornamentals (Mabberley 2008). The genus includes 34 total species in North America and 6 species distributed across Canada with the exception of Newfoundland, Nunavut and Yukon Territory (Brouillet et al. 2010+; Barkworth et al. 2003).

Habitat and Crop Association :

Habitat et Cultures Associées :

Cultivated fields, old fields, pastures, prairies, shores, floodplains, marshes, swamps, ditches, shallow water, dunes, forest edges, forest clearings, open forests, orchards, vineyards, roadsides, railway lines and disturbed areas (Barkworth et al. 2003; Darbyshire 2003; DiTomaso and Healy 2007). The common weedy species Panicum capillare commonly infests Zea mays (corn), Glycine max (soybeans), Triticum aestivum subsp. aestivum (common wheat) and Sorghum bicolor (sorghum), and can also infest grasslands (Clements et al. 2004).

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 or perennial

Dispersal Unit Type :

Type d’unité de dispersion :

Spikelet or floret

General Information


Of the six species occurring in Canada, four are native and two are introduced (Brouillet et al. 2010+). Most species occur as weeds of agricultural habitats (Darbyshire 2003; Clements et al. 2004). Panicum capillare, a weedy native species, is the most commonly found in cultivated fields and gardens (Frankton and Mulligan 1993).

Panicum virgatum and Panicum miliaceum subsp. miliaceum are cultivated for seed and forage, and P. miliaceum subsp. ruderale is a weedy form that is common and competitive in corn fields in Canada (Royer and Dickinson 1999; Darbyshire 2003).




  • Spikelet


    • Spikelets of weedy species Panicum capillare length*: 1.9 – 4.0 mm
    • Spikelets of weedy species Panicum dichotomiflorum length*: 1.8 – 3.8 mm; width: 0.7 – 1.2 mm
    • Spikelets of crop species Panicum miliaceum subsp. miliaceum length*: 4.0 – 6.0 mm
    * from Barkworth et al. 2003


    • Spikelets are oval or teardrop-shaped, one end gradually narrows into a short or long point

    Surface Texture

    • Spikelets are smooth textured with several longitudinal nerves


    • Spikelets are dull straw-yellow, brown or reddish brown

    Other Features

    • Spikelets have a papery consistency and may be removed by processing
  • Floret


    • Florets of weedy species. Panicum capillare length*: 1.3 – 1.7 mm; width 0.7 – 0.8 mm
    • Florets of weedy species Panicum dichotomiflorum length +: 1.4 – 2.5 mm; width: 0.7 – 1.1 mm
    • Florets of crop species Panicum miliaceum subsp. miliaceum length +: 3.0 – 3.8 mm; width: 2.0 – 2.5 mm
    *Note: minimum and maximum of 10 florets in a normal range of this species using image measurement (ISMA 2020)
    + from Barkworth et al. 2003


    • Florets of Panicum species are oval or egg-shaped, plano-convex in edge view

    Surface Texture

    • Florets of Panicum species have a smooth surface


    • Florets of weedy Panicum species are shiny or glossy brown or greenish-brown with straw yellow ends and longitudinal stripes
    • Florets of crop Panicum species are glossy straw yellow or orange coloured

    Other Features

    Callus and Rachilla

    • Callus at wide end of floret is kidney shaped and dull straw yellow, brown or black

    Other Features

    • Palea teeth not visible
  • Caryopsis


    • Caryopsis size similar to floret size


    • Caryopsis is oval shaped, compressed in edge view

    Surface Texture

    • The caryopsis surface is smooth


    • Caryopsis is translucent straw yellow coloured

    Other Features

    • Caryopsis has a dark brown round or oval hilum near the end of the caryopsis, opposite the embryo side
  • Embryo


    • Embryo is a rudimentary size compared to the caryopsis


    • Oval shaped, lateral position at one end of the caryopsis on one side


    • Endosperm is hard and a translucent whitish colour

Identification Tips


Genera from the same tribe as Panicum species, Paniceae, have features that distinguish them from other grass tribes such as:
• Shed as a spikelet
• Spikelets have papery, unequal glumes, a papery sterile lemma and a hard, or leathery fertile floret
• Florets lack a rachilla or pedicels
• Inconspicuous palea teeth
• Florets tend to be short oval rather than elongate

Within the Paniceae tribe, Panicum species can be distinguished by:

• Smooth, floret surface
• Glossy colour
• Kidney shaped callus
• Several light brown longitudinal stripes on the lemma of weedy Panicum species
• Florets have a hard, shell-like consistency, not leathery or papery as in other Poaceae genera


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.

Digitaria spp. L. (crabgrasses)

Digitaria species are compressed in edge view, spikelets are hairy, glumes are shorter than the floret, floret surface is pitted and does not have a striped colour pattern.

In comparison, Panicum species spikelets are generally inflated in edge view, glumes are smooth and cover the floret, florets are smooth and a glossy colour with a striped colour pattern.

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Barkworth, M. E., Capels, K. M., Long, S., Anderton, L. K. and Piep, M. B., (eds.) 2003. Volume 25. Magnoliophyta: Commelinidae (in part): Poaceae, part 2. Oxford University Press, New York, New York.

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 April 1, 2021.

Clements, D. R., DiTommaso, A., Darbyshire, S. J., Cavers, P. B. and Sartonov, A. D. 2004. The biology of Canadian weeds. 127. Panicum capillare L. Canadian Journal of Plant Science 84: 327–341.

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

DiTomaso, J. M. and Healy, E. A. 2007. Weeds of California and Other Western States. Vol. 1. 834 pp. University of California, CA.

Frankton, C. and Mulligan, G. A. 1993. Weeds of Canada. Agriculture Canada, Publication 948.

Global Biodiversity Information Facility (GBIF) Secretariat. 2022. https://doi.org/10.15468/39omei Accessed via https://www.gbif.org/species/2705064 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.

Mabberley, D. J. 2008. Mabberley’s plant-book: A portable dictionary of plants, their classification and uses (3rd eds). Cambridge University Press, Cambridge, UK. 1021 pp.

Royer, F. and Dickinson, R. 1999. Weeds of Canada and the Northern United States. The University of Alberta Press/Lone Pine Publishing, Edmonton, Alberta.

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