Fact Sheets


Digitaria spp. Haller

Family :

Famille :


Synonym(s) :

Synonyme(s) :

Common Name(s) :

Nom(s) commun(s) :

(English) (GC 2016)

Digitaire (French) (GC 2016)

  • Smooth crabgrass (Digitaria ischaemum) spikelets

  • Smooth crabgrass (Digitaria ischaemum) spikelet

  • Smooth crabgrass (Digitaria ischaemum) spikelet

  • Large crabgrass (Digitaria sanguinalis) spikelets

  • Large crabgrass (Digitaria sanguinalis) spikelets

  • Large crabgrass (Digitaria sanguinalis) spikelet, outer side

  • Large crabgrass (Digitaria sanguinalis) spikelet, inner side

  • Large crabgrass (Digitaria sanguinalis) spikelets, florets and caryopses

  • Southern crabgrass (Digitaria ciliaris) spikelets

  • Southern crabgrass (Digitaria ciliaris) spikelet

  • Southern crabgrass (Digitaria ciliaris) spikelet

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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 :

The genus contains about 250 species originating from tropical and warm temperate parts of the world (Mabberley 2008). It includes cultivated and weedy species, some widely introduced around the world (USDA-ARS 2021). The genus includes 29 species that occur in North America (Barkworth et al. 2003), species distributed across Canada with the exception of Newfoundland and the territories (Brouillet et al. 2010+).

Habitat and Crop Association :

Habitat et Cultures Associées :

Cultivated fields, pastures, gardens, lawns, orchards, vineyards, shores, roadsides, railway lines and disturbed areas (Darbyshire 2003; CABI 2021). Weedy species infest a variety of crop fields worldwide and are problematic in lawns (CABI 2021).

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:

Most species annual; some perennial

Dispersal Unit Type :

Type d’unité de dispersion :


General Information


Of the 29 Digitaria species distributed in North America, 18 are native to the area and the rest are introduced weeds (Barkworth et al. 2003). The species occurring in Canada are: the introduced species Digitaria sanguinalis (large crabgrass) and D. ischaemum (smooth crabgrass ) and the native species D. cognata (fall crabgrass ) (Darbyshire 2003; Brouillet et al. 2010+).

Digitaria species are known mostly as problem weeds in sandy and loam soils (Darbyshire 2003; CABI 2021). Large Digitaria species plants can generally produce 150,000 seeds in a growing season and mature plants spread over large areas by tillering soon after establishment (CABI 2021).


Digitaria spp. seedling (Joseph M. DiTomaso, University of California – Davis, Bugwood.org)



  • Spikelet


    • Size of spikelets of Digitaria species are variable, ranging from 1.2 – 8.2 mm long (Barkworth et al. 2003)
    • The most commonly encountered weedy species in North America are D. sanguinalis and D. ischaemum (Barkworth et al. 2003)
    • D. ischaemum spikelet length: 1.7 – 2.3 mm (Barkworth et al. 2003)
    • D. sanguinalis spikelet length*: 2.1 – 2.9 mm; width: 0.8 – 1.0 mm
    *Note: minimum and maximum of 10 spikelets in a normal range of this species using image measurement (ISMA 2020)


    • Digitaria species spikelets are short or long oval-shaped, compressed in edge view

    Surface Texture

    • Digitaria species spikelets are generally hairy with several longitudinal nerves


    • Spikelets are dull straw-yellow or light green

    Other Features

    • The glumes are generally triangular shaped and can partially or completely cover the floret depending on the species
    • The sterile lemma completely covers the palea side of the fertile floret in all Digitaria species
  • Floret


    • Floret size same as the spikelet size


    • Florets oval shaped, compressed in edge view

    Surface Texture

    • Florets appear to have smooth surfaces, but are pitted in longitudinal lines under high magnification


    • Florets are generally shiny brown or greenish-brown coloured, some species are black

    Other Features

    • Lemmas have distinctive thin, translucent margins that wrap around the palea, covering the edges
    • Palea teeth are not visible
  • Caryopsis


    • Caryopsis length similar to floret length


    • Caryopsis is oval shaped, compressed in edge view

    Surface Texture

    • Caryopsis has a smooth surface


    • Caryopsis is translucent shiny white or light brown 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


    • Embryo is oval shaped, in a lateral position, at an end of the caryopsis on one side


    • Endosperm is hard and translucent, almost colourless

    Other Features

    • Embryo is up to ½ the length of the caryopsis (Barkworth et al. 2003)

Identification Tips


Genera from the same tribe as Digitaria species, the Paniceae, have certain features that distinguish them from other tribes in the Poaceae:

  • Shed as a spikelet
  • Spikelets have papery, unequal glumes, a papery sterile floret and a hard, shell-like 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, Digitaria species have distinguishing features:

  • Triangular glume partially covering the lemma in some species
  • Florets with a pitted surface in longitudinal lines
  • Florets are black in some species
  • Callus not visible

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.

Panicum spp. L. (panic grasses)

Panicum species are generally inflated in side view, spikelets are not hairy, glumes cover the floret, florets are smooth, glossy brown or yellow coloured with a striped colour pattern. Digitaria species spikelets are generally compressed in side view, glumes are hairy and partially cover the floret, florets with pitting, and a shiny brown colour in comparison.

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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 March 23, 2021.

Centre for Agriculture and Bioscience International (CABI). 2021. Invasive Species Compendium, CAB International, Wallingford, UK. https://www.cabidigitallibrary.org/journal/cabicompendium Accessed March 23,2021.

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

Global Biodiversity Information Facility (GBIF) Secretariat. 2022. https://doi.org/10.15468/39omei Accessed via https://www.gbif.org/species/2704525 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.   https://www.idseed.org/authors/details/method_for_seed_size_measurement.html

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.

U.S. Department of Agriculture-Agricultural Research Services (USDA-ARS). 2021. Germplasm Resources Information Network (GRIN), https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysimple.aspx Accessed March 23, 2021.

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