Weed Seed: Setaria faberi (Giant foxtail)

Family

Poaceae

Common Name

Giant foxtail

Regulation

Primary Noxious, Class 2 in the Canadian Weed Seeds Order, 2016 under the Seeds Act.

Distribution

Canadian: Occurs in ON and QC (Brouillet et al. 2016Footnote 1).

Worldwide: Native to temperate eastern Asia and introduced in North America, central Europe, Russia and the Middle East (Nurse et al. 2009Footnote 2, USDA-ARS 2016Footnote 3). In the United States, it occurs mostly in the east and is expanding westward (Nurse et al. 2009Footnote 2).

Duration of life cycle

Annual

Seed or fruit type

Spikelet

Identification features

Size

  • Spikelet length: 2.5 - 3.5mm
  • Spikelet width: 1.5 - 2.0 mm

Shape

  • Spikelet ovate with a pointed tip; one side is flat (plano-convex)

Surface Texture

  • Lemma surface is transversely ridged, smooth at the tip
  • Palea is grid-patterned with 2 shiny crescents along the outer edges

Colour

  • Spikelet straw yellow to medium brown

Other Features

  • The papery second glume extends up to 3/4 of the length of the lemma

Habitat and Crop Association

Cultivated fields, old fields, gardens, roadsides, railway lines and disturbed areas (Darbyshire 2003Footnote 4). A weed of a variety of crops, but causes the greatest losses in corn and soybeans (Nurse et al. 2009Footnote 2, CABI 2016Footnote 5).

General Information

Giant foxtail may have been introduced into North America as a contaminant of imported millet. It may also contaminate bird seed and flower seed mixtures as well as other crop seeds. In Canada, the occurrence of giant foxtail coincided with the cultivation of field corn beginning in the 1960s (Nurse 2009Footnote 2).

Similar species

Yellow foxtail (Setaria pumila subsp. pumila)

  • Yellow foxtail is similar in size, yellow colour, lemma wrinkling and ovate shape as giant foxtail spikelets. The lemma ridges of yellow foxtail remain strong to the tip, the palea lacks the shiny outer edges of giant foxtail, and the second glume reaches halfway up the lemma.

Photos

Giant foxtail (Setaria faberi) spikelet and florets
Giant foxtail (Setaria faberi) spikelet
Giant foxtail (Setaria faberi) floret, lemma view
Giant foxtail (Setaria faberi) floret, side view
Giant foxtail (Setaria faberi) floret, palea view
Giant foxtail (Setaria faberi) spikelets

Similar species

Similar species: Yellow foxtail (Setaria pumila subsp. pumila) spikelet
Similar species: Yellow foxtail (Setaria pumila subsp. pumila) floret, palea view
Similar species: Yellow foxtail (Setaria pumila subsp. pumila) floret, lemma view
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