Weed Seed: Avena fatua (Wild oat)



Common Name

Wild oat


Secondary Noxious, Class 3 in the Canadian Weed Seeds Order, 2016 under the Seeds Act.


Canadian: Occurs across Canada except in NU; ephemeral in YT (Brouillet et al. 2016Footnote 1).

Worldwide: Native to Europe, northern Africa and central Asia (USDA-ARS 2016Footnote 2); associated with the cultivation of oats and other cereals since the Iron Age (CABI 2016Footnote 3). Introduced throughout temperate regions and present on all continents except Antarctica (CABI 2016Footnote 3; USDA-ARS 2016Footnote 2). Occurs throughout the United States, except in a few southeastern states (Kartesz 2011Footnote 4, USDA-NRCS 2016Footnote 5).

Duration of life cycle


Seed or fruit type


Identification features


  • Floret length: 10.0 - 15.0 mm
  • Floret width: 2.5 - 4.0 mm
  • Caryopsis length: 6.0 - 8.0 mm
  • Caryopsis width: 2.0 - 3.0 mm


  • Floret elongate; tapered at the top and narrowed at the base with a flared callus

Surface Texture

  • Floret has a rough surface
  • Long, stiff hairs around the base of floret


  • Floret tends to be a reddish colour with a straw yellow tip, but can be straw yellow to brown

Other Features

  • Callus at the base of the floret is prominent and spoon- shaped
  • Caryopsis is covered in hairs, the scutellum is absent and often has an indentation where the awn arose from the lemma
  • A strongly bent and twisted awn is attached to the upper 1/2 of the lemma; up to 40.0 mm long

Habitat and Crop Association

Cultivated fields, fallow fields, pastures, gardens, roadsides and disturbed areas (Sharma and Vanden Born 1978Footnote 6, Darbyshire 2003Footnote 7). A serious weed of cereals, oilseeds and legume crops, mainly associated with fertile soils and spring cereals but can be found on nearly all soil types in a wide range of cropping systems (Sharma and Vanden Born 1978Footnote 6, CABI 2016Footnote 3).

General Information

Wild oat has relatively large seeds and its dispersal is associated with the cultivation of cereal crops around the world (CABI 2016Footnote 3). In North America, it was introduced by early European settlers as a contaminant in seeds and animal feed, and the earliest record in Canada indicates it was present in oats cultivated in Newfoundland in 1622 (Sharma and Vanden Born 1978Footnote 6). Since then it has spread across the continent in cereals and other crops.

A single wild oat plant typically produces 100-150 seeds, with reports of up to 500 seeds per plant depending on growing conditions (Sharma and Vanden Born 1978Footnote 6); seeds may remain viable for up to 14 years (CABI 2016Footnote 3).

Similar species

Tame oat (Avena sativa)

  • Tame oat florets are a similar to those of wild oat in length, elongated shape, lighter colour and a pointed rachilla.
  • Tame oat florets tend to be wider (width: 2.5 - 4.5 mm), a uniform straw yellow (although red-brown and grey varieties occur), with a smooth to slightly pebbled surface.
  • The callus of tame oat tends to be peg-like and fractured. There may be a rudimentary awn that does not create an indentation on the caryopsis.


Wild oat (Avena fatua); florets and caryopsis
Wild oat (Avena fatua) floret, palea view
Wild oat (Avena fatua) floret, lemma view
Wild oat (Avena fatua) floret, side view
Wild oat (Avena fatua) caryopses, embryo view
Wild oat (Avena fatua) florets, lemma view (L) and palea view (R)
Wild oat (Avena fatua) floret, cross-section
Wild oat (Avena fatua) caryopses

Similar species

Similar species: Tame oat (Avena sativa) florets
Similar species: Tame oat (Avena sativa) floret, palea view
Similar species: Tame oat (Avena sativa) floret, lemma view
Similar species: Tame oat (Avena sativa) caryopses, embryo view and centre - hilum view
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