Weed Seed: Bromus japonicus (Japanese brome)

Family

Poaceae

Common Name

Japanese brome

Regulation

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

Distribution

Canadian: Occurs in AB, BC, MB, NB, NS, ON, QC, SK, YT (Brouillet et al. 2016Footnote 1).

Worldwide: Native to northern Africa and temperate Eurasia from France eastward to China, Japan and Korea (USDA-ARS 2016Footnote 2). Introduced in parts of Europe, Australia, New Zealand, South Africa and North and South America (Holm et al. 1991Footnote 3, USDA-ARS 2016Footnote 2). Occurs throughout most of the United States (Barkworth et al. 2007Footnote 4).

Duration of life cycle

Annual

Seed or fruit type

Floret

Identification features

Size

  • Floret length: 7.0 - 9.0 mm
  • Floret width: 1.0 - 2.0 mm
  • Awn length: 8.0 - 13.0 mm

Shape

  • Long oval-shaped floret with a flared top, and in-rolled and extended lemma sides

Surface Texture

  • Lemma is papery with hyaline margins, scabrous to ciliate on upper half and margins

Colour

  • Floret is straw yellow

Other Features

  • Palea teeth longer than 1.0 mm.
  • Awn bends away from the lemma.
  • The caryopsis is pubescent on the margins.

Habitat and Crop Association

Cultivated fields, old fields, rangelands, pastures, hay fields, gardens, roadsides, industrial sites and disturbed areas (Darbyshire 2003Footnote 5, Barkworth et al. 2007Footnote 4). A weed of winter wheat, grass and alfalfa seed fields, pastures and ranges, and many other places (Finnerty and Klingman 1962Footnote 6). Prefers somewhat moister habitats than B. tectorum (Kirkland and Brenzil 2007Footnote 7).

General Information

Japanese brome can invade pastures and rangelands where it competes with native species, but can be used as an early-season forage (Howard 1994Footnote 8). It has been observed to increase in natural areas under a fire-suppression management regime (Howard 1994Footnote 8).

In Canada, annual bromes are often an indicator of poor range condition, and readily infest areas where native vegetation has been disturbed by overgrazing, fire, and cultivation (Kirkland and Brenzil 2007Footnote 7). Japanese brome occurs as a contaminant in seed and grain (Canadian Grain Commission (CGC) data).

Similar species

Soft chess (Bromus hordeaceus)

  • Soft chess has a similar size, oval shape, straw colour and extended lemma sides.
  • The caryopsis is not pubescent on the margins. The lemmas of soft chess are often pilose, but may be glabrous. The awn is shorter, up to 4.0 mm.

Field brome (Bromus arvensis)

  • Field brome has a similar size, oval shape, straw colour and extended lemma sides.
  • Field brome's awn is up to 3.0 mm shorter than Japanese brome and does not bend backwards from the lemma. Field brome usually has glabrous lemmas, and they tend to not extend as much as Japanese brome lemmas.

Photos

Figure 1 - Japanese brome (Bromus japonicus) florets
Japanese brome (Bromus japonicus) florets
Figure 2 - Japanese brome (Bromus japonicus) florets
Japanese brome (Bromus japonicus) floret
Figure 2 - Japanese brome (Bromus japonicus) florets
Japanese brome (Bromus japonicus) florets
Figure 4 - Japanese brome (Bromus japonicus) palea (close-up)
Japanese brome (Bromus japonicus) palea (close-up)

Similar species

Figure 5 - Similar species: Soft chess (Bromus hordeaceus) florets
Similar species: Soft chess (Bromus hordeaceus) florets
Figure 6 - Similar species: Soft chess (Bromus hordeaceus) floret, palea teeth
Similar species: Soft chess (Bromus hordeaceus) floret, palea teeth
Figure 7 - Similar species: Soft chess (Bromus arvensis) florets
Similar species: Field brome (Bromus arvensis) florets
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