Weed Seed: Elymus repens (Quackgrass)

Family

Poaceae

Synonym

Couchgrass

Common Name

Quackgrass

Regulation

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

Distribution

Canadian: Occurs in every province and territory (Brouillet et al. 2016Footnote 1).

Worldwide: Exact native range obscure; however, likely native to northern Africa, Europe, temperate Asia, northern India and Pakistan. Introduced in other parts of Africa, North America, Argentina, Chile, Australia and New Zealand (USDA-ARS 2016Footnote 2). Occurs throughout the United States, except for some regions in the southeast (Kartesz 2011Footnote 3).

Duration of life cycle

Perennial

Seed or fruit type

Floret

Identification features

Size

  • Floret length: 5.0 - 10.0 mm
  • Floret width: 1.0 - 1.5 mm

Shape

  • Floret elongate, concave on palea side, lemma may have a short awn

Surface Texture

  • Floret surface is smooth with a shiny bump at the base of the lemma

Colour

  • Floret straw-colour

Other Features

  • The rachilla has parallel sides, with a U-shaped sinus at its base. The palea teeth are short and thick
  • No hairs on the callus at the base of the lemma

Habitat and Crop Association

Cultivated fields, pastures, old fields, cattle yards, river flats, roadsides, railway lines, and other disturbed areas (Darbyshire 2003Footnote 4, CABI 2016Footnote 5). A weed of all cultivated crops (Royer and Dickinson 1999Footnote 6).

General Information

Quackgrass seed production is relatively low, from 25-400 per stem (Timling 2000Footnote 7). Seed can remain viable in the soil for up to 5 years (Timling 2000Footnote 7). Quackgrass also reproduces rapidly by rhizomes, which can be spread in soil (CABI 2016Footnote 5).

Similar species

Western wheatgrass (Pascopyrum smithii)

  • The two species are similar in size, elongate shape and straw colour.
  • Western wheatgrass florets have a transverse groove at the base of the lemma, two lines of hairs on the callus and mixed long and short teeth on the palea. The rachilla is wedge-shaped and arises from a V-shaped sinus. The lemma and palea may be covered in a whitish bloom.

Slender wheatgrass (Elymus trachycaulus)

  • The two species are similar in size and elongate shape, although slender wheatgrass appears narrower than quackgrass.
  • Slender wheatgrass florets tend to be paler, purple-tinged and with a slight twist. The callus has a line of hairs at the base of the lemma. Palea teeth are fine and close together, and the rachilla is covered in long hairs.

Photos

Quackgrass (Couchgrass) (Elymus repens) florets
Quackgrass (Couchgrass) (Elymus repens) floret, palea view L, lemma view R
Quackgrass (Couchgrass) (Elymus repens) floret, close-up of palea teeth
Quackgrass (Couchgrass) (Elymus repens) floret, palea teeth
Quackgrass (Couchgrass) (Elymus repens) floret, close-up of rachilla
Quackgrass (Couchgrass) (Elymus repens) floret, side view, close-up of rachilla
Quackgrass (Couchgrass) (Elymus repens) florets

Similar species

Similar species: Western wheatgrass (Pascopyrum smithii) floret, palea view
Similar species: Western wheatgrass (Pascopyrum smithii) floret, palea teeth
Similar species: Western wheatgrass (Pascopyrum smithii) floret, callus (lemma view)
Similar species: Slender wheatgrass (Elymus trachycaulus) floret, palea view
Similar species: Slender wheatgrass (Elymus trachycaulus) floret, close-up palea teeth
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