Weed Seed: Rumex spp. (Dock)

Family

Polygonaceae

Common Name

Dock

Regulation

Secondary Noxious, Class 3 in the Canadian Weed Seeds Order, 2016 under the Seeds Act, with the exception of Rumex maritimus and Rumex acetosella.

Distribution

Canadian: Occurs in all Canadian provinces and territories (Brouillet et al. 2016Footnote 1).

Worldwide: Native to northern Africa, Asia and Europe (USDA-ARS 2016Footnote 2). Naturalized in southern and eastern Africa, southeastern Asia, Australia, New Zealand, North America and South America (USDA-ARS 2016Footnote 2). Widespread in the United States (USDA-NRCS 2016Footnote 3).

Duration of life cycle

Annual, Biennial or Perennial; most are perennial

Seed or fruit type

Achene, may be in a perianth

Identification features

Size

  • Achenes of Rumex spp. vary in size, most species are a medium length (2.0 - 3.0 mm)
  • Rumex maritimus:
    • Achene length: 1.2 - 2.0 mm
    • Achene width: 0.8 - 1.0 mm
  • Rumex acetosella:
    • Achene length: 1.3 - 2.0 mm
    • Achene width: 1.0 - 1.3 mm

Shape

  • Achenes of Rumex spp. are trigonous, ovate, sharp-edged with a rounded base and a pointed top
  • Rumex maritimus achenes trigonous, long oval, pointed at both ends
  • Rumex acetosella achenes trigonous with rounded edges, ovate, pointed at top end

Surface Texture

  • Achenes of Rumex spp. are smooth, with a satin sheen

Colour

  • Achenes of Rumex spp. are a shade of brown, most are reddish-brown
  • Achenes of R. maritimus are medium brown; achenes of R. acetosella are reddish-brown

Other Features

  • Achenes of Rumex spp. may be shed within a perianth, loosely fitting and often removed during processing
  • Rumex spp. perianth is papery, dull, reddish-brown, trigonous with a tubercle on each side
  • Perianth of R. maritimus has long teeth on the margins and a tubercle on each face
  • Perianth of R. acetosella is reddish-brown, roughened, no tubercles and tight to the achene

Habitat and Crop Association

Meadows, pastures, roadsides, fencerows and waste places (Frankton and Mulligan 1993Footnote 4). Some species, such as R. crispus, are weeds of cultivated fields and pastures (Royer and Dickinson 1999Footnote 5).

General Information

There are 34 species of dock present in Canada, of which 20 are native and 14 are introduced (Brouillet et al. 2016Footnote 1). Most of these species are very difficult to identify by the achene. It usually requires the presence of the perianth for species identification but this is usually removed during processing in commercial grain lots.

Some Rumex species that are widespread in Canada show regional abundance in certain provinces; R. pseudonatronatus is most commonly found in Alberta and Saskatchewan, R. longifolius is abundant in Ontario, Quebec, and New Brunswick (Darbyshire 2003Footnote 6). Rumex crispus is found throughout Canada and the United States (Government of British Columbia 2002). R. obtusifolius is found in most western states in the U.S. (DiTomaso et al. 2013Footnote 7).

Similar species

Rumex spp.

  • The achenes of commonly encountered Rumex species, such as R. crispus and R. pseudonatronatus, are medium length (2.0 - 3.0 mm), the achenes are ovate-shaped, trigonous, smooth surface and a reddish-brown colour.
  • The perianth of common Rumex species fits loosely, reddish-brown, papery, dull and trigonous with entire or toothed edges. A tubercle is usually attached to each side.
  • Achenes of R. maritimus are pointed at both ends, medium-brown and smaller than commonly encountered species.
  • Achenes of R. acetosella have a similar ovate shape and reddish colour as other Rumex spp., except for their smaller size and rounded edges.
  • The perianth of R. maritimus is reddish brown, papery with tubercles like Rumex spp., but has distinctive long teeth on the edges.
  • The perianth of R. acetosella is reddish brown and papery, but is tight-fitting, without teeth or tubercles.

Photos

Curled dock (Rumex crispus) achenes and perianths
Curled dock (Rumex crispus) achene
Curled dock (Rumex crispus) achene
Curled dock (Rumex crispus) achene, cross-section
Bitter dock (Rumex obtusifolius) achenes
Bitter dock (Rumex obtusifolius) achene
Field dock (Rumex pseudonatronatus) achenes and perianths
Field dock (Rumex pseudonatronatus) achene
Dock (Rumex sp.) seed, cross section
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