Weed Seed: Euphorbia esula (Leafy spurge)

Family

Euphorbiaceae

Common Name

Leafy spurge

Regulation

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

Distribution

Canadian: Occurs across Canada except in NL, NT and NU (Brouillet et al. 2016Footnote 1).

Worldwide: Native to central and eastern Europe and temperate Asia and introduced in northern Europe and North America (Canada, the United States and Mexico) (USDA-ARS 2016Footnote 2). In the United States it occurs across northern areas and into the southwest (Kartesz 2011Footnote 3).

Duration of life cycle

Perennial

Seed or fruit type

Seed

Identification features

Size

  • Seed length: 2.1 - 3.0 mm
  • Seed width: 1.5 - 2.3 mm

Shape

  • Oval-shaped seed; ends are slightly flattened

Surface Texture

  • Seed smooth, with a raphe on one side

Colour

  • Seed surface is usually light grey with reddish-brown mottles, but can be solid grey, orange or brown

Other Features

  • The hilum is usually covered by a caruncle

Habitat and Crop Association

Cultivated fields, pastures, rangelands, fields and roadsides (Royer and Dickinson 1999Footnote 4, Darbyshire 2003Footnote 5).

General Information

In the United States, leafy spurge is a particular problem in the northern and central plains states (CABI 2016Footnote 6). It prefers moist sites and disturbed soils and is aggressive in semi-arid situations or overgrazed pastures where competition is reduced. It can also establish in healthy natural ecosystems and in untilled, non-cropland habitats (CABI 2016Footnote 6).

Seed is dispersed by ejection from the capsule when ripe, up to a distance of 4.6 m. The seed may also be dispersed by water, wind, and animals. Seed in the soil may remain viable for up to eight years (CABI 2016Footnote 6).

Similar species

Cypress spurge (Euphorbia cyparissias)

  • The seeds of cypress spurge have a similar oval shape, grey colour and tissue over the hilum as leafy spurge.
  • Cypress spurge seeds (length: 2.0 - 2.5 mm; width: 2.0 - 2.3 mm) are generally shorter and wider than leafy spurge. Most are a solid light grey colour, but can be brown; all are without mottles.

Photos

Leafy spurge (Euphorbia esula) seeds
Leafy spurge (Euphorbia esula) seeds (top right) and capsules (bottom left)
Leafy spurge (Euphorbia esula) seed (with caruncle and raphe)
Leafy spurge (Euphorbia esula) seed (grey)
Leafy spurge (Euphorbia esula) seed, cross-section
Leafy spurge (Euphorbia esula) seed with mottles

Similar species

Similar species: Cypress spurge (Euphorbia cyparissias) seeds
Similar species: Cypress spurge (Euphorbia cyparissias) seed
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