Weed Seed: Galium verrucosum (Warty bedstraw)

Family

Rubiaceae

Common Name

Warty bedstraw

Regulation

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

Distribution

Canadian: Not present in Canada (Brouillet et al. 2016Footnote 1).

Worldwide: Native to southern Europe and the Mediterranean (Tutin et al. 1976Footnote 2, Hanf 1983Footnote 3). Naturalized in central Europe (Tutin et al. 1976Footnote 2) and in North America, it has been introduced in Michigan (USDA-NRCS 2016Footnote 4).

Duration of life cycle

Annual

Seed or fruit type

Schizocarp, divided into 2 fruits

Identification features

Size

  • Fruit diameter: 2.0 - 3.0 mm

Shape

  • Fruit is spherical, slightly compressed dorsiventrally

Surface Texture

  • Fruit surface is densely covered with tubercles

Colour

  • Fruit is pale green to straw yellow

Other Features

  • Hilum is located on the ventral side, and is marked by a small knot of tissue

Habitat and Crop Association

Cultivated fields, in scrub and degraded grassland (Hanf 1983Footnote 3).

General Information

Warty bedstraw seed has been introduced into Britain as a contaminant in imported caged bird food (Hanson and Mason 1985Footnote 5). Historically, it was recorded to occur rarely in corn fields (Lindley 1835Footnote 6).

Similar species

Cleavers (Galium aparine)

  • Cleavers are a similar size, a similar globose shape and bristles with an inflated base that appear similar to the rough surface of warty bedstraw.
  • Cleavers have tubercles that are white and translucent rather than the opaque yellowish tubercles of warty bedstraw. The hilum area is a deep hole rather than the tissue knot of warty bedstraw.

Photos

Figure 1 - Warty bedstraw (Galium verrucosum) schizocarp and fruits
Warty bedstraw (Galium verrucosum) schizocarp and fruits
Figure 2 - Warty bedstraw (Galium verrucosum) fruit, inner side
Warty bedstraw (Galium verrucosum) fruit, inner side
Figure 3 - Warty bedstraw (Galium verrucosum) fruit, outer side
Warty bedstraw (Galium verrucosum) fruit, outer side

Similar species

Figure 4 - Similar species: Cleavers (Galium aparine) fruits
Similar species: Cleavers (Galium aparine) fruits
Figure 5 - Similar species: Cleavers (Galium aparine) fruit
Similar species: Cleavers (Galium aparine) fruit
Figure 6 - Similar species: Cleavers (Galium aparine) fruit and tubercles
Similar species: Cleavers (Galium aparine) fruit and tubercles
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