Language selection

Search

Weed Seed: Ambrosia trifida (Giant ragweed)

Family

Asteraceae

Common Name

Giant ragweed

Regulation

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

Distribution

Canadian: Occurs in AB, MB, NB, NS, ON, PE, QC and SK. Reported as ephemeral in BC (Brouillet et al. 2016Footnote 1).

Worldwide: Native to North America and introduced to Asia (China, Georgia, Israel, Japan) and Europe (USDA-ARS 2016Footnote 2).

Duration of life cycle

Annual

Seed or fruit type

Achene within a bur

Identification features

Size

Shape

Surface Texture

Colour

Other Features

Habitat and Crop Association

Old fields, field margins, pastures, gardens, fencerows, shores, ditches, roadsides, railway lines, and disturbed areas (Darbyshire 2003Footnote 3, CABI 2016Footnote 4). A weed of many broadleaved crops (CABI 2016Footnote 4).

General Information

Dispersal of giant ragweed can occur through agricultural transport or roadside mowing (Von der Lippe et al. 2013Footnote 5) and it can also be a contaminant of bird and livestock feed (European Food Safety Authority 2010Footnote 6).

Giant ragweed is an aggressive weed of grain crops and no-tillage fields (Regnier et al. 2008Footnote 7). It is a major cause of hay fever (CABI 2016Footnote 4).

Similar species

Common ragweed (Ambrosia artemisiifolia)

Photos

Giant ragweed (Ambrosia trifida) burs
Giant ragweed (Ambrosia trifida) bur
Giant ragweed (Ambrosia trifida) bur
Giant ragweed (Ambrosia trifida) burs
Giant ragweed (Ambrosia trifida) bur, cross-section

Similar species

Similar species: Common ragweed (Ambrosia artemisiifolia) bur
Similar species: Common ragweed (Ambrosia artemisiifolia) burs
Report a problem or mistake on this page
Please select all that apply:

Thank you for your help!

You will not receive a reply. For enquiries, contact us.

Date modified: