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great ragweed

Scientific Name: Ambrosia trifida

Family: Asteraceae

Category: Dicot

Growth: Subshrub, Forb/herb

Duration: Annual

Other Names:

       

Giant Ragweed (Ambrosia trifida)

Ambrosia trifida, commonly known as giant ragweed or great ragweed, is a widespread plant native to North America and belongs to the sunflower family.

Considerations for Pets

  • The plant can grow quite tall (3-12 feet), and its presence in gardens or disturbed areas may be common.

Considerations for Children

  • The plant can grow quite tall (3-12 feet), and its presence in gardens or disturbed areas may be common.

Taxonomy and Nomenclature

  • Scientific Name: Ambrosia trifida L.
  • Family: Asteraceae (or Compositae), also known as the Sunflower family.
  • Synonyms and Common Names: Giant Ragweed, Great Ragweed, Texan great ragweed, Bitterweed, Bloodweed, Buffalo Weed, Horse Cane, Kinghead, Tall ragweed, Horseweed, Tall Ambrosia, Crown Weed, grande herbe à poux.

Distribution and Habitat

  • Native to North America.
  • Widespread in Canada and most of the continental U.S. (except Nevada).
  • Commonly found in disturbed areas, such as streambanks, fields, gardens, and roadsides.

Ecological Role

  • Can be invasive, particularly in disturbed areas.
  • Pollen is a significant allergen, causing hay fever in many individuals.
  • Impacts crop production in agricultural settings.

Morphological Characteristics

  • Summer annual that grows to 3-12 feet tall, branching occasionally.
  • Green stems covered with white hairs.
  • Opposite leaves.
  • Flowers are small, yellow to greenish, and petal-less, arranged in spike-like racemes.

Quirky Facts

  • The genus name "Ambrosia" is derived from the Greek word for the food of the gods, an ironic name considering its allergenic properties.
  • Giant ragweed leaves, when they first emerge, can be mistaken for those of sunflowers or sunchokes, to which it is closely related.

Interactions with Other Organisms

  • Wind-pollinated.
  • Pollen causes hay fever in humans.
  • Can impact crop yields, causing reduced production for farmers.
  • Becoming increasingly resistant to herbicides like glyphosate.

Further Information

  • Dave's Garden: A community for sharing gardening tips and ideas.
  • Purdue Extension: Offers resources on the biology and management of giant ragweed.
  • Nature Manitoba: Provides information on Manitoba wildflowers.
  • bioimages.vanderbilt.edu: Image database hosted by Vanderbilt University.