Summary ³

Ambrosia trifida, the giant ragweed, is a species of flowering plant in the sunflower family. It is native to North America, where it is widespread in Canada, the United States, and northern Mexico. It is present in Europe and Asia as an introduced species, and it is known as a common weed in many regions.

Description ⁴

Family:
Asteraceae (Aster)

Height:
3 to 12 feet

Leaves:
Large with 3 or 5 distinct lobes. Arranged oppositely on stem.

Flower:
Small, yellowish green flowers on male plants, indistinct on female.

Bloom time:
July-September

Nicknames:
Great Ragweed, Horseweed

Habitat:
Fields, disturbed soils, roadsides

Can I plant this in my garden?
No, giant ragweed is considered weedy. Many people are allergic to its pollen, which causes hay fever.

References:
https://www.minnesotawildflowers.info/flower/giant-ragweed

Range ⁴

Sources and Credits

1. (c) gwen_cox, some rights reserved (CC BY-NC)
2. (c) Ramsey-Washington Metro Watershed District, all rights reserved, uploaded by Ramsey-Washington Metro Watershed District
3. Adapted by Ramsey-Washington Metro Watershed District from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Ambrosia_trifida
4. (c) Ramsey-Washington Metro Watershed District, some rights reserved (CC BY-SA)

More Info

• iNaturalistAU taxon page
• Biodiversity Heritage Library
• BOLD Systems BIN search
• Calflora
• CalPhotos
• eFloras.org
• Flora of North America (beta)
• Global Biodiversity Information Facility (GBIF)
• Go Botany
• HOSTS - a Database of the World's Lepidopteran Hostplants
• IPNI (with links to POWO, WFO, and BHL)
• Jepson eFlora
• Maryland Biodiversity Project
• NatureServe Explorer 2.0
• NBN Atlas
• OregonFlora.org
• SEINet Symbiota portals
• Tropicos
• USDA PLANTS database
• VASCAN by Canadensys
• World Flora Online
• 日本のレッドデータ検索システム
• 植物和名−学名インデックス YList

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