Ambrosia trifida

Ambrosia trifida_C022-07
Photo courtesy UC Davis Weeds of California

Common names: giant ragweed

Ambrosia trifida (giant ragweed) is an annual herb/ (family Asteraceae) with a long cluster of green-yellow flowers and opposite leaves found in the central western and southwestern areas of California. Giant ragweed has both female and male flower parts. It is native to the central and eastern United States. It favors grasslands. It spreads via seeds, and easily resprouts after being cut.

Cal-IPC Rating: Watch

CDFA Rating: B*

Cal-IPC Assessment

Plant Risk Assessment - An evaluation of the potential for a plant to be invasive in California.

Weed Management Notes

No Weed RIC Management Notes are available for this species. Check for information on other species in the genus on the Weed RIC site.

Cal-IPC Newsletter Articles

There are no newsletter articles associated with this species yet.

Cal-IPC Symposium Presentations

Presentations are linked where available. Where a presentation is not available, find more information by reading the abstract in the Cal-IPC Symposia Archive.

There are no Symposium presentations associated with this species yet.

Other Ambrosia trifida Information

  • CalPhotos - Images of plants taken mostly in California.
  • Calflora - See the distribution of this species on Calflora's map of California.
  • Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
  • CDFA - California official noxious weeds.
  • USDA PLANTS Database - Federal database with information on identification and distribution, and links to websites in individual states.
  • EDDMapS - North American distribution based on Early Detection and Distribution Mapping System.