Calflora, a 501c3 non-profit
Distribution by County   300    
Ambrosia trifida  L.
Giant ragweed
Ambrosia trifida is an annual herb that is not native to California.
There is a high risk of this plant becoming invasive in California according to Cal-IPC.
Record Count by County

Contra Costa: 6 Los Angeles: 1 San Diego: 3 Siskiyou: 1
Glenn: 1 Monterey: 2 San Joaquin: 1
Lassen: 1 Orange: 2 San Mateo: 1

Suggested Citation
Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria. [web application]. 2023. Berkeley, California: The Calflora Database [a non-profit organization]. Available: https://www.calflora.org/   (Accessed: 06/03/2023).