Calflora
Taxon  Report   300    
Ambrosia trifida  L.
Giant ragweed
Ambrosia trifida
© 2008 Louis-M. Landry
Photos from
CalPhotos / Calflora
Ambrosia trifida
© 2001 CDFA
Ambrosia trifida
© 2015 Richard Spellenberg
Ambrosia trifida, a dicot, is an annual herb that is not native to California; it was introduced from elsewhere and naturalized in the wild. There is a high risk of this plant becoming invasive in California according to Cal-IPC.

Interactive Distribution Map


Observation Hotline
(observation details + photos)



point, line, or polygon

one or more occurrences
within a 7.5-minute quadrangle

Plant Characteristics
and Associations



Bloom Period
Ambrosia trifida
© 2010 Jean Pawek
Family: ASTERACEAE  
Genus: Ambrosia
Communities: weed, characteristic of disturbed places, wetland-riparian

Wetlands: Equally likely to occur in wetlands and non wetlands

Habitat: disturbed

Name Status:
Accepted by JEF + PLANTS

Alternate Names:
ICPN: Ambrosia trifida var. trifida
More information about  Ambrosia trifida
Photos on PlantID.net   /   Google Images
Jepson eFlora

Records from the Consortium of California Herbaria

ITIS Original Publication citation

USDA PLANTS Profile (AMTR)

Search the International Plants Names Index

Search efloras.org (Flora of North America)

website references from Google


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]. 2018. Berkeley, California: The Calflora Database [a non-profit organization].
Available: https://www.calflora.org/   (Accessed: Nov 17, 2018).

The information on this page comes from diverse sources. None of the links are sponsored.