Ambrosia artemisiifolia L. - Common Ragweed


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Ambrosia artemisiifolia - (image 1 of 3)



Family: Asteraceae


Disturbed sites. Waste ground.




All of the continental US.


Annual to 1 m, usually shorter. Leaves once or twice pinnate, opposite near base of the plant, becoming alternate towards the top. Plants monoecious, with the pistillate heads borne below staminate heads in the axils of leaves or bracts. Staminate heads in racemiform inflorescences.


Flowers August to October

Wetland Indicator: Facultative Upland

The common name of this plant is well-known to allergy sufferers. Some people think of goldenrods as ragweed, presumably because they assume bright flowers seen in the fall are the source of drifting pollen. However, plants with wind-disseminated pollen typically do not have brightly colored flowers.

This plant can be very common where the soil has been disturbed, particularly around buildings, in gardens, fields and parking lots.


Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Second Ed.
The New York Botanical Garden. Bronx, NY


Swink, F. and G. Wilhelm. 1994. Plants of the Chicago Region.
Indiana Academy of Science. The Morton Arboretum. Lisle, Illinois.




Michael Hough 2004