Common Ragweed—Ambrosia artemisiifolia
A native annual, ragweed is valuable to many kinds of wildlife, but it produces large amounts of pollen, causing hayfever in those with allergies. It can be found in fields, gardens, along roadsides and vacant lots.
Grows upright, to 3 feet tall, with frequent branching. Agressive and persistent, the seeds remain viable for up to 80 years.
Flowers are small and grow in slender, elongated spikes. They are green when young, then turn yellowish green or brown. Flowers July–November.
Each flower is about 1/8 inch long. Male flowers produce a fine yellow pollen–each plant may produce up to 1 billion pollen grains.
Leaves up to 8 inches long, divided into many narrow, toothed segments, each segment pointed at the tip.
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Identification and Control Information
- Common Ragweed Description and Interesting Information—Illinois Wildflowers
- The Organic Weed Management Website—Cornell University
[Photos, left to right: Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org; Richard Old, XID Services, Inc., Bugwood.org; Steve Dewey, Utah State University, Bugwood.org; Joseph M. DiTomaso, University of California - Davis, Bugwood.org]