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ragweed (Ambrosia arteminiifolia)
ODA rating: B
USDA Symbol: AMAR2
Oregon ragweed distribution
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Images courtesy of Western Society of Weed Science.

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Annual; blooms late summer. Grows to 4 foot tall. Stems and leaves blue-green and covered with fine hairs. Leaves divided and bottom sides covered in fine hairs, giving a gray appearance. Flowers inconspicuous and found on terminal branches.
This plant is common throughout the West and causes hay fever in many people. It is commonly found along ditches and waste areas. It is not highly competitive in crops or rangeland.
Distribution in Oregon
The first documented site of this plant in Oregon was 1909 in Josephine County.

Biological controls
No approved biological control agent is available.