State Noxious Weed List -No

Growth form: Taprooted annual forb which grows 1 to 3 feet tall. Leaves are deeply divided, pubescent, and opposite lower on the stem becoming alternate above. The flowers are small, yellow-green in color and produced in racemes. The plant is monoecious with male flowers above the female flowers. Seeds are enclosed in a hard bur.

Ragweed pollen is considered the number one cause of hay fever in the late-summer and fall. Each plant can produce over a billion grains of pollen per season which occurs from mid-August until frost. Ragweed flourishes during dry hot summers.

This plant is a native species common through out the region usually in waste or disturbed areas and over-grazed rangeland. Western ragweed (A. psilostachya DC.) is also found in the region, but it is a perennial with less finely divided leaves.