Grazing Oklahoma: Western Ragweed (Ambrosia psilostachya)

By Mike Proctor

Characteristics: Western ragweed (or Cuman ragweed) is a very common forb in the Southern Great Plains. It is a warm-season perennial with extensive rhizomes that can form large colonies. The leaves are rough with deep lobes. The flowers occur in spikes at the top of the plant, while the female flowers are found in small clusters at the base of the spike.

Area of importance: Western Ragweed occurs throughout most of the United States, into Canada and Mexico. It is native to the Great Plains but occurs as a weed elsewhere. Western ragweed becomes most abundant on sites that have shallow or poor soils and on areas that have a history of being overgrazed. You may find it on more productive sites, but competition with other species keeps it in check.

Learn more in the September issue of OKFR.