(reprinted with permission from Colorado Weed Management Association)

Non-native and Unchallenged

What distinguishes noxious weeds from other plants is that they are not native to the United States, and they grow unchecked by natural predators and enemies such as insects or diseases. In their native environment, these forces prevent the plant from becoming a problem.

How Noxious Weeds Spread

Noxious weeds become established in soils disturbed by a variety of activities such as construction, motorized vehicles, road maintenance, recreation, improper livestock grazing, and natural disturbances such as fire. Noxious weed seeds are transported to new sites in numerous ways such as wind, water, tires, people, as well as wild and domestic animals.

Environmental Impacts from Noxious Weeds

Biodiversity and ecosystem stability are threatened by noxious weeds. A common characteristic of all noxious weeds is their aggressive, competitive behavior. Typically, they steal precious moisture, nutrients, and sunlight from the surrounding plants. Noxious weeds also alter soil properties, the composition of plant communities, and change the structure of animal communities. Native animals are unable to adapt to using the noxious weeds for food, shelter, or nesting.

Noxious weeds are expanding exponentially in the inter-mountain West. (Courtesy Bureau of Land Management)

Of the 3,000 native species of plants in Colorado, 500 or 17% have already been displaced by noxious weeds.