Knapweed
Knapweed (one of several Knapweed varieties) is a member of the aster family of flowers and was introduced accidentally from Central Asia. It is a serious problem to rangeland and very invasive to roadsides and fields in general.
NOTE: Diffuse and Spotted Knapweed actually secrete a natural herbicide into the soil to eliminate competition.
To the farmer or rancher, Knapweeds are an economic problem because they are unpalatable, inedible and low-nutrient weeds. There are 25 species of Knapweed in North America and two of that cause the biggest problems.
Diffuse Knapweed reproduces from seed only, can live up to 3 years as a perennial, and reaches heights up to 2-1/2 feet. It has white or pink to purple flowers.
Spotted Knapweed can reproduce from seed or vegetative from shoots growing near the surface. It grows up to 3 feet tall and has purple or white flowers.
Both Diffuse and Spotted Knapweeds spread rapidly for the following reasons:
1- They quickly establish themselves in soil that has been disturbed by vehicles.
2- They reproduce rapidly from seed with a single plant having 16 seed heads.
3- They have very long tap roots to search for water. |