Diffuse knapweed is a biennial or short-lived perennial with a well-developed taproot and highly branched stems. It was ntroduced to North America from Eurasia near the beginning of the 20th century, likely through alfalfa seeds (Roche and Roche 1999). It grows to 60 cm tall and has white, lavender, or purple composite flowers.

Biennial or short-lived perennial

It is found in a variety of dry habitats particularly in disturbed areas and does not tolerate shade. It is generally not found in cultivated or irrigated fields. Diffuse knapweed is unpalatable to livestock and can cause serious loss of forage production on heavily infested rangelands.

Diffuse knapweed reproduces exclusively from seeds and a single plant can produce up to 18,000 seeds. Most seeds fall close to the parent plant, but adult plants may distribute seeds when they break off at the root collar or lower stem and tumble for a considerable distance blown by the wind. Seeds can remain viable in the soil for many years.

Scattered throughout the region but heaviest along Highway 97 and at Green Lake, Konni Lake, and in Tatlayoko Valley. There is a large infestation to the south and east of our region.