General: Branching plant with pink-purplish flowers in the Sunflower family.
Height: Grows between 0.2-1.8m tall.
Flowers: Flowering heads are single on the top of branching stems. The bracts under the petal area have a dark edge giving that area a spotted look. Flowers can sometimes be white.
Leaves/Stems: Erect stems that are often branching. Leaves in first year plants (rosette) are up to 15cm long and deeply lobed with smooth edges. Leaves grow out of the stem in an alternate pattern. Leaves become smaller near the top of the plant.
Diffuse knapweed and other knapweed species.
Differences: The main difference is that Spotted Knapweed has the dark edges of the floral bracts. Hybridization between Diffuse & Spotted knapweed can cause confusion. If it is hard to identify, please contact LRISS for assistance. There are other knapweeds with pink to purple flowers that should be reported.
Where did it come from? Europe.
Where does it grow here? Spotted knapweed is found in most places in our region. It prefers disturbed areas and can be found on roadsides, gravel pits and forestry landings. It will grow in areas that receive more moisture whereas Diffuse likes drier areas. This is why Spotted Knapweed is thriving in the Bridge River Valley area as well as the Marble Canyon as well.
Reproduction: By seed. One plant can produce 140,000 seeds in 1m2. Seeds can remain dormant and viable in the soil for up to 8 years.
When does it grow, flower & seed? Sprouts April-June. Flowers July-October. Seeds November.
Spreads By: Activities that disturb soil can spread Spotted Knapweed including road grading, road building, forest harvesting, and gravel extraction.
Plant Type: Perennial.
Southern Interior Weed Management Committee. 2016. Invasive Plants of the Southern Interior BC. 86pgs.
Okanagan Invasive Species Online website.