CITY AND COUNTY OF BROOMFIELD PARK OPERATIONS
NOXIOUS WEED IDENTIFICATION
RUSSIAN KNAPWEED, Centaurea repens, L.
Characteristics:
Family: Asteraceae (Sunflower)
Origin: Eurasia
Description:
- Perennial
- Forms dense patches with extensive root systems
- Reproduces by seeds and root stock
- Roots often have a black papery or bark like covering
Stems:
- Multiple branching, erect stems
- Grows up to 3 feet tall
Flowers:
- Lavender in color, with white papery covered bracts
- 1/2 inch in diameter, which occur single at the tip of branched stems
- Bloom occurs June-August
- Seeds are produced late summer into the fall
Leaves:
- Lower leaves are larger and notched. Upper leaves have progressively less notches
- Leaves are less than 4 inches and vary with climatic variables
Location:
Russian Knapweed is often found along roadways, ditch banks, in waste areas and pastures. It is poisonous to horses, killing many every year. It is easily distinguishable from diffuse knapweed by comparing bracts. Diffuse Knapweed is bristly to the touch, while Russian Knapweed is smooth and pearly in color. This noxious weed is very difficult to eradicate. Many years of watchful control is required.