Vochin Knapweed
Centaurea nigrescens
Washington State Classification
Class A — Eradication Required Statewide
Vochin knapweed invades pastures and natural areas, competing with native plants and forage.
Quick Reference
Identification
Growth Habit
Vochin knapweed is a perennial growing from 19 inches to 5 feet (30 to 150 cm) tall. Stems are upright and branched and typically covered in hairs. Flowers from summer to fall.
Leaves
Basal leaves have stalks and are oval to narrow, with the widest point above the middle. Margins smooth, toothed or irregularly lobed. When lobed, the rounded terminal lobe is larger than other lobes. Stem leaves become smaller moving up the stem.
Flowers
Flowerheads narrow in few-headed clusters. Bracts at base of flower head with small dark triangular tips, having 6 to 8 small fringes per side. Flowerheads of 40 to 100+ purple (or white) flowers with the outer ring of flowers being sometimes larger.
Fruit & Seeds
Seeds are gray to light brown and up to 0.14 inches (3.5 mm) long. Seeds may or may not have short bristles (pappus) on one end.
Impact
Vochin knapweed invades pastures and natural areas, competing with native plants and forage.
Ecology & Spread
Habitat
Vochin knapweed grows along roadsides, in irrigation ditches, pastures, orchards and waste places In Washington it has been found in cleared areas. Please click here to see a county level distribution map of vochin knapweed in Washington.
Spread Mechanisms
Reproduction
Vochin knapweed is a perennial that reproduces by seed and can be propagated by root division.
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Control Methods
Mechanical
- Small infestations can be controlled by repeatedly digging out the plant. Dig out as much of the plant as possible and watch for re-sprouting from root fragments.