Black Knapweed

Common Name: Black Knapweed

Specific Name: Centaurea nigra

Known Occurrence at Taylor Point:

Map areas: Cliffs 2E, Cliffs 2F, Woodlands 3D

Category: Non-Native, Invasive, Herbaceous Plant

Ecological Considerations:

Black Knapweed is a tall flowering thistle-like perennial plant that can grow from 1-3 feet high. A member of the daisy family, its leaves grow up to 10 inches long, and are usually deeply lobed, and hairy. The lower leaves are stalked. The upper ones are stalkless. The head bears many small bright purple flowers. Stems are many-branched and tipped by a solitary flower head up to 1 inch wide.

Black Knapweed grows well in moist soils alongside roads and river banks, in pastures, moist meadows, and on the edges of forests and throughout grassland habitats.

Problems Posed by this Plant:

Black Knapweed out-competes other plants in pastures, hayfields, meadows, riparian areas, forest margins, and rights-of-way, reducing overall biodiversity and forage quality. Centaurea nigra may also degrade soil and water resources by increasing erosion and surface runoff.

Native Species Affected by this Plant:

Factors Affording a Competitive Advantage to this Plant:

Propagation Mechanisms and Related Issues Affecting Efforts to Remove and/or Eliminate this Plant from Taylor Point:

Black Knapweed reproduces primarily by seed, although It also can be propagated by root crown fragments

Documented Best Removal Practices and Options/ Pros and Cons of Various Options:

Black Knapweed plants may be manually removed from the ground, ideally when the ground is wet, so long as care is taken to remove the entire plant, including the deep taproot. Mowing will reduce the number of flowers and seeds but will not eliminate the plants.

Case Studies of Removal Efforts, Lessons Learned and Recommendations: 

Additional Photos: