Weed profile: Knapweed
Black knapweed
Black knapweed
Centaurea spp.
The knapweeds have over 500 species. Many are commonly grown in the garden (e.g. cornflowers) without risk of weediness. However, others are noxious weeds including:
- Spotted knapweed, C. maculosa
- Black knapweed, C. nigra
- Star thistle, C. calcitrapa
- St Barnaby’s thistle, C. solstitialis
The plants are not readily eaten by livestock and compete with useful pastures, possibly with allelopathic effects. That is, by producing chemicals these plants suppress growth of other species. This in turn reduces the carrying capacity of the land.
Status
- Declared in NSW under the Noxious Weeds Act 1993 (C. calcitrapa: view details, C. maculosa: view details, C. nigra: view details, C. solstitialis: view details)
Related publications
| Title | |
|---|---|
| Knapweed (Weed Alert) |  303.0 kb |