Diffuse Knapweed
Diffuse Knapweed
Centaurea diffusa Lam.
Asteraceae (Sunflower Family)
▲ ▼ seedlings
▲ ▼ seedlings
▲ ▼ young plants
▲ ▼ young plants
▲ ▼ young plants
▲ ▼ first year rosettes
▲ ▼ mature, flowering plants
▲ flowering stem showing white flowers
▲ ▼ inflorescences, with above showing the comb-like spines on the bracts
▲ ▼ inflorescences
▲ ▼ large colonies of diffuse knapweed in Arizona
Centaurea diffusa Lam., Diffuse Knapweed: (Bayer Code: CENDI; US Code CEDI3)
- Annual, biennial or perennial, with basal rosette followed by much-branched flowering stems
- Basal leaves leaves similar to spotted knapweed
- Has inflorescence with 12-13 white ray flowers per head and tan, comb-like, toothed bracts under inflorescence
- Not common in eastern Midwest, but common in near & west of Rocky Mountains
- Highly-invasive in open prairie and rangeland soils, plus is allelopathic to other plants
- Prefers full sun, well-drained soils
- Similar species:
- Spotted knapweed (Centaurea stoebe) has similar basal leaves, but has pink flowers and a dark spot on the bracts below the flower head
- Squarrose knapweed (Centaurea virgata) has somewhat similar leaves and also has tan, comb-like bracts below the head, but squarrose knapweed’s bract tips point away more from the head, plus squarrose knapweed has pink flowers
(Updated January 19, 2019)