SafePlants

Meadow Knapweed

Meadow Knapweed is a complex group of plants with a few different accepted scientific names, reflecting its hybrid origin and variable characteristics. Understanding its nomenclature and biology is crucial for managing its spread.

Scientific Name and Synonyms:

• Accepted Scientific Name: Depending on the source, the scientific name may be Centaurea pratensis, Centaurea × moncktonii, or Centaurea jacea × nigra.
• Synonyms: Centaurea moncktonii syn. C. pratensis, C. debeauxii, Centaurea jacea nothosubsp. pratensis

Taxonomy and Nomenclature:

• Family: Asteraceae (Sunflower family)
• Origin: It is noted as a fertile hybrid between brownray knapweed (Centaurea jacea) and lesser or black knapweed (Centaurea nigra). Some sources also indicate it's a hybrid of black (C. nigra) and brown (C. jacea).

Considerations for Pets and Children:

• This plant can displace desirable forage plants, so it may be unpalatable to some animals.

Distribution and Habitat:

• Origin: Native to Europe.
• Distribution: It has expanded its distribution to 27 of the United States and is also found in parts of North America.
• Habitat: It can grow in a wide range of environmental conditions including roadsides, sand/gravel bars, river banks, irrigated pastures, meadows, and forest openings.

Ecological Role:

• Invasive Species: Meadow Knapweed is considered an aggressive invasive species.
• Impact: It outcompetes desirable forage plants and native plant communities, reducing forage for wildlife and livestock. It also threatens wildlife habitat and interferes with Christmas tree plantations.

Morphological Characteristics:

• Growth Habit: It is a perennial plant that grows from a woody crown or root crown.
• Height: The plant grows to 20-40 inches tall or up to 3 1/2 feet tall.
• Stems: It has multiple upright, reddish stems that branch about halfway up. The stems are sometimes described as stiff.
• Leaves: Leaves can grow to be about 6 inches long and 1 1/2 inches wide. The leaves near the base are slender.
• Flowers: Single flowers are located at the tips of stems. They are mostly pink/purple but occasionally white. The flowers are characterized by light to dark brown fringed bracts.

Interactions with Other Organisms:

• Knapweed is noted as a favorite of pollinating insects.

Common Names:

• centaury, centory, starthistles, knapweeds, hardheads, black knapweed, hybrid knapweed

Further Information:

• USDA symbol: CEDE5
• ODA rating: B
• Resources: Field Guide for Managing Diffuse, Meadow, Spotted, and Squarrose Knapweeds in the Southwest. Forest Service. September 2014. Southwestern Region. A species profile for Diffuse Knapweed from USDA's National Invasive Species Information Center.
• Images: Bugwood.org (Cindy Roche, Eric Coombs)