Brownray knapweed (Centaurea jacea)

Brownray knapweed Common Names: Brown knapweed, Rayed knapweed

Description: Often found as a hybrid of Black knapweed (Centaurea nigra).

Habit: Perennial with a woody root crown that grows 20-48 in tall and branching near the top.

Leaves: Basal, 6 in long, tapering at both ends with the broadest part above the middle of the leaf. Stem leaves are lance-shaped, shallowly-lobed and stalkless.

Stems: Ridged and sometimes purple-striped, grows 20-48 in tall.

Flowers: Rose to purple but rarely white in color, 3/4 - 1 in light brown to dark brown flower heads are found at the ends of the branches. Hairy bracts are wider at the tips with broad, thin, papery margins. Center of bracts is a dark brown color. Bract tips overlap the base of nearby bracts. Blooms from July to October.

Fruit and seeds: Seeds are tan; small with fine hairs and no pappus.

Habitat: Native to Eurasia. Found in grasslands, open woods, meadows, pastures, woodland clearings, and in cutover areas of forests.

Reproduction: By seed.

Similar species: Other species of Knapweeds (Centaurea spp.).

Monitoring and rapid response: Pull or dig up small infestations including the entire root system if possible. Plants that are periodically mowed will generally continue to flower and produce seed on short plants below mower blade. Effectively controlled using any of several readily available general use herbicides such as glyphosate. Natural enemies include Gall flies (Urophora affinis and Urophora quadrifasciata) that feed on the developing seed heads and dramatically reduces seed production.

Credits: The information provided in this factsheet was gathered from the U.S. Forest Service.

Individual species images that appear with a number in a black box are courtesy of the Bugwood.org network (http://www.invasive.org).Individual photo author credits may not be included due to the small display size of the images and subsequent difficulty of reading the provided text. All other images appear courtesy of Google (http://images.google.com).


Common Name:

Brownray knapweed

Scientific Name:

Centaurea jacea

Family:

Asteraceae
(Aster)

Duration:

Perennial

Habit:

Herbs

USDA Symbol:

CEJA
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