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Centaurea jacea is a perennial plant that grows 1-4 ft. (0.3-1.2 m) tall. The stems are ridged and may have purple stripes.

Foliage

The basal leaves are oblanceolate to elliptic and 2-10 in. (5 -25 cm) long. Leaves become smaller as they ascend the stem. These smaller leaves are lanceolate and attach directly to the stem.

Flowers

The brown bracts of the inflorescence give this plant its common name. Flowering occurs from June to October, when rose to purple flowers appear in 1-1.25 in. (2.5-3.2 cm) wide, solitary heads at the tips of the branches.

Fruit

Centaurea jacea produces small light brown, plumeless seeds; about 12 per head.

Ecological Threat

Centaurea jacea is an aggressive invader preferring moister, cooler conditions than other knapweed species. It can tolerate partial shade. It can invade grasslands, open woods, meadows, pastures, woodland clearings, and cutover areas of forest crowding out native plants or forage. Centaurea jacea is native to Europe.

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Fri, 29 Mar 2024 02:16:09 -0400 Fri, 29 Mar 2024 02:16:09 -0400 http://Images.bugwood.org/ <![CDATA[brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=1350057 brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=1350057 <![CDATA[brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=1350056 brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=1350056 <![CDATA[brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436650 brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436650 <![CDATA[brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436654 brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436654 <![CDATA[brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436657 brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436657 <![CDATA[brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436658 brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436658 <![CDATA[brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436660 brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436660 <![CDATA[brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436664 brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436664 <![CDATA[knapweeds Centaurea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5474971 knapweeds Centaurea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5474971 <![CDATA[knapweeds Centaurea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5474972 knapweeds Centaurea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5474972 <![CDATA[knapweeds Centaurea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5474974 knapweeds Centaurea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5474974 <![CDATA[brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436663 brown knapweed Centaurea jacea]]> http://www.ipmimages.org/browse/detail.cfm?imgnum=5436663