- 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.
- 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.
- 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.
- 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.
- Weed of the Week - USDA Forest Service
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EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit www.eddmaps.org
State Invasive List - This map identifies those states that list this species on their invasive species list. For more information, visit Invasive.org
Invasive Listing Sources
- Faith Campbell, 1998
- Great Lakes Early Detection Network
- Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
- Mid-Atlantic Exotic Pest Plant Council, 2005
- Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
- Pacific Northwest Exotic Pest Plant Council, 1998
- Washington Noxious Weeds
- WeedUS - Database of Plants Invading Natural Areas in the United States
|Common Name Reference:|| USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.|
|Scientific Name Reference:||USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.|