meadow knapweed USDA PLANTS Symbol: CEMO6
U.S. Nativity: Exotic
Habit: Forbs/Herbs
Centaurea x moncktonii C. E. Britton[C. jacea X C. nigra]

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Taxonomic Rank: Magnoliopsida: Asterales: Asteraceae

Appearance
Centaurea x moncktonii is an herbaceous, perennial weed, living 3-5 years on average. It is a fertile hybrid between brownray knapweed and lesser knapweed. It is usually bushy with erect stiff branches and grow from 1-4 ft (0.3-1.22 m) tall. It is native to Europe. It has been found across the United States and Canada.
Foliage
Leaves are up to 6 in. (15.2 cm) long and 1 in. (2.5 cm) wide and decrease in size as they move up the stem. The lower leaves are toothed or lobed and the upper leaves are linear.
Flowers
Flowering occurs in May to August, sometimes later if it is mowed. Flowers are pink to purple, contained in heads and located at the tips of the branches. Each is about the size of a nickel and much rounder than spotted knapweed flower heads. Bracts around the flower head are light to dark brown, with a thin fringed margin. The bracts look shiny and coppery once the flowers are mature.
Fruit
The plant reproduces by seed and is shed immediately one it is mature. Seed production is prolific with from 1,000-25,000 seed per plant a year. Seed can survive in the soil seed bank for over five years.
Ecological Threat
Caution: All Centaurea spp. contain carcinogens, always wear gloves and use caution when handling these plants.Centaurea x moncktonii grows best along moist roadsides, sand/gravel bars and river banks, irrigated pastures, moist meadows, and forest openings.

Selected Images from Invasive.orgView All Images at Invasive.org


Plant(s); in flower
Cindy Roche, , Bugwood.org
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Stand;
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
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Flower(s); In July
Great Smoky Mountains National Park Resource Management , USDI National Park Service, Bugwood.org
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Flower(s);
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
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Flower(s);
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
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Flower(s); seedhead
Cindy Roche, , Bugwood.org
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Flower(s);
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
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Flower(s);
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
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Flower(s);
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
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Flower(s); purple with white ray flowers
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
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Flower(s); white color morph
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
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Flower(s); hybrid with diffuse knapweed
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
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EDDMapS Distribution:
This map is incomplete and is based only on current site and county level reports made by experts and records obtained from USDA Plants Database. For more information, visit www.eddmaps.org
 


State(s) Where Reported invasive.
Based on state level agency and organization lists of invasive plants from WeedUS database.


Invasive Listing Sources:
California Invasive Plant Council