meadow knapweed: Centaurea x moncktonii (Asterales: Asteraceae): Invasive Plant Atlas of the United States

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.org

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Plant(s); in flower Cindy Roche, , Bugwood.org Additional Resolutions & Image Usage	Stand; Eric Coombs, Oregon Department of Agriculture, Bugwood.org Additional Resolutions & Image Usage	Flower(s); In July Great Smoky Mountains National Park Resource Management , USDI National Park Service, Bugwood.org Additional Resolutions & Image Usage	Flower(s); Eric Coombs, Oregon Department of Agriculture, Bugwood.org Additional Resolutions & Image Usage
Flower(s); Eric Coombs, Oregon Department of Agriculture, Bugwood.org Additional Resolutions & Image Usage	Flower(s); seedhead Cindy Roche, , Bugwood.org Additional Resolutions & Image Usage	Flower(s); Eric Coombs, Oregon Department of Agriculture, Bugwood.org Additional Resolutions & Image Usage	Flower(s); Eric Coombs, Oregon Department of Agriculture, Bugwood.org Additional Resolutions & Image Usage
Flower(s); Eric Coombs, Oregon Department of Agriculture, Bugwood.org Additional Resolutions & Image Usage	Flower(s); purple with white ray flowers Eric Coombs, Oregon Department of Agriculture, Bugwood.org Additional Resolutions & Image Usage	Flower(s); white color morph Eric Coombs, Oregon Department of Agriculture, Bugwood.org Additional Resolutions & Image Usage	Flower(s); hybrid with diffuse knapweed Eric Coombs, Oregon Department of Agriculture, Bugwood.org Additional Resolutions & Image Usage

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 List
This map identifies those states that list this species on their invasive species list or law.

Invasive Listing Sources: