Spotted Knapweed

Plant Info

Also known as:
Scientific name:	Centaurea biebersteinii
Family:	Aster (Asteraceae)
Life cycle:	biennial or short-lived perenn
Origin:	Europe
Habitat:	sun; dry fields, along roads
Bloom season:	summer, fall
Plant height:	2 to 3 feet
USDA PLANTS database:	Minnesota county distribution map
Spotted in Ramsey County at:	Long Lake Regional Park Rice Creek Trail Corridor Vadnais/Snail Lake Regional Park

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Detailed Information

Flower:

Pink to purple, occasionally white, thistle-like flower heads 1 inch across. Each “petal” is tubular with 5 narrow lobes that fan out. The dark brown bracts under the flower head are tipped with black, supposedly giving the flower base a “spotted” appearance, hence the common name. A mature plant has 25 to 100 flowers.

Leaves:

Grayish blue-green somewhat hairy leaves are deeply lobed into narrow segments. Near the base of the plant leaves may be up to 8 inches long and 2 inches wide; they are much smaller near the top of the plant.

Notes:

Spotted Knapweed is on the noxious weed list for Minnesota. It tends to grow in colonies and contains poisons that prevent native plants from growing. The first year it sprouts, there is just a rosette of leaves, with flowers appearing the second year. One plant may live up to 5 years.

More photos

• a colony of Spotted Knapweed

Photos taken at Long Lake Regional Park, New Brighton, MN July 2007

Comments

Have you seen this plant in Ramsey County, or have any other comments about it?

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Please: Do not ask about where to buy seed or other gardening questions, are plants edible, etc. I am not a horticulturist or botanist, just an enthusiastic hobbyist so I probably don't know the answer. Please check the links page for additional resources. -thanks much

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