Centaurea stoebe (Spotted Knapweed)

Plant Info
Also known as:
Genus:Centaurea
Family:Asteraceae (Aster)
Life cycle:biennial, short-lived perennial
Origin:Europe
Status:
  • Invasive - ERADICATE!
  • Noxious Weed
  • Prohibited or Restricted species
Habitat:sun; dry fields, roadsides, waste areas
Bloom season:June - October
Plant height:2 to 3 feet
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: 7+petals Flower shape: tubular Cluster type: panicle Cluster type: round

[photo of flowers] Pink to purple, occasionally white, thistle-like flower heads 1 inch across at the end of branching stems. Each head is made up of many tubular flowers with 5 narrow lobes that fan out.

[photo of bract] The bracts under the flower head also resemble those of a thistle and are green or brown tipped with brownish black, with coarse hairs all around the edge of the tip. A mature plant has 25 to 100 flower heads.

Leaves and stem: Leaf attachment: alternate Leaf type: lobed Leaf type: simple

[photo of 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, becoming progressively smaller as they ascend the stem. Leaves near the flowers are typically small, narrow and unlobed. The main stem is ridged and roughly hairy. One plant has up to 15 stems, each heavily branched.

Notes:

I hate this plant—it is taking over everywhere at my favorite local park. The flowers of Spotted Knapweed have been mistaken for Wild Bergamot (Monarda fistulosa), which it vaguely resembles, but the leaves and overall plant structure are very different between the two species. The stems and bracts are stiff and scratchy, making walking through a patch of this an uncomfortable experience. Spotted Knapweed is on the prohibited/control weed list for Minnesota and should be eradicated. It contains chemicals that poison the soil and inhibit native plants. The hundreds of seeds produced by one plant mostly stay within a few feet of the parent plant, thus it tends to form large, monoculture colonies. The first year it sprouts there is just a rosette of leaves, with flowers appearing the second year. Spotted Knapweed is one of 3 targeted plant species in Minnesota with an active bio-control program. The other 2 species are leafy spurge and purple loosestrife. Spotted Knapweed also frequently goes by Latin names Centaurea biebersteinii and Centaurea maculosa.

Please visit our sponsors

  • Wild Ones Twin Cities Chapter

Where to buy native seed and plants ↓

Map of native plant purveyors in the upper midwest

  • Shop for native seeds and plants at PrairieMoon.com!
  • Shooting Star Native Seeds - Native Prairie Grass and Wildflower Seeds
  • Morning Sky Greenery - Native Prairie Plants
  • Minnesota Native Landscapes - Your Ecological Problem Solvers
  • Natural Shore Technologies - Using science to improve land and water

More photos

Photos taken at various places in Ramsey County.

Comments

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

Posted by: Jess - Duluth
on: 2009-06-22 17:47:30

Found this beautiful flower along the hiking/ski trail at Chester Bowl Park in Duluth MN. Flowering on June 22nd.

Posted by: K Chayka
on: 2009-06-22 18:58:05

Beauty is in the eye of the beholder, I think. :) I loathe this plant, myself. It is weedy and invasive and has started taking over the prairie at my favorite park. I look forward to the day when they get a bio agent in there to wipe it out.

Posted by: JB - Randall, Morrison County
on: 2010-07-09 15:49:41

Why is it suggested in the bio-control program to use gloves to hand pull this? Is it poisonous to touch? I pulled some to ID it today and now I'm worrying... We don't have too much, it's just starting to bloom and I plan to hand pull it.

Posted by: JB - Randall, Morrison County
on: 2010-07-09 15:54:16

Nevermind, they must recommend gloves because of the scratchy stems. :) Thanks!

Posted by: K. Chayka
on: 2010-07-09 20:14:51

JB, besides the scratchy stems, I think some people may have a reaction (rash?) to the chemicals in the plant.

Posted by: Anna - Brown County
on: 2010-07-20 10:50:19

We located a thriving population of Spotted Knapweed on 270th avenue in Brown County along the abandoned portion of the road that dips down into the creek valley. (map)

Beautiful Flower. Too bad it's so invasive.

Posted by: Tom - Grand Marais
on: 2010-08-05 23:44:02

I found this plant growing at the edge of our gravel driveway. I agree that the flowers are beautiful--too bad it's a noxious weed! I haven't noticed them before in this area, so I'm wondering where it came from.

Posted by: Rick - Eastern Cass Co. Remer, Longville, Outing
on: 2011-08-17 08:19:30

I believe I found Spotted Knapweed this morning but the leaves on my sample look somewhat different than in the website's photos, is there a similar plant blooming at this time. I'm pretty sure what I have is not a thistle.

Posted by: Rick - Eastern Cass Co. Remer, Longville, Outing
on: 2011-08-19 10:56:25

Upon further investigation I have concluded that it is Spotted Knapweed and I'm unfortunately starting to see more of it along the gravel road I walk along.

Posted by: Mark - Pine Springs Washington Co.
on: 2012-03-09 07:03:59

I have a lot of this in a field behind my house. Have been pulling it out for years.....

Posted by: Kara - Carleton County
on: 2012-07-08 16:06:04

Found this growing along the roadside in Carleton County today. There were just a few plants but sounds like next year there will be more

Posted by: Kathleen - Eagan, Minnesota
on: 2012-07-16 12:51:30

I found several plants blooming during my morning walk along the East side of Dodd Road between Esk Lane and Coventry Parkway in Eagan. It may be city property because it is along a walking/bike path. Is the city required to control invasive species?

Posted by: maia - Lebanon Hills Regional Park, Dakota County
on: 2012-08-18 22:21:25

Found this on the trails by Holland Lake. Apparently bees also mistake this for wild bergamot. Got a great macro photo of a bee on one of these blossoms.

Posted by: Judith - Lake Superior dunes
on: 2014-05-06 12:34:41

I'm in Michigan but want to mention an endangered and federally protected plant on Great Lakes dunes which looks very much like spotted knapweed. It is called Pitcher's Thistle. Please do not pull or poison this plant by mistake.

Posted by: K. Chayka
on: 2014-05-12 19:28:49

While Pitcher's thistle isn't present in Minnesota, it is in Wisconsin so our neighbors there should be aware of this look-alike plant.

Posted by: Kris - Fairview Township
on: 2014-08-07 22:38:32

There is a whole bunch of Spotted Knapweed growing by the side of the road (Cty Rd 77). A whole crop of Lead Plant and Spotted Knapweed. Purple flowers everywhere. Didn't notice that last year. Other purple flowers too.

Posted by: Mayra
on: 2015-07-16 15:36:12

there is a plant near my house that is very similar to knapweed, and it has a purple pink flower... what else is out there that are lookalikes

Posted by: K. Chayka
on: 2015-07-18 07:01:30

Mayra, you should read the Notes section above, that's just below the plant description info. Maybe Mondarda, maybe a thistle.

Posted by: Kimberly - Nobles County, southwest of Adrian
on: 2016-09-28 12:48:04

Infested pasture ~1 acre in size

Posted by: John J - Ponsford,MN
on: 2016-10-11 19:08:25

This plant is actively growing along Red Top Rd and ATV woodland trails on the west side of Bad Medicine Lake which is about 35miles NW of Park Rapids,MN. Thought it an attractive wild flower until I found it online - nasty.

Post a comment

Note: All comments are moderated before posting to keep the riff-raff out. An email address is required, but will not be posted—it will only be used for information exchange between the 2 of us (if needed) and will never be given to a 3rd party without your express permission.

For info on subjects other than plant identification (gardening, invasive species control, edible plants, etc.), please check the links and invasive species pages for additional resources.



(required)




Note: Comments or information about plants outside of Minnesota and neighboring states may not be posted because Id like to keep the focus of this web site centered on Minnesota. Thanks for your understanding.