Centaurea montana (Perennial Cornflower)

Plant Info
Also known as: Mountain Cornflower, Mountain Bluet, Bachelor's Button
Genus:Centaurea
Family:Asteraceae (Aster)
Life cycle:perennial
Origin:Europe
Status:
  • Weedy
Habitat:part shade, sun; disturbed soil; roadsides, fields, waste places, woodland edges, gardens
Bloom season:June - August
Plant height:10 to 30 inches
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 7+petals

[photo of flower] Showy flower heads 2 inches across, single or a few at the top of the stem. Each head consists of set of 10 to 20, blue to violet ray flowers around the outer edge and numerous, shorter purple disk flowers in the center. Ray flowers are sterile, widely spreading, narrowly tubular with 5 slender lobes as long as or longer than the tube. Disk flowers are fertile, erect to ascending, with a column of dark blue-violet tipped stamens and a divided style.

[photo of phyllaries] The bracts (phyllaries) surrounding the base of the flower are in several layers, appressed, triangular to egg-shaped, light green with blackish, finely toothed edging. The entire set of phyllaries (involucre) is ¾ to 1 inch long and longer than wide.

Leaves and stems: Leaf attachment: alternate Leaf type: simple

[photo of leaves] Leaves are alternate, green, lance-elliptic, 4 to 12 inches long, toothless or with a few small teeth, rarely lobed. The upper surface is sparsely short hairy, the lower more woolly hairy.

[photo of leaf extension down the stem] Leaves are stalkless but the leaf base extends down the stem, creating a wing. Stems are erect, single or multiple from the base, hairy and usually unbranched, sometimes few-branched. Colonies may be formed from creeping rhizomes or stolons.

Fruit: Fruit type: seed with plume

Seeds are elliptic, creamy colored to brown, smooth, 5 to 6 mm long with a tuft of short, light brown hairs at the tip.

Notes:

Perennial Cornflower is a European species popular in the garden trade, and occasionally escapes cultivation. It's certainly a pretty thing, and not likely to be confused with any other species except other garden variety Centaura species. Our chance encounter was in Grand Portage, on a roadside mixed with non-native Hawkweeds and other weeds. We feel this should be eradicated wherever encountered before it gets a chance to further proliferate in the wild. The north shore of Lake Superior is a hotbed for such things and the risk is high for a rhizomatous species that likes gravelly soil to settle in and further degrade this fragile habitat. Perennial Cornflower's native habitat is mountain meadows so is quite at home in cool, rocky places like the north shore. It can be quite vigorous and spreads by seeds as well as vegetatively—a double whammy. Let's not give this one a chance to make its mark.

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More photos

Photos by K. Chayka and Peter M. Dziuk taken in Cook County.

Comments

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

Posted by: Martha Decker - Grand Portage
on: 2018-08-01 04:13:54

Saw a lot of this in one spot along Old Hwy 61 in the Grand Portage area in July 2017. I haven't been back since to see if it's still there. Not knowing my flowers very well, I thought that it might be sage since this is on or very close to the Grand Portage Reservation. I was obviously wrong. I will look for it again when I'm in the area.

Posted by: Jeff Jackson - Bagley Nature Center, Duluth, MN
on: 2019-06-29 18:24:01

I found 2 isolated plants at Bagley Nature Center in Duluth. They were in full bloom in late June.

Posted by: Beverly - Lutsen
on: 2020-06-30 20:12:06

We just observed a patch in bloom along the bike trail between Lutsen and Tofte- of course mixed with hawkweed and the like. I was hoping to find that was native. Disappointing. Sometimes it seems like a lost cause on the North Shore. Hawkweed is on the summit of Eagle Mountain....

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