Centaurea cyanus L.

Bachelor's Button, Garden Cornflower, Bluebottle, Raggedy Sailors

Category
Forb/Herb

Description

Erect annual herb, 1.5 m tall, plant covered with loose white trichomes; outer ray florets are blue, 1.5-3 cm long, deeply toothed at apex.

Stem

Erect 0.2-1.2 m tall freely branching, pubescent, slender, angled in cross section, whitish in color.

Leaves

Alternate, 5-15 cm long, less than 1 cm wide, narrowly lance-shaped or linear, margins entire or slightly toothed, pubescent.

Flowers

Numerous solitary heads, 2.5-5 cm diameter, on long peduncle. Ray florets, blue, pink, purple, or white.

Fruit

Achene, 3-3.8 mm long, 1.5-2 mm wide, lustrous, purplish-gray in middle, yellowish basally.

Images

Photo: Rebekah D. Wallace, University of Georgia, Bugwood.org
More images of Centaurea cyanus

Life History

3. Habitat

Fields, pastures, roadsides, and waste sites.

Origin and Distribution

Native to Europe

Cornflower can be found in the following states/territories: USA (AL, AR, AZ, CA, CO, CT, DC, DE, FL, GA, HI, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VA, VT, WA, WI, WV, WY), CAN (AB, BC, MB, NB, NF, NS, ON, PE, QC, YT), DEN (GL)

Synonym

Leucacantha cyanus (L.) Nieuwl. & Lunell

h2. Management Recommendations

Mechanical Controls

Mechanical methods such as mowing, cutting, and digging will not eliminate hawkweed. Hand-pulling can be effective for small infestations if care is taken to remove as much of the root as possible. Mowing is ineffective because rosettes are so close to the ground. Effective hawkweed management will depend on a program that integrates control methods with restoration techniques to increase the competitive ability of desired species.

Herbicidal Controls

Cornflower can be controlled with herbicides. However, proper use of surfactants is necessary to increase the adherence of herbicides to the hairy leaves and stems. Plants should generally be treated when they are in the rosette stage. Effective control has been documented when using a mixture of glyphosate and aminopyralid or glyphosate and clopyralid at the chemical label’s recommended rate.

Biological Controls

There are no biological controls currently available.

Bibliography

Bryson, C.T. and M.S. DeFelice, eds. Weeds of the South. 2009. University of Georgia Press, Athens. 61 pp.

USDA, NRCS. 2010. The PLANTS Database, PLANTS Profile for Centaurea cyanus

http://msdssearch.dow.com/PublishedLiteratureDAS/dh08bb/0901b803808bb5d7.pdf?filepath=ivm/pdfs/noreg/010-50606.pdf&fromPage=GetDoc