Centaurea stoebe L.
Common Name: SPOTTED KNAPWEED
Synonym: Centaurea maculosa
Coefficient of Conservatism: *
Coefficient of Wetness: 5
Wetness Index: UPL
Physiognomy: Ad B-Forb

C. maculosa of Michigan Flora.

A Eurasian invader first collected in 1911 in an alfalfa field at Hesperia (on the Oceana/Newaygo Co. line); no collector is recorded. Now spread aggressively everywhere: old fields on poor soil, roadsides, disturbed sites, and disturbed places, especially in the northern part of the state, where it takes over open sites.

Our plants are subsp. micranthos (Gugler) Hayek, sometimes called C. biebersteinii DC. Since the introduction of C. diffusa, these two species seem to have hybridized extensively in some areas, blurring the distinctions in the key.

Locations

Alcona County
Alger County
Allegan County
Alpena County
Antrim County
Arenac County
    Including Charity Island
Baraga County
Barry County
Benzie County
Berrien County
Branch County
Calhoun County
Charlevoix County
    Including Beaver Island
Cheboygan County
Chippewa County
    Including Drummond Island
Clare County
Clinton County
Crawford County
Delta County
Dickinson County
Emmet County
Genesee County
Gladwin County
Gogebic County
Grand Traverse County
Gratiot County
Hillsdale County
Houghton County
Huron County
Ingham County
Iosco County
Iron County
Isabella County
Jackson County
Kalamazoo County
Kalkaska County
Kent County
Keweenaw County
    Including Isle Royale
Lake County
Lapeer County
Leelanau County
    Including Fox Islands
    Including Manitou Islands
Lenawee County
Livingston County
Luce County
Mackinac County
    Including Bois Blanc, Mackinac, Round Islands
Macomb County
Manistee County
Marquette County
Mason County
Mecosta County
Menominee County
Midland County
Monroe County
Montcalm County
Montmorency County
Muskegon County
Newaygo County
Oakland County
Oceana County
Ogemaw County
Ontonagon County
Osceola County
Oscoda County
Otsego County
Ottawa County
Presque Isle County
Roscommon County
Saginaw County
Schoolcraft County
St. Clair County
St. Joseph County
Tuscola County
Van Buren County
Washtenaw County
Wayne County
Wexford County

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 18, 2017. http://michiganflora.net/species.aspx?id=277.