Sonchus asper (L.) Hill
Common Name: PRICKLY SOW-THISTLE
Coefficient of Conservatism: *
Coefficient of Wetness: 3
Wetness Index: FACU
Physiognomy: Ad A-Forb

Roadsides, railroads; a weed of cultivated fields and gardens; disturbed sites, including gravel pits, construction sites; disturbed deciduous forests, especially along trails and recent clearings; shores, marshy ground, river banks. Collected by the First Survey (1838) in Lenawee Co. and by 1888 collected in Keweenaw Co., so obviously long established in Michigan.

This species seems to set fruit well in this area, so the distinctive very compressed and smooth achenes are often available for positive identification. The large almost coiled auricles are often striking, especially as they, like the rest of the leaf margin, have prickles that tend to be longer, stiffer, and more numerous than in the other two species. Occasional plants with gland-tipped hairs as in S. arvensis var. arvensis may be called f. glandulosus Beckh.

Locations

Alger County
Alpena County
Benzie County
Berrien County
Calhoun County
Cass County
Charlevoix County
Cheboygan County
Chippewa County
    Including Drummond Island
Clinton County
Emmet County
Gogebic County
Grand Traverse County
Gratiot County
Hillsdale County
Houghton County
Ingham County
Iosco County
Isabella County
Jackson County
Kalamazoo County
Kent County
Keweenaw County
Lake County
Lapeer County
Leelanau County
Lenawee County
Luce County
Mackinac County
    Including Bois Blanc, Mackinac, Round Islands
Macomb County
Manistee County
Marquette County
Mecosta County
Midland County
Monroe County
Ontonagon County
Presque Isle County
Roscommon County
Schoolcraft County
St. Clair County
Van Buren County
Washtenaw County
Wayne County

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 15, 2017. http://www.michiganflora.net/species.aspx?id=474.