Hypericum perforatum L.
Common Name: KLAMATH WEED, GOATWEED, COMMON ST. JOHN'S-WORT
Coefficient of Conservatism: *
Coefficient of Wetness: 5
Wetness Index: UPL
Physiognomy: Ad P-Forb

Abundant on fields, roadsides, and railroads; spreading to rock outcrops, shores, and elsewhere. A thoroughly naturalized weed, originally from Europe. First collected in Michigan in 1839 by D. Cooley in Macomb Co.

Although other species of Hypericum are also poisonous if ingested, this abundant species has been an important livestock-poisoning plant, especially in western North America. One of its properties is to make animals hypersensitive to light.

This species is much less black-spotted than H. punctatum, but it does have prominent translucent dots in the leaves. The stem is angled (compared to terete in H. punctatum); a ridge extends downward from the base of the midrib of each leaf.

Locations

Alcona County
Alger County
Allegan County
Alpena County
Antrim County
Arenac County
Baraga County
Barry County
Benzie County
Berrien County
Branch County
Calhoun County
Cass 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
Hillsdale County
Houghton County
Huron County
Ingham County
Ionia 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
Missaukee County
Monroe County
Montcalm County
Montmorency County
Muskegon County
Newaygo County
Oakland County
Oceana County
Ogemaw County
Ontonagon County
Oscoda County
Otsego County
Ottawa County
Presque Isle County
Roscommon County
Saginaw County
Sanilac County
Schoolcraft County
Shiawassee 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 11, 2017. http://www.michiganflora.net/species.aspx?id=1465.