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You are here: Home / Plants / Species Profiles / St. Johnswort
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Species Profiles

St. Johnswort

St. JohnswortScientific name: Hypericum perforatum L.

Common names: St. Johnswort, St. John's wort, common St. Johnswort, Klamath weed, common goatweed, tipton weed

Click image to enlarge

Native To: Eurasia and North Africa (Zouhar 2004)

Date of U.S. Introduction: 1700s (Zouhar 2004)

Images: Invasive.org and Google

Means of Introduction: Introduced as an ornamental and as a medicinal herb (Klein 2011)

Impact: Crowds out native species and forage on pasturelands; toxic to livestock (Klein 2011; Zouhar 2004)

Current U.S. Distribution:

U.S. States and U.S. National Parks Where Reported Invasive: Invasive Plant Atlas of the United States map

Management Plans: Plants

Selected Internet Resources:

Federal Government

Hypericum perforatum
Integrated Taxonomic Information System.
Taxonomy

Hypericum perforatum L. (Klamath Weed) - Noxious and Nuisance Plant Management Information System (PMIS)
DOD. USACE. Engineer Research and Development Center. Environmental Laboratory.
Identification/Description; Photographs; Introduction History; Impacts; Distribution; Controls

Hypericum perforatum Article Citation Search - AGRICOLA Database
USDA. National Agricultural Library.
Research; Special Note: NAL Catalog Search (resources)

Hypericum perforatum L. - Germplasm Resources Information Network (GRIN)
USDA. ARS. National Genetic Resources Program.
Taxonomy

St. Johnswort
USDA. ARS. Poisonous Plant Research Laboratory.
Identification/Description; Photographs; Impacts; Habitat; Distribution; Controls

Common St. John's Wort - Weed of the Week (Jan 8, 2007; PDF | 80 KB)
USDA. FS. Northeastern Area. Forest Health Protection.
Identification/Description; Photographs; Introduction History; Impacts; Habitat; Distribution; Controls

Wanted: Dead - St. Johnswort
USDA. FS. Pacific Northwest Research Station. Blue Mountains Natural Resources Institute.
Identification/Description; Photographs; Impacts; Controls

Hypericum perforatum - Fire Effects Information System (FEIS)
USDA. FS. Rocky Mountain Research Station. Fire Sciences Laboratory.
Taxonomy; Identification/Description; Introduction History; Impacts; Life Cycle; Habitat; Distribution; Controls; Special Note: References

Ecology and Management of Common St. Johnswort - Invasive Species Technical Note MT-14 (Jul 2007; PDF | 492KB)
USDA. Natural Resources Conservation Service.
Identification/Description; Introduction History; Impacts; Habitat; Distribution; Controls

Plant Profile for Hypericum perforatum - PLANTS Database
USDA. NRCS. National Plant Data Center.
Taxonomy; Photographs; Distribution; Legal Aspects

Hypericum perforatum L. - An Assessment of Exotic Plant Species of Rocky Mountain National Park
DOI. Northern Prairie Wildlife Research Center.
Impacts; Life Cycle; Distribution; Controls

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State Government

Klamath Weed
California Bureau of Land Management. Arcata Field Office.
Identification/Description; Photographs; Impacts; Habitat; Distribution

Common St. Johnswort or Klamathweed - EncycloWeedia
California Department of Food and Agriculture.
Identification/Description; Photographs; Introduction History; Impacts; Habitat; Life Cycle; Distribution; Dispersion; Controls

Common St. Johnswort
Colorado Department of Agriculture. Noxious Weed Management Program.
Identification/Description; Photographs; Introduction History; Impacts; Distribution; Controls

Weeds: St. Johnswort (PDF | 120 KB)
Oregon Department of Agriculture. Plant Division.
Identification/Description; Photographs; Introduction History; Impacts; Habitat; Distribution; Controls; Legal Aspects

Class C Noxious Weed: Common St. Johnswort
Washington State Noxious Weed Control Board.
Taxonomy; Identification/Description; Photographs; Impacts; Habitat; Distribution; Dispersion; Controls; Legal Aspects

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University/Academic

Common St. Johnswort - Invasive Plant Species of Alaska (PDF | 128 KB)
University of Alaska - Anchorage. Alaska Natural Heritage Program.
Identification/Description; Photographs; Impacts; Life Cycle; Distribution; Dispersion; Controls

Common St. Johnswort - Invasive Plant Atlas of the United States
University of Georgia. Center for Invasive Species and Ecosystem Health.
Taxonomy; Identification/Description; Photographs; Introduction History; Distribution

Common St. Johnswort, Klamath Weed - Indiana Plants Poisonous to Livestock and Pets
Purdue University. Cooperative Extension Service.
Identification/Description; Photographs; Illustrations; Impacts; Habitat; Controls

St. Johnswort: Identification, Management and Control
University of Nebraska - Lincoln. Cooperative Extension.
Identification/Description; Photographs; Impacts; Controls

Klamath Weed Wanted Poster--Dead, Not Alive! (PDF | 37 KB)
University of Nevada - Reno. Cooperative Extension.
Identification/Description; Photographs

Managing Common St. Johnswort (PDF | 332 KB)
University of Nevada - Reno. Cooperative Extension.
Identification/Description; Photographs; Impacts; Habitat; Controls

Common St. Johnswort - Ohio Perennial & Biennial Weed Guide
Ohio State University. Ohio Agricultural Research and Development Center.
Identification/Description; Photographs; Habitat; Distribution

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International

St. John's-wort - Guide to Weeds in British Columbia
British Columbia Ministry of Agriculture, Food, and Fisheries (Canada).
Identification/Description; Photographs; Impacts; Distribution

St. John's wort - Best Practice Management Guide for Environmental Weeds (PDF | 607 KB)
Cooperative Research Centre for Australian Weed Management.
Identification/Description; Photographs; Introduction History; Impacts; Habitat; Distribution; Dispersion; Controls; Legal Aspects

Weed Profile: St John's wort
New South Wales Department of Primary Industries (Australia).
Identification/Description; Photographs; Impacts; Distribution; Dispersion; Controls; Legal Aspects

Hypericum perforatum (herb) - ISSG Global Invasive Species Database
World Conservation Union. Invasive Species Specialist Group.
Taxonomy; Identification/Description; Photographs; Impacts; Life Cycle; Habitat; Distribution; Controls

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Organizations

Hypericum perforatum
Pacific Island Ecosystems at Risk.
Identification/Description; Photographs; Habitat; Distribution; Dispersion

St. Johnswort
Montana War on Weeds.
Identification/Description; Photographs; Impacts; Life Cycle; Controls

St. Johnswort
Montana Weed Control Association.
Identification/Description; Photographs; Habitat; Distribution

Citations

Klein, H. 2011. Common St. Johnswort (PDF | 128 KB) University of Alaska Anchorage. Alaska Exotic Plants Information Clearinghouse.

Zouhar, K. 2004. Hypericum perforatum. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

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Last Modified: Dec 15, 2013
 
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