Source: California Invasive Plant Council


URL of this page: http://www.cal-ipc.org/ip/management/plant_profiles/Hypericum_perforatum.php

Hypericum perforatum (St. John's wort, klamathweed)

Hypericum perforatum
Hypericum perforatum
Lake Tahoe Basin Weed Coordinating Group

Hypericum perforatum (common St. Johnswort, klamathweed) is an perennial plant (family Clusiaceae) grown for medicinal use, but it can be toxic to light colored livestock when consumed in large quantities. By 1940, more than 1 million hectares of California were infested by St. Johnswort, but biological control agents have eliminated most populations below 1500 m elevation.

Cal-IPC Inventory rating: Moderate

Cal-IPC Resources on Hypericum perforatum

Cal-IPC News Articles

  • Anonymous(1995). Biological control of invasive exotic pest plant species: A report on the importance of maintaining and enhancing our nation's biological control capabilities. CalEPPC News. 3: 6-10.
  • Connick, S. and M. Gerel (2005). Don't sell a pest: A new partnership to prevent plant invasions through horticulture. Cal-IPC News. 13: 4-5,14.
  • Donaldson, S. (2003). Fighting weeds in the Tahoe basin. CalEPPC News. 11: 7.
  • Hoekstra, B. (1997). Klamathweed. CalEPPC News. 5: 9.
  • Pitcairn, M. (2000). All weeds that have approved biological control agents, accidental introductions and others. CalEPPC News. 8.

Cal-IPC Symposium Proceedings

  • Connick, S. and M. Gerel (2004). Partnering to prevent invasions of plants of horticultural origin. California Invasive Plant Council Symposium 2004. Ventura, CA.
  • Donaldson, S., W. West, et al. (2003). Getting the job done: Working within the regulatory environment at Lake Tahoe to manage weeds. California Invasive Plant Council Symposium 2003. Kings Beach, CA.
  • Kirk, A. A., T. Widmer, et al. (2003). The potential contribution of natural enemies from Mediterranean Europe to the management of the invasive weed Arundo donax (Graminae; Arundinae) in the U.S. California Invasive Plant Council Symposium 2003. Kings Beach, CA.
  • Pitcairn, M. J. and D. M. Woods (1998). Control methods: Biological control. California Exotic Pest Plant Council Symposium '98. Ontario, CA.
  • Pitcairn, M. J. and D. M. Woods (1998). Control methods: biological control. California Exotic Pest Plant Council Symposium 1998. Ontario, CA.
  • Thomsen, C. D., W. A. Williams, et al. (1996). Yellow starthistle management with grazing, mowing, and competitive plantings. California Exotic Pest Plant Council Symposium '96. San Diego, CA.

Other Resources on Hypericum perforatum