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St John's wort

St John's wort is the common name used for any member of the Hypericaceae family of annuals and perennials. St John's wort is also the common name of the species Hypericum perforatum, the best known member of that family. Hypericum perforatum is a yellow flowerering, rhizomatous, perennial herb indigenous to Europe, which has been introduced to the Americas and grows wild in many meadows. The name comes from the fact that it traditionally flowers by and is harvested on St John's day[?]; all above-ground parts are cut and dried for later use in the form of herbal tea, which has long been enjoyed both for its pleasant taste and for its medicinal properties.

In modern medicine, standardized Hypericum extract is commonly used as a treatment for depression and anxiety disorders. In homeopathy, Hypericum is also used in the treatment of asthma, blunt trauma[?], broken bones, gunshot wounds, hemorrhoids, spinal injury, and tetanus. Historically, the flowers and stems of St John's wort have also been used to produce red and yellow dye.

Although Hypericum perforatum is grown commercially in some regions, it is listed as a noxious weed in over twenty countries. Ingestion by livestock can cause photosensitization, central nervous system depression, spontaneous abortion, and can lead to death. Effective herbicides for control of Hypericum include 2,4-D, picloram, and glyphosate[?].

Medicinal properties

The first recorded use of Hypericum for medicinal purposes dates back to ancient Greece, and it has been used ever since. The herb was also used by Native Americans internally as an abortificant and externally as an anti-inflammatory, astringent, and antiseptic.

Hypericum Hidcote, a hybrid form used as a garden shrub.
Larger version

In some countries such as Germany, Hypericum is prescribed for mild depression, far more commonly than conventional antidepressant medication. Standardized extracts can be bought today as an over-the-counter remedy, usually in pill or capsule form. Many clinical studies have found it to be effective in the treatment of mild to moderate depression, with fewer side effects than many conventional antidepressant medications. Although it has not been found to be effective in the treatment of more serious forms of depression.

Although the exact mechanism by which it works is unclear, it is believed to involve slowing the disposal of serotonin, thus boosting serotonin levels.

The usual dosage is 900 mg of Hypericum extract per day, usually made up of three 300 mg capsules or tablets taken at different times of the day. Advocates recommend that, as with other antidepressants, Hypericum be taken for at least four weeks before judging its effectiveness.

In markets where standardized extracts are not available, the potency of samples can vary widely. Some brands of over-the-counter St. John's wort can be much more potent than others. The same can even be true of two dosage units from different batches of the same brand.

Major Hypericum varieties

Hypericum perforatum (also commonly known as Common St John's wort, Goat weed, or Klamath weed) is a rhizomatous perennial herb with ovate to linear leaves and deep yellow flowers. see photo (http://plants.usda.gov/cgi_bin/plant_profile.cgi?symbol=HYPE)). It is indigenous to Europe, West Asia, and North Africa.

Hypericum formosum (commonly known as Western St John's wort or Slender St John's wort) is an erect perennial with ovate to obovate leaves and deep yellow, black-dotted flowers. It is indigenous to western North America.

Hypericum anagalloides (commonly known as Bog St John's wort or Tinker's Penny) is a mat-forming annual with elliptic to obovate leaves and yellow to pinkish-orange flowers. It is indigenous to western North America.

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