St. John's Wort
(Hypericum perforatum)

Hypericum perforatum, commonly known as St. John’s Wort, is a medicinal plant in the Plantae kingdom. It is in the subkingdom of Tracheobionta, and in the superdivision of Spermatophyta. St. John’s Wort is a flowering plant, which means it is in the Magnoliophyta division, in the Magnoliopsida class. Its subclass is Silleniidae, and it is in the Theales order. It is part of the Clusiaceae family, and its genus is Hypericum L.[1]

St. John's Wort
St. John's Wort
St. John's Wort, which is also called Klamath weed or goat weed, is a perennial.[5] It is used very frequently in herbal medicine all over the world. This herb comes in the form of teas, tablets, oil, and tincture that are made from the flowering tops of St. John's Wort.[3]

Clusiaceae Family
St. John’s Wort is a member of the Clusiaceae family, which consists of approximately 40 tropical trees and shrubs.[6] These plants typically have broad-ended, oblong, leathery leaves. The flowers of plants in the Clusiaceae family have several stamens joined in one grouping.[3]
Parts of St. John's Wort Flower
Parts of St. John's Wort Flower

St. John's Wort is a perennial; it typically lasts for about five years. H. perforatum grows from seeds, which should be planted outdoors directly after the last frost of the season.[1] These plants are able to grow with little to no attention, preferring to grow in full sunlight. St. John's Wort grow between 12 to 36 inches tall. The flowers bloom around mid summer, and consist of five yellow petals, 5 stamens, and clusters of stamens. [6]

Geographic Distribution
Distribution Map

Originally, St. John’s Wort was found growing wild in Europe and Asia. It then spread to the United States and Canada, where it grows in almost every state.[2] Although it can be very helpful when used medicinally, many farmers view St. John’s Wort as a weed.[1] St. John's Wort can be found in areas such as woods, dirt roads, and on the sides of streets and highways.[7]

Human Use
St. John's Wort Tea
St. John's Wort Tea
St. John’s W
St. John's Wort Tablets
St. John's Wort Tablets
ort has been used medicinally for hundreds of years by the ancient Romans and Greeks. As many as 2,400 years ago, H. perforatum was used to relieve arthritis, menstrual cramping, ulcers, and gastrointestinal problems.[3] Additionally, it was thought to have magic powers to ward off evil spirits.[7]

Several decades ago in Europe, doctors began to use St. John’s Wort for treatment in mild and moderate depression, which is a prevalent mental illness.[2] Recently, physicians throughout the United States have also been using it to treat individuals with mental and emotional disorders, such as depression, anxiety and relief from insomnia.[4]

St. John's Wort is successful at treating mild and/or moderate depression because it contains the compound hypericin. Hypericin is successful at providing emotional comfort when it reacts with certain brain chemicals.[5] With this newfound comfort, individuals may be relieved from depression.


Available over-the-counter in the United States, St. John's Wort can be taken by individuals experiencing mild to moderate depression. St. John's Wort pills are available in a variety of strengths, but the standardized dosage is 300 mg, with .3 hypericin concentration. Depending on the severity of the depression, these pills can be taken between two and 12 times per day.[5]

St. John's Wort is also available as a tea, by adding two teaspoons of the herb to boiling water. The effects of the pill and the tea are the same.[5]

Although St. John's Wort is a common treatment for many ailments, it has not been tested or approved by the FDA.[8] Therefore, the long-term effects of this herbal medicine are unknown.

Because H. perforatum is used medicinally, there are side effects just like any other medicine. Some of the common side effects are [9]:
  • Dry mouth
  • Dizziness
  • Diarrhea
  • Nausea
  • Sensitivity to the sun
  • Fatigue
  • Vivid dreams
  • Headaches
  • Restlessness
  • Mood changes
  • High blood pressure


In addition to the medicinal uses of St. John's Wort, there are also many traditions that the plant is used for. Some of the most popular traditions are [10]:
  • Believed to have magical powers to protect from evil
  • Burnt to banish evil & negativity
  • Hung in the home or carried to prevent spells of others from entering
  • Hung in the window on St. John's night to keep away ghosts
  • Picked and hung on the bedroom wall to give dreams of a future husband or wife
  • Hung around the neck to prevent fevers
    St. John the Baptist
    St. John the Baptist
  • Used in exorcisms
  • Worn to aid in war
  • Worn to help with problems of willpower and indecision

The binomial scientific name, Hypericum perforatum, means "over the apparition" in Greek. This refers to the old tradition that the plant would ward off evil spirits.[11] St. John's Wort, the common name, refers to St. John the Baptist. His birthday was June 24, which is right around the time that H. perforatum blooms.[5]

St. John's wort doth charm all the witches away.
If gathered at midnight on the saint's holy day.
And devils and witches have no power to harm
Those that do gather the plant for a charm:
Rub the lintels and post with that red juicy flower
No thunder nor tempest will then have the power
To hurt or to hinder your houses: and bind
Round your neck a charm of a similar kind.[7]
This poem discusses the magical powers that St. John's Wort was thought to have had.


[1] How to Grow St. John's Wort. The Gardener's Network. Web. 1 Dec. 2009. <>.
[2] Hypericum perforatum. Plants Database. Web. 1 Dec. 2009. <>.
[3] St. John's Wort & Depression. Web. 1 Dec. 2009. <>.

[4] St. John's Wort. National Center for Complementary and Alternative Medicine. Web. 1 Dec. 2009. <>.
[5] The Herb Called St. John's Wort. Health & Beyond. Web. <>.
[6] Clusiaceae Family - Hypericum. Flowers Gallery. Web. 1 Dec. 2009. <>.
Herbal Medicine: St. John's Wort Ancient Herbal Protector. Healthy. Web. 1 Dec. 2009. <>.
St. John's Wort Fast Facts. Dr. Donnica. Web. 1 Dec. 2009. <>.
St. John's Wort Side Effects. Med TV. Web. 1 Dec. 2009. <'s-wort/st.-john's-wort-side-effects.html>.
St. John's Wort (Hypericum perforatum). Global Herbal Supplies. Web. 1 Dec. 2009. <>.
St. John's Wort. Mother Nature. Web. 1 Dec. 2009. <>.