Hypericum is a genus of about 400 species of flowering plants in the family Hypericaceae.The genus has a nearly worldwide distribution, missing only from tropical lowlands, deserts and polar regions. All members of the genus may be referred to as St. John's wort, though they are also commonly just called hypericum, and some are known as tutsan.
Two main compounds of interest have been studied in more detail: hyperforin and hypericin. However, the pharmacology of H. perforatum is not resolved, and at least its antidepressant properties are caused by a wide range of factors interacting. As psychiatric medication, it is usually taken as pills, or as tea. Few standardised preparations are available, and research has mainly studied alcoholic extracts and isolated compounds.
Hypericum is a common treatment in homeopathy, used for the healing of deep wounds or as a relief from depression.