Saint-John’s-Wort — St John’s wort used alone refers to the species Hypericum perforatum, also known as Tipton’s Weed or Klamath weed, but, with qualifiers, is used to refer to any species of the genus Hypericum. Therefore, H. perforatum is sometimes called Common St John’s wort to differentiate it. The species of Hypericum have been placed by some in the family Hypericaceae, but more recently have been included in the Clusiaceae. Approximately 370 species of the genus Hypericum exist worldwide with a native geographical distribution including temperate and subtropical regions of North America, Europe, Asia Minor, Russia, India and China.
St John’s wort can be visually recognized by leaf and flower type. Yellow, five petaled flowers approximately 20 mm across occur between late Spring and early to mid Summer. Leaves exhibit obvious translucent dots when held up to the light, giving them a ‘perforated’ appearance, hence the plant’s Latin name. When flowers or seed pods are crushed, a reddish/purple liquid is produced.
St John’s wort is today most widely known as a herbal treatment for depression. In some countries, such as Germany, it is commonly prescribed for mild depression, especially in children, adolescents, and where cost is a concern. Standardized extracts are generally available over the counter – however, in some countries (such as Ireland) a prescription is required. Extracts are usually in tablet or capsule form, and also in teabags and tinctures.