St 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 is today most widely known as a herbal treatment for depression. According to the Cochrane Review, a key resource in evidence-based medicine, "the available evidence suggests that the hypericum extracts tested in the included trials are superior to placebo in patients with major depression; are similarly effective as standard antidepressants; and have fewer side effects than standard antidepressants.

Botanical description:St John's wort is a perennial plant with extensive, creeping rhizomes. Its stems are erect, branched in the upper section, and can grow to 1 m high. It has opposing, stalkless, narrow, oblong leaves which are 12 mm long or slightly larger. The leaves are yellow-green in color, with transparent dots throughout the tissue and occasionally with a few black dots on the lower surface. Its flowers measure up to 2.5 cm across, have five petals, and are colored bright yellow with conspicuous black dots. The flowers appear in broad cymes at the ends of the upper branches. The sepals are pointed, with glandular dots in the tissue. There are many stamens, which are united at the base into three bundles.