St. John’s Wort (Hypericum perforatum)

St. John’s Wort (Hypericum perforatum) is a useful herbal medicine and is listed in South Africa as an invasive, noxious weed – this makes it the perfect plant ally to seek out to enjoy its benefits without impacting our country’s biodiversity. This non-aromatic herb is found across a few provinces and is fairly widespread, although indigenous Hypericum species are far more prevalent. They do not contain the same medicinal value as H. perforatum but are showy plants bearing bright yellow flowers.

St. John’s Wort (Hypericum performatum). © Justin Williams

An easy way to identify St. John’s Wort is by first looking for the tiny glandular dots on the leaf, and then secondly crushing the leaf between your fingers to reveal a reddish colouration in the crushed leaf matter – this red colouration is derived from some of its medicinal compounds. The flowering tops, leaves and stems are gathered while the flowers are blooming at the height of summer. This is generally around the summer solstice, and it bears the other name of Solsticewort for this reason. The feast of St. John the Baptist coincides with midsummer in the northern hemisphere, a time when dried bunches of this herb were hung on house doors to ward off evil spirits. In South Africa, our introduced “weed” flowers from November to January.

St. John’s Wort is most commonly prescribed to treat depression and mood disorders. While healing always differs from person to person, strong scientific evidence attributes therapeutic value to hypericin and hyperforin, two native compounds that act on the messengers in our nervous system, uplifting our mood. There are precautions to bear in mind, as St. John’s Wort does not interact well with other medications like other antidepressants and antibiotics and serious interactions may occur. For this reason the medicine is regulated in many countries and available with a prescription from a qualified medical practitioner.