Claire continues with the medicinal plant diversity series:
Hypericum perforatum is known as common St. John’s wort — the name “St. John” stems from the traditional harvest time of Hypericum perforatum during the day of St. John on June 24th. The species belongs to a genus that includes a whopping 370 species worldwide. It has spread, via introduction, to temperate and subtropical regions in North America and Asia, with origins in Europe. Sadly, it is an invasive species or noxious weed in many countries, particularly because it is very toxic to livestock and can be lethal.
Contrasting to the effects it can have on animals, Hypericum perforatum‘s primary medicinal application is treatment for mild to intermediate forms of depression. It has also been used for less serious maladies like scrapes and cuts (early studies show some positive results for having antibacterial properties against gram-negative bacteria). The most medicinally-active chemicals in Hypericum perforatum are hypericin and hyperforin, which have proven to be effective in treating depression . These chemicals may function as inhibitors of monoamine oxidase, a compound associated with the illness. A study published in the Cochrane Database of Systematic Reviews suggests common St. John’s wort is more effective than a placebo and equivalent to tricyclin antidepressants for short-term treatment. St. John’s wort contains many other compounds (including oils, tannins, and flavinoids) that have been suggested as medicinal, though further research is needed.
Hypericum perforatum can be a lovely ornamental in gardens, drank as an herbal tea (though the taste, I was told, is a bit peculiar) and produces colours for dyes: a pleasant purple when the buds and fruits are crushed and yellow when the flowers are used. Needless to say, this is an intriguing and important species that could take some more looking into!