COMMON ST. JOHN'S-WORT (HYPERICUM PERFORATUM)
St.-John’s-wort (Hypericum) includes both native plants and introduced weeds, the commonest of which is the European Hypericum perforatum. This rangy opportunist has invaded roadsides, pastures, and cutover forest all across Nova Scotia.
The golden-yellow flowers bloom profusely in midsummer. If you pick the opposite leaves and hold them up to the sunlight, you can see they are marked with many little, translucent dots, which can be the source of serious skin irritations.
In Teutonic mythology, the plants were associated with the sun god, Baldur, whose festival was held annually around June 24, when the sun is in the sky longer than at any other time of the year.
With the ascendancy of Christianity, Baldur lost out, and his date was assigned to the feast day of St. John the Baptist. So, Baldur’s sunny yellow flowers became dedicated to the “voice crying in the wilderness.”
The herbal term wort has medical significance. It is a corruption of the Old English wyrt, which is Anglo-Saxon for “useful pot-herb.” In ancient medicine, St.-John’s-wort was renowned as a vulnerary—a remedy for the healing of wounds—as well as for internal applications.
Currently, it is used in psychiatry and herbal medicine in the treatment of various depression disorders (hyperforin). Care must be taken in using products containing hypericin; once light sensitivity is induced, it cannot be easily reversed.
Livestock grazing pastures infested with this plant and their agricultural attendants run a high risk of repeated exposure.
Other, native species of Hypericum contain various amounts of hypericin, but the introduced weed is the most problematic.
Leaves and stems contain the latex.
The sap (sticky latex) contains several glycosides, the quantity and efficacy depending upon the species.
TYPICAL POISONING SCENARIO
Consumption of leaves and stems, by children or those seeking a herbal cure.
The glycosides are generally cathartic (purgative, laxative).
COMMON ST. JOHN'S-WORT POISON INFORMATION
Phototoxins are chemical substances that make the skin very sensitive to the ultraviolet radiation in sunlight and other light sources.