from the encyclopædic notes

ST JOHN’S WORT —   image of St John's wort from Wikipedia Commons

Hypericum perforatum. Now included among the Clusiaceae, formerly among the Hypericaceae. Infusions or tablets made from this plant are sometimes claimed today to be of use in case of depressive illness. In ancient times, it was used as a balm for wounds. Its modern name may derive from the traditional practice of gathering the flowers on 24 June, St John’s day.